3. As far as practical, the body part being radiographed should be perpendicular to the main x-ray beam (called central ray or CR) and parallel to the film (paralleling technique).

4. Use proper immobilization methods to insure that the patient does not move during exposure. Film holding instruments should be used instead of the patient retaining the film with his or her finger.

5. Use an exposure time that is as short as possible to minimize patient motion during exposure.

6. Ensure that the focal spot-to-film distance (FFD) is correct (preferably at least 16 inches).

7. All patient exposures recorded in the patient's chart, radiographs should be properly labled, and diagnostic information obtained from the radiographs recorded in the patient's chart.

D. Using proper kilovolt peak (kVp) technique

Kilovoltage determines the penetrating ability (quality and to a great extent also quantity) of the x-ray beam. When a high kVp is used, the contrast of the resultant radiograph will be less (more shades of gray) than when low kVp is used. Most of the newer dental x-ray units have fixed milliamperage (mA) and fixed kilovoltage (kVp). Thus, in such instances the variable factors are: exposure time, target-to-film distance and the speed of the film.

E. Milliamperage (mA) and time setting

Milliampere-seconds (mAs) determines the amount (quantity) of x-radiation and is calculated by multiplying the milliamperage (mA) x time (in seconds) = mAs (milliampere-seconds).

A common practice is to set the mA at the highest setting available on the particular dental x-ray machine and then establish the proper timer settings. This technique results in the use of shorter time settings, which are helpful in avoiding patient motion artifacts on the radiograph.

F. Protecting yourself from unnecessary radiation exposure

1. During the exposure dental personnel who perform dental radiography should stand behind a protective barrier [30311 (b) (2)]. In those cases where the dental personnel cannot stand behind a protective barrier, they must stand at least 6 feet away from the patient and the x-ray tube, not in the path of the primary beam [30311 (b) (2)] but preferably behind a fixed or mobile barrier such as a wall or movable leaded Plexiglas shield.

2. Increase the distance between the patient (the source of scattered radiation) and the x-ray operator to over 6 feet. The intensity of the primary x-ray beam, scatter radiation and leakage from the x-ray tube diminishes rapidly as the distance between the dental x-ray operator and the source of radiation (patient) increases (approximately by the square of the distance). If a dental x-ray operator can increase his or her distance from radiation source by a factor of 2, his or her exposure would be reduced to 1/4 of the original amount.

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SECTION V - DENTAL RADIOGRAPHIC QUALITY ASSURANCE (QA) AND QUALITY CONTROL (QC)

Quality assurance (QA) program should include x-ray and ancillary equipment, education of dental personnel to perform quality control (QC), and preventive maintenance procedures. To complete the daily QC at the beginning of the work day does not take more than five to ten minutes of dental personnel time.

The primary cost saving of a QA program results from a decrease in repeat studies. The cost savings include reduction in:

• Downtime of equipment
• Dental personnel time
• Cost of equipment service

Quality assurance (QA) equipment needed includes:

• Thermometer (dial, digital or electronic but not alcohol or mercury because these may break and contaminate processing solutions).
• Step wedge (or a sensitometer and densitometer). An aluminum step wedge, acquired from an x-ray accessories supplier or provided by a service representative.

A typical protocol for using a step wedge for checking processing solutions is as follows:

1. Expose 15 to 20 films with a step wedge using identical exposure factors (same time, kVp and mA for a molar projection) and focal film distance.

2. Process one film in a recently cleaned processor with fresh chemicals. This film will be used as a standard for comparison.

3. Place the remaining films in a cool, dry place, protected from any radiation sources.

4. Process one of these remaining exposed test films daily and compare with the standard film.

5. If differences are noted between the test film and standard film, these can be attributed to faulty processing conditions (usually exhausted chemistry), film fog, or inconsistent exposure.

6. Each time solutions are changed, evaluation of the developing system should be done.

The standard film can also be used on a monthly basis as a comparison to detect changes in the exposure factors of your x-ray unit, if changes in density or contrast are noted.

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SECTION VI - EQUIPMENT QA REQUIREMENTS (General Provisions)

All equipment used for producing quality, diagnostic radiographs should be checked periodically to insure optimum performance. Due to the sensitive nature of the tests and the cost of the testing equipment, a qualified service representative for the type of dental x-ray unit needing evaluation should be contacted to perform the necessary tests. Periodic testing should include x-ray output, half value layer, mA and kVp calibration, timer accuracy, and collimation and beam alignment.

Tube head stability should be checked at least monthly. Extend the arm of the x-ray unit fully, release the unit and observe for drift or vibration. Move the head to multiple locations and angulations and repeat the procedure. If any drift is noted, adjust the unit according to the manufacturer's instructions or have the service performed by a qualified technician.

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SECTION VII - DARKROOM QA REQUIREMENTS (General Provisions)

A. Establish a consistent routine in the darkroom.

B. No smoking, eating, or drinking is permitted in the darkroom.

C. The darkroom should be kept free of dust.

D. Counter tops and processor feed trays shall be cleaned daily.

E. Hands should gloved appropriately when working with film packets contaminated with blood or saliva. Please refer to your office infection control protocol for proper techniques to be followed in the individual office. Hands should be clean, dry and free of glove powder when handling dental films.

F. The darkroom safelight shall be equipped with a combination of an appropriate bulb and a safelight filter (15 watt bulb with a GBX 2 filter).

G. Films should be handled carefully to prevent artifacts due to static electricity or fingerprints.

H. When hand processing is used, stir solutions well in the morning before use. Be sure to use separate stirring paddles for the developer and the fixer to prevent cross-contamination.

I. Cover both the developer and the fixer tanks when not in use to prevent oxidation of the processing solutions.

J. Practice good housekeeping by wiping up spilled solutions immediately, washing hangers after each use, and always using clean, dry hangers.

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SECTION VIII - FILM PROCESSING QUALITY ASSURANCE

A. Film and chemical storage

Photographic material (dental film) should be stored at temperatures less than 24C (75F), preferably in the range of 15 to 21C (60 to 70F). Open packages of dental film should be stored on edge (never flat) in an area with humidity ranging between 40 to 60 percent and in areas where they cannot be exposed to chemical fumes or radiation. If the humidity is allowed to drop below 40 percent, an increase in static marks on the film may result. If humidity rises above 60 percent, the films sometimes will become sticky and film handling becomes difficult. Processing chemicals should also be stored in an upright position. Chemicals should never be allowed to freeze.

B. Darkroom conditions

The darkroom should be properly illuminated, that is, the safelight should be correctly matched with the film in order to avoid film fogging.

Safelight

A proper safelight provides ample lighting during processing, yet is safe for sensitive films. An improper safelight will fog the films. Recommendations:

• Use 15 watt bulb with a GBX 2 filter.
• Place safelight at least 4 feet from working surface.
• Check for cracked or faded filter at least annually.
• Keep safelight exposure of unprocessed films as short as practical.

Procedure for checking safelight safety:

• Place film on work surface below the safelight.
• Place a small coin on the film.
• Turn on the safelight.
• Leave film exposed to safelight for the length of time it requires to unwrap and clip a full-mouth series, about five minutes.
• Process the film.
• Presence of coin outline indicates a defective safelight.
• Correct any deficiency by replacing either the bulb or the safelight filter, or increasing the distance between the safelight and working surface.

Checking for darkroom fog

Adequate time (15 to 20 minutes) should be spent in the darkroom before testing for darkroom fog to allow for dark adaptation and to allow visual inspection of the darkroom for light leaks. Light leaks cause fogging of films with substantial loss in film detail and contrast.

Light leaks can be detected as follows:

• Close and lock door.
• Turn off all lights.
• Dark adapt eyes for 15 to 20 minutes.
• Look for light leaks.
• Mark light leaks with chalk.

Light leaks can be eliminated as follows:

• Processing in old, exhausted solutions.
• Processing in poorly mixed solutions.
• Using outdated film.
• Storing unexposed film at high temperature.
• Storing unexposed film in contact with chemical fumes or radiation exposure.
• Failing to store films in a protective container.

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SECTION IX - MANUAL FILM PROCESSING

Proper processing of films is very important in optimizing diagnostic quality dental radiographs and in reducing the number of retakes. An x-ray film should never be overexposed in order to shorten the developing time.

A film that has been overexposed and underdeveloped tends to lose much of its diagnostic quality and results in a significant increase in exposure to patient and possibly to dental personnel.

Developing for five (5) minutes at 68F - 70F produces optimum diagnostic quality films. Since the correct developing time varies with the temperature of the developing solution, measurements must be made with an accurate thermometer and timer.

Full Film Processing Techniques
Developer: Temperature (Fahrenheit)	Minimum time (minutes)
64 - 66	7
68 - 70 (optimum)	5
72 - 76	4

A thermometer must be kept in the developing solution. Temperature should be checked and developing time adjusted in accordance with the temperature each time film is developed.

The temperature of developing solutions should not exceed 75F or fall below 65F. Developing solutions function correctly only within the above noted temperature range.

In addition, dental personnel must follow these rules:

• Use solutions designed for use with dental x-ray film.
• Change solutions regularly per manufacturer's recommendations.
• Replenish solutions properly per manufacturer's recommendations.
• Avoid contaminating solutions (be sure to have separate stirring paddles for developer and fixer solutions).
• Keep films in the fixer solution for at least 10 minutes.
• Wash films in a running water bath for at least 20 minutes.
• Dry films thoroughly in a dust-free environment.

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SECTION X - AUTOMATIC FILM PROCESSING

When chemicals are formulated for automatic film processing, the manufacturers assume that a certain number of films of various sizes and of typical radiographic density will be processed daily. Most automatic processors require processing of at least 25-50 films daily. Please refer to the manufacturer's recommendations for your particular processor to determine if any adjustments may need to be made in the type of chemistry or replenishment rates.

The processor QC program should monitor the following:

1. Processor Sensitometric (Step Wedge) Evaluation

Processor QC should be carried out at the beginning of each day, after sufficient time has elapsed for the developer temperature to reach its operating level and all systems have stabilized. A sample protocol for using a step wedge is listed in Section V.

2. Tank Level Check, Clean-up Films, Cleaning of Crossover Rollers

At the end of the work day the cross-over rollers should be removed, cleaned with warm water and a damp, soft cloth, and dried. The cover of the processor should be left open about 5 cm (2 inches).

3. Fixer Replenishment Rate

Fixer solutions should be changed regularly, usually when developer solutions are changed. Fixer tanks and racks should be cleaned at that time. The pH or silver concentration may be monitored as an indicator of fixer activity. It should be noted that it is impossible to overreplenish fixer; however, in order to optimize the cost, the amount of fixer replenished or added should be as specified by the manufacturer.

4. Fixer Flow Meter Accuracy

Check fixer replenishment rates daily using the built-in flow meter, if so equipped; otherwise use a graduated cylinder and compare to the manufacturer's recommendations. The accuracy of the flow meter should be checked semiannually.

5. Washing Time

A useful tool in ensuring adequate film washing is a flow meter on the water line feeding the processor. The flow meter should be visually inspected daily to ensure adequate water flow. An in-line water filter may be necessary if water supply contains particulate matter.

6. Film Fixer Retention

Too much fixer retained on the film will discolor the film over time leading to image degradation. Films should be adequately washed and finished radiographs should be stored at 21C (70F) and 40 - 60% humidity. There are tests for fixer retention in processed films. Most kits require that a few drops of the test solution be applied to one emulsion so that the resulting stain be compared with a standard sample. For archival purposes, less then 2g/cm thiosulfate ion (fixer) should remain in the film after washing.

7. Processor Transport Time

Automatic processors have more or less fixed transport speeds or times. These speeds or times can be changed internally if necessary. Even small changes in transport time can significantly affect the development time. The total developer immersion time is only 20 seconds for a 90-second processor.

The processor transport time is measured, using a stop watch, from the instant the leading edge of the film enters the entrance roller until the leading edge exits the last set of rollers in the drier section of the processor.

8. Developer Temperature

The developer temperature should be maintained as recommended by the manufacturer for the specific film-developer combination being used and should not vary more than 0.3C ( 0.5F).

9. Wash Water Temperature

An in-line thermometer should be used to monitor the wash-water temperature.

10. Built-in Developer Thermometer Accuracy

The accuracy of the thermometer should be checked at least monthly against another thermometer.

11. Developer Recirculation Filter

Every processor should also contain a filter in the developer recirculating system. This filter should be changed regularly as recommended by the manufacturer.

12. Replenishment Rate

The replenishment rates should be those suggested by the film manufacturer as required by workload.

13. Water Flow Meter Accuracy

A water-flow meter should be provided at the point where the water enters the processor. The replenishment flow meter should be calibrated when the processor is installed and the calibration should be checked quarterly.

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SECTION XI - GUIDELINES FOR PRESCRIBING DENTAL RADIOGRAPHS

The use of patient selection criteria insures that each patient exposure will have maximum diagnostic benefit. Patient selection criteria are descriptions of clinical conditions derived from patient signs, symptoms and history that identify patients who are likely to benefit from a particular radiographic examination. The guidelines are designed to ensure continuous radiographic surveillance for caries, alveolar bone loss associated with periodontal disease, periapical disease and other latent pathology. These guidelines were developed by a panel of general dentists and specialists sponsored by the FDA and were the result of a review of the many studies available on the incidence and progression rates of caries, periodontal disease, growth and development assessment and latent pathology.

The guidelines categorize patients first by type of visit (new or recall), then by dental status (child with primary or transitional dentition, adolescent, or adult dentulous or edentulous). Lastly the patient's risk category for caries, periodontal disease or growth and development assessment is considered.

Use of these guidelines should promote the appropiate use of x-rays, to reduce overutilization and excessive radiation, and underutilization with potential inadequate diagnosis.

GUIDELINES FOR PRESCRIBING DENTAL RADIOGRAPHS

PATIENT CATEGORY	CHILD
	Primary Dentition (prior to eruption of first permanent tooth)	Transition Dentition (following eruption of first permanent tooth)
NEW PATIENT*
All new patients to assess dental diseases and growth and development	Posterior bitewing examination is proximal surfaces of primary teeth cannot be visualized or probed.	Individualized radiographic examination consisting of periapical/occlusal views and posterior bitewing or panoramic examinations and posterior bitewings
RECALL PATIENTS*	Posterior bitewing examination at 6-month intervals or until no carious lesions are evident
No clinical disease and no high risk factors or caries**	Posterior bitewing examination at 12-month intervals if proximal surfaces or primary teeth cannot be visualized or probed	Posterior bitewing examination at 12-24 month intervals
Periodontal disease or history of periodontal treatment	Individualized radiographic examination consisting of selected periapical and/or bitewing radiographs for areas where peridental disease (other than nonspecific gingivitis) can be demonstrated clinically
Growth and development assessment	Usually not indicated	Individualized radiographic examination consisting of a periapical/occlusal or panoramic examination

*Clinical situations for which radiographs may be indicated include:

A. Positive Historical Findings

1. Previous periodontal or endodontic therapy

2. History of pain or trauma. Presence of implants

3. Family history of dental anomalies

4. Postoperative evaluation of healing

5. Presence of implants

B. Positive Clinical Signs/Symptoms

1. Clinical presence of periodontal disease

2 Large or deep restorations

3. Deep carious lesions

4. Malposed or clinically impacted teeth

5. Swelling

6. Evidence of facial trauma

7. Mobility of teeth

8. Fistula or sinus tract infection

9. Clinically suspected sinus pathology

10. Growth abnormalities

11. Oral involvement in known or suspected systemic disease

12. Positive neurological findings in the head and neck

13. Evidence of foreign objects

14. Pain and/or dysfunction of the temporomandibular joint

15. Facial asymmetry

16. Abutment teeth for fixed or removable partial prosthesis

17. Unexplained bleeding

18. Unexplained sensitivity of teeth

19. Unusual toot morphology, calcification or color

20. Missing teeth with unknown reason

PATIENT CATEGORY	ADOLESCENT	ADULT
	Permanent Dentition (prior to eruption of third molars)	Dentulous	Edentulous
NEW PATIENT*
All new patients to assess dental diseases and growth and development	Individualized radiographic examination consisting of posterior bitewing and selected periapicals. A full mouth intraoral radiographic examination is appropriate when the patient presents with clinical evidence of generalized dental disease or a history of extensive dental treatment		Full mouth intraoral radiographic examination or panoramic examination
RECALL PATIENTS*
Clinical caries or high-risk factors for caries**	Posterior bitewing examination at 6-12 month intervals or until no caries lesions are evident	Posterior bitewing examination at 12-18 month intervals	Not applicable
No clinical disease and no high-risk factors or caries**	Posterior bitewing examination at 12-24 month intervals	Posterior bitewing examination at 24-36 month intervals	Not applicable
Peridental disease or history of periodontal treatment	Individualized radiographic examination consisting of selected periapical and/or bitewing radiographs for areas where periodontal disease (other than nonspecific gingivitis) can be demonstrated clinically		Not applicable
Growth and development assessment	Periapical or panoramic examination to assess developing third molar	Usually not indicated	Usually not indicated

**Patients at high risk for caries may demonstrate any of the following:

1. High level of caries experience

2. History of recurrent caries

3. Existing restoration of poor quality

4. Poor oral hygiene

5. Inadequate fluoride exposure

6. Prolonged nursing (bottle or breast)

7. Diet with high sucrose frequency

8. Poor family dental health

9. Developmental enamel defects

10. Developmental disability

11. Xerostoma

12. Genetic abnormality of teeth

13. Many multisurface restorations

14. Chemo/radiation therapy

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NOTE: The recommendations in the above charts are subject to clinical judgment and may not apply to every patient. They are to be used by licensed dentists only after reviewing the patient's health history and completing a clinical examination. The recommendations do not need to be altered because of pregnancy.

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SECTION XII - MOUNTING AND VIEWING RADIOGRAPHS

A. Dental film mounting

Dental films should be mounted on an opaque film mount with clean and dry hands to avoid scratching or smearing the film surface. For best results, thin, light cloth gloves can be worn in the performance of mounting dental films. Films should be handled by edges only. The use of a viewbox will facilitate correct mounting.

Some mounts have slots for holding each film, whereas other styles provide gummed paper to hold the radiographs. Because films may be placed in the mount in two ways, dental personnel should follow the routine established for the dental office. Films should always be placed in the

mount with the embossed dot up (toward the viewer) which provides a normal right to left view of the patient's dentition.

Films must be correctly identified with the patient's name and date of exposure.

B. Film viewing

Ideally, dental radiographs should always be viewed on a viewbox that is uniformly lit and that has a variable light intensity option. A magnifying glass should be available to facilitate the viewing of dental radiographs. Viewing should be done in a subdued room lighting and a template on the viewbox should be available to eliminate distracting light around the film mount.

C. Viewbox maintenance

The condition of the viewbox or illuminator has an effect on the perception of density and contrast of a dental radiograph. Variations or distortions can result from:

• Dirt on the Plexiglas
• Discoloration of the Plexiglas front
• Type or age of the illuminator bulb

As a bulb approaches the end of its useful life, it will begin to blacken. If this happens, the lamp should be replaced before it burns out. The entire bank of light should be replaced simultaneously and the illuminator fronts cleaned regularly as suggested by the manufacturer.

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SECTION XIII - OCCUPATIONALLY EXPOSED WOMEN OF CHILDBEARING AGE

California Radiation Control Regulations state that each licensed dentist must instruct occupationally exposed individuals (dental hygienists and dental assistants) in the health protection problems associated with radiation. A special situation arises with occupationally exposed young women. The precautions should be taken to limit exposure to young women, especially if they could be pregnant. Exposure to the abdomen of such workers to x-rays would involve radiation dose to the embryo or fetus.

Licensed dentists are responsible for the following:

• Following Nuclear Regulatory Commission Regulation requirements (10 CFR section 20.1208 (see XIII.A.2) incorporated in California Regulations by reference) at Title 17, Section 30253.

• Providing individual or personal monitoring devices to occupationally exposed individuals of childbearing age and monitoring results for exposure to ensure that there is no excessive exposure. (See XIII.A.2.a)

• Providing the employee with reasons for the requirements. (See XIII.A.2.b.)

• Explaining the available options for protecting the embryo/fetus. (See XIII.A.2.c)

1. Definitions:

Declared pregnant woman means a woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date (month) of conception.

Deep-dose equivalent, which applies to external whole-body exposure, is the dose equivalent at a tissue depth of 1 cm (100 mg/cm).

Embryo/fetus means the developing human organism from conception until the time of birth.

2. Regulatory provisions (10 CFR 20, Section 20.1208):

a. The licensed dentist shall ensure that the dose to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, does not exceed 0.5 rem (5 mSv).

b. The licensed dentist shall make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman so as to satisfy the limit in paragraph (a) of this section.

c. The dose to an embryo/fetus shall be taken as the deep-dose equivalent to the declared pregnant woman.

d. If the dose to an embryo/fetus is found to have exceeded 0.5 rem (5 mSv), or is within 0.05 rem (0.5 mSv) of this dose, by the time the woman declares the pregnancy to the licensed dentist, the dentist shall be deemed to be in compliance with paragraph (a) of this section if the additional dose to the embryo/fetus does not exceed 0.05 rem (0.5 mSv) during the remainder of the pregnancy.

B. Reasons for requirements

Once a pregnancy becomes known, the radiation dose of the embryo-fetus shall be no greater than 0.05 rem (50 millirems) in any month (excluding medical exposure).

Some studies have shown that there is an increased risk of leukemia and other cancers in children if the expectant mother was exposed to a significant amount of radiation. Women employees must be aware of possible risks so they can take appropriate steps to protect their offspring.

It is strongly suggested that the instruction be given both orally and in writing. Also each woman employee should be given an opportunity to ask questions, and each woman employee should be asked to acknowledge in writing that the instruction has been received. Further, it would be prudent to keep records of such acknowledgment indefinitely.

The following facts should be given to the woman employee:

• The first three months of pregnancy are the most important as the embryo-fetus is most sensitive to radiation at this time.

• In most cases of occupational exposure, the actual dose received by the embryo-fetus is less than the dose received by the mother, because some of the dose is absorbed by the mother's body.

• At the present occupational dose equivalent limits, the risk to the unborn baby is considered to be small, but experts disagree on the exact amount of risk.

• There is no need for women to be concerned about sterility or loss of ability to bear children from occupational exposure.

• Once a pregnancy becomes known, radiation dose of the embryo-fetus shall be no greater than 0.05 rem (50 millirems) in any month.

• The 0.5 rem (500 millirems) dose equivalent limit applies to the full nine months of pregnancy.

• Temporary assignment to tasks which involve less risk of being exposed to radiation

• Use of protective apron (full-size, half-size, wrap-around, or any other protective clothing appropriate to the situation) while actually exposing patients

• Abiding by the regulatory prohibitions (see 10 CFR 20.1208, as noted in Section XIII.A.2)

• Use of monitoring devices such as a film badge worn at the abdomen

• Staying out of the x-ray room and behind the protective barrier during exposure

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SECTION XIV - DENTAL RADIATION PROTECTION - PROTECTIVE BARRIERS

The objective of dental radiography is to obtain diagnostic quality dental radiographs with minimum exposure to the patient, dental personnel and the public. Efforts toward these objectives include:

• Use of the fastest film (E-speed) or digital image receptors

• Maintenance and adherence to proper film processing

• Assurance of adequate and proper x-ray tube filtration, kVp, mA and timer accuracy through regular maintenance and calibration by a qualified service technician

• Operator protection (standing behind a protective barrier during exposure)

B. Barriers

Conventional building materials in walls, partitions, floor and ceiling may provide adequate shielding from x-radiation; however, there may be situations where lead shielding would be required due to workload, office design or other circumstances. The Radiologic Health Branch recommends that the shielding design for your particular situation be developed by a qualified expert, an individual knowledgeable in evaluating dental radiation protection requirements. A list of individuals and/or companies who perform such services is available from the Radiologic Health Branch:

Department of Health Services
Radiologic Health Branch
601 North 7th Street, MS-178, Post Office Box 942732
Sacramento, CA 94234-7320

Generally, a wall made of two layers of 5/8" offset gypsum board can be assumed to provide the minimum protection from scattered radiation if the following conditions are met:

1. Areas occupied by patients are protected by this wall or a wall of equivalent attenuating material, and there is at least a 6 feet distance between the dental x-ray chairs.

2. Dental personnel should be careful not to aim the primary beam toward areas adjacent to the x-ray room.

3. The use of dental x-ray equipment does not exceed the following operating parameters:

• 60 seconds/week of actual beam "on-time" at 90 kVp, or
• 100 seconds/week of actual beam "on-time" at 65 kVp

Los Angeles County: (213) 738-4059
Orange County: (714) 667-3605
San Diego County: (619) 694-2169

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SECTION XV - GLOSSARY OF TERMS PERTAINING TO DENTAL RADIOGRAPHY

Absorbed Dose: See Dose.

Absorption (differential, rare earth screen, specific rate of, visible light): The transfer of energy from an x-ray beam to the atoms or molecules of the matter through which it passes. The process whereby radiation is stopped and reduced in intensity as it passes through matter. Lead, which is denser than most materials, is one of the best absorber of x-rays.

Added Filter: See filter.

Aiming Cylinder: A round/circular metal tube/shield attached to the x-ray tube housing or placed in front of the x-ray tube to limit the size of the x-ray beam to a predetermined size and shape.

ALARA: An acronym for As Low As Reasonably Achievable, economic and social factors being taken into consideration. Relates to radiation dose to the patients, the public, and occupationally exposed individuals.

Aluminum Equivalent: The thickness of aluminum affording the same attenuation, under specified conditions, as the material in question.

Anode: A positive electrode, also referred to as a target, toward which electrons are accelerated from the cathode. The target is usually composed of tungsten.

Artifact: Any density or mark on a radiograph that is caused by something not belonging to the part being x-rayed.

Attenuation: The process by which an x-ray beam of radiation is reduced in intensity by absorption or scattering when passing through material.

Barrier: Protective: Barrier of attenuating materials used to reduce radiation exposure. Primary: Barrier sufficient to attenuate the useful beam to the required degree. Secondary: Barrier sufficient to attenuate stray radiation to the required degree.

Beam: A unidirectional flow of electromagnetic radiation.

Primary Radiation or X-Ray Beam: That part of the radiation which passes through the window, aperture, cone, or other collimating device of the tube housing. Also called "useful beam."

Bone Marrow: A soft tissue which constitutes the central filling of many bones and serves to produce red blood cells. Bone marrow is especially sensitive to x-rays.

Cataract: A clouding of crystalline lens of the eye which obstructs the passage of light.

Cathode: A negative electrode; electrode in the x-ray tube from which electrons are emitted. It consists of one or two filaments and focusing cup.

Centigray: 0.01 Gray (Gy). 1 cGy equals 1 rad.

Central Ray (Central Beam): Refers to the x-rays in the center of the useful or primary beam.

Characteristic Curve: A type of input-output curve used to express the change in density with the change in radiation dose (exposure) of the photographic or x-ray film. The slope of the straight line portion of this curve is called "gamma."

Chromosome: Important macromolecules found in all body cells. Chromosomes contain the genes of heredity-determining units.

Chronic Exposure: Irradiation which is spread out over a period of years. Those who are occupationally exposed to radiation can suffer from chronic exposure.

Collimator: A device for restricting/confining/limiting a beam of radiation within an assigned solid angle.

Compton Scatter Radiation: The incident radiation has sufficient energy to dislodge a bound electron, but attacks a loosely bound electron, dislodges the electron and the remaining radiation energy proceeds in a different direction as scatter radiation. Compton scatter radiation is the main process responsible for the dose of radiation the patient receives during a radiographic procedure.

Cone: A round/circular metal tube/shield attached to the x-ray tube housing or placed in front of the x-ray tube to limit the size of the x-ray beam to a predetermined size and shape.

Contrast: In radiology, contrast is defined as the difference in density between light and dark areas on the processed film.

Control Chart: A chart used to record and control the performance of a radiographic processor as a function of time.

Dead-Man Switch: A switch so constructed that a circuit-closing contact can be maintained only by continuous pressure by the x-ray operator on the switch.

Densitometer: An instrument used to measure film density which is the degree of blackening of film by measuring the ratio of the light intensity incident on the film to the light intensity transmitted by the film. (The densitometer is a device designed to measure the optical density of an exposed and processed film. It can measure the density of the individual steps on films exposed in a sensitometer, and is commonly used for daily processor quality control.)

Density: Film blackening (the amount of light transmitted through the film).

Detail (definition): In radiography, detail refers to the sharpness of structure lines or contour lines on the processed film.

Developer: The chemical solution (alkaline) used in film processing that makes the latent image visible.

Developer Replenishment: Developer replenishment is used to maintain the proper alkalinity, chemical activity, and level of solution in the developer tank.

Diagnostic Type Tube Housing: Means any x-ray tube housing so constructed that the leakage radiation at a distance of one meter from the target cannot exceed 100 millirads in one hour when the tube is operated at any of its specified ratings.

Diaphragm: A plate, usually lead, with a central aperture so placed as to restrict the useful x-ray beam. See Collimator.

Distortion: Unequal magnification of different portions of body area being x-rayed.

Dose: A general term denoting the quantity/amount of radiation or energy absorbed per unit mass. For special purposes it must be appropriately qualified as follows:

Absorbed Dose: The amount of energy imparted by ionizing radiation per unit mass of irradiated material. The units of absorbed dose are the rad (1 rad equals 100 ergs per gram, see Rad, and the Gray). The SI unit of absorbed dose is the Gray (Gy). 1 Gy = 1 joule/kg. There are 100 rads per Gy.

Dose Equivalent: Means the product of the absorbed dose in tissue, quality factor, and all other necessary modifying factors at the location of interest. The unit of dose equivalent are the rem and the Sievert (Sv). 1 rem = 0.01 Sv.

Dose rate: Absorbed dose (or dose equivalent)delivered per unit of time.

Dosimeter: An instrument to detect and measure accumulated radiation dose (exposure).

Personnel Dosimetry: The use of instruments and associated procedures (including calibration and quality assurance) to ascertain the radiation dose absorbed by personnel.

Personnel Dosimeters: Devices designed to be worn or carried by an individual for the purpose of determining the dose equivalent received [for example: film badge, pocket chamber, pocket dosimeter, ring badges, thermoluminescent (TLD) badges, etc.].

Emulsion: The sensitive layer of photographic or x-ray film containing a silver compound in a layer of gelatin.

Exposure or Irradiation Time: The time interval in a radiological examination within which x-rays are incident upon the body part under examination.

Film Badge: A personnel monitoring device which measures radiation exposure and is used for personnel monitoring.

Film Speed: A relative exposure number needed to produce a density of 1.0 above gross fog - used for screen type, dental and medical x-ray films.

Filter/Filtration: Means material placed in the primary or useful x-ray beam to absorb preferentially the less penetrating radiations. The use of appropriate filtration prevents the patient from receiving unnecessary radiation dose.

Added Filter: Sheets of metal (usually aluminum or its equivalent) which are placed in the direct path of the x-ray beam.

Inherent Filter: The x-ray tube and its housing such as the glass envelope (window) through which the x-ray beam passes.

Total Filtration: The sum of the inherent and added filters.

Fixer: A chemical solution (acidic) which removes the unexposed and underdeveloped silver halide crystals from the film so it will not discolor or darken with age or exposure to light. Fixer also hardens the gelatin containing the black metallic silver so film may be dried and resist damage from abrasions.

Fixer Retention: The inadequate removal of fixer from the film by the water in the wash tank of the processor. Retained fixer causes eventual brown discoloration of the radiograph.

Focal Spot: A small area on the target of the anode toward which the electrons from the focusing cup of the cathode are directed. X-radiation originates at the focal spot.

Effective Focal Spot: The apparent size of the radiation source when viewed from the central axis of the useful beam.

Fog or Fogging: A cloudy appearance of the finished radiograph caused by several factors such as old or contaminated processing solutions, exposure to chemical fumes, faulty darkroom safelight, or scatter radiation.

Geometric Unsharpness: Unsharpness of the recording image due to the combined optical effect of finite size of the radiation source and geometric separation of the anatomic area of interest from the image receptor and the collimator.

Gonad Shielding: Devices used during radiographic procedures to protect the reproductive organs from exposure to the useful x-ray beam.

Gray (Gy): The SI unit of absorbed dose equal to an energy deposition of 1 joule/kg = 10,000 ergs/gm (1 Gy = 100 rads).

H & D Curve: See Characteristic Curve.

Half-Value Layer (HVL): The thickness of a specified substance/material (usually aluminum, copper - for x-ray beam quality, or lead - for shielding purposes) which, when introduced into the path of a given beam of radiation reduces the exposure rate by one-half.

Health Physics: The science of protecting human beings from injury by radiation, and promoting better health through beneficial applications of radiation. (Also called Radiological Health).

Individual: Any human being.

Installation: The location where one or more reportable sources of radiation are possessed (located).

Intensifying Screens: Devices which increase the brightness of the image produced by the action of x-rays upon a phosphor.

Inverse Square Law: The intensity of the radiation is inversely proportional to the square of the distance from the source.

Ion: An atom or molecule which has one or more of its surrounding electrons separated from it and therefore carries a positive electric charge, or a free electron carrying a negative electrical charge.

Ion/Ionization Chamber: An x-ray measuring device in which gas is ionized in proportion to the quantity of x-ray energy passing through the chamber.

Ionization: The process whereby one or more electrons is removed from a neutral atom by the action of radiation (the conversion of atoms to ions).

Kilovolt: A unit of electrical potential difference equal to 1,000 volts.

Kilovolt Peak (kVp): A unit of maximum or crest value of electrical potential difference between the anode and cathode of an x-ray tube. Kilovolt peak (kVp) determines the penetrating ability of x-rays and refers to the "quality" of x-rays.

Latitude: The property of an x-ray film to have a great number of units of density produced within certain log-relative exposure numbers; longer latitude films have lower contrasts.

Lead Equivalent: The thickness of lead affording the same attenuation, under specified conditions, as the material in question.

Leakage Radiation: Means all radiation coming from within the x-ray tube housing except the useful beam.

Leukemia: A blood disease which is characterized by overproduction of white blood cells. It may result from overexposure of the bone marrow to radiation.

Magnification: The ratio of image size to object size. The image may be larger than, smaller than, or equal to the object; so magnification can be greater than, equal to, or less than 1.

Milliampere (mA): The electron current (measured in milliamperes) flowing across the x-ray tube from the cathode to the anode. Milliampere (mA) multiplied by the time during which the beam strikes an object (measured in seconds) is milliampere-seconds (mAs) and is a measure of the "quantity" of x-rays.

Millirad (mrad): A division of the rad, equal to one one-thousandth of a rad. See Rad.

Millirem (mrem): A division of the rem, equal to one one-thousandth of a rem. See Rem.

Mutation: A transformation of the gene which may be induced by radiation and may alter characteristics of the offspring.

Occupational Dose: Means the dose received by any individual in the course of employment. Exception: Radiation dose received for the operator's own personal medical or dental diagnosis or therapy.

Operator's Station: The area where the control panel for the operation of an x-ray machine is located. The operator's station at the control shall be behind a protective barrier either in a separate room, in a protective booth, or behind a shield which will intercept the useful beam and any radiation which has been scattered only once.

Phantom: An object used to simulate the absorption and scatter characteristics of the patient's body for radiation measurement purposes.

Photoelectric Absorption: An interaction between an x-ray photon and an inner shell electron in which the photon surrenders all of its kinetic energy to the electron and ceases to exist. The atom responds by ejecting the electron from the inner shell. Photoelectric absorption is one of the processes responsible for the dose of radiation the patient receives during a radiographic procedure.

Photon: A quantity of energy emitted in the form of electromagnetic radiation. X-rays are examples of photons.

Pointer Cone: A means used to indicate the direction of the useful beam and to establish the minimum source-surface distance. It may be a cylinder or a cone and must be open ended.

Quality: A term used to describe the penetrating power of x-rays and is related to the energies of the photons in the useful or primary x-ray beam.

Quality assurance (QA): Quality Assurance (QA) is a management tool that includes policies and procedures designed to optimize the performance of facility personnel and equipment.

QA includes all of the following:

• Quality control (QC)
• Administration
• Education of personnel
• Preventive maintenance methods

Quality Control (QC): Quality Control (QC) refers to routine performance and interpretation of test equipment function and to corrective action needed and taken.

Quantity: A term used to describe the number of photons in an x-ray beam.

Rad: The rad is the unit of absorbed dose. One rad is the dose corresponding to the absorption of 100 ergs per gram. (A special unit of absorbed dose and the specific energy imparted. One rad is 0.01 joules per kilogram of any material. The Gray (Gy) the SI unit of absorbed dose.)

Radiograph: A film or other recording produced by the action of x-rays transmitted through the patient.

Radiography: Utilizing ionizing radiation, this technique involves making shadow images on photographic emulsions. The image is the result of differences in attenuation of the radiation as it passes through the object in its path

Rem: The rem is the special unit of any of the quantities expressed as dose equivalent. The dose equivalent in rems is equal to the absorbed dose in rads multiplied by the quality factor (1 rem = 0.01 Sievert).

Repeats/Retakes: Additional radiographs taken because of technical or mechanical error. These lead to increased radiation exposure for the patient and the radiation worker and should be avoided.

Resolution: The process or capability of distinguishing closely adjacent optical images.

Resolving Power: This term refers to the ability to distinguish separate images of line pairs (lines and spaces) per millimeter.

Scattered Radiation: Means radiation that, during passage through matter, has been deviated in direction. It usually has also been modified by a decrease in energy.

Secondary or Stray Radiation: Means radiation not serving any useful purpose. It includes leakage and scattered radiation.

Sensitometer: An instrument used to expose film to precisely controlled steps of increasing light intensity.

Sensitometry: The act, the art, or the science of measuring sensitivity, as of photographic material or x-ray film.

Shield/Shielding: Material which is interposed between a radiation source and an irradiated site for the purpose of minimizing the radiation hazard (used to prevent or reduce the passage of radiation). Shielding is usually made of lead which is dense and absorbs radiation easily. Shielding is often used to protect the reproductive organs, testes or ovaries, from the x-ray beam during an examination.

Sievert (Sv): The SI unit of dose equivalent equal to the product of a dose of one Gray, the quality factor, and any other applicable modifying factors. (1 Sv = 100 rem).

Somatic: Pertaining to the body tissue other than reproductive cells.

Source-to-Image Distance (SID): The distance measured along the central ray from the center of the front of the surface of the source (x-ray focal spot) to the surface of the image detector.

Source-to-Skin Distance (SSD): The distance measured along the central ray from the center of the front surface of the source (x-ray focal spot) to the surface of the irradiated object or patient.

Speed Factor: With intensifying screens, the speed factor is defined as the ratio of the radiation dose (exposure) required without screens to the radiation dose (exposure) required with screens to get the same degree of blackening of x-ray films.

Step Wedge (Penetrometer): A device made up of different density filters shaped in a step- like form where each step or filter differs in density by the square root of 2.

Supervision: Supervision means responsibility for, and control of, quality, radiation safety, and technical aspects of all x-ray examinations and procedures.

Survey: Means an evaluation of the radiation hazards incident to the production, use, release, disposal, or presence of sources of radiation.

Target: Material at which electrons from the cathode in an x-ray tube are aimed in order to produce x-rays. See Anode.

Target-Film Distance: The distance from the x-ray tube target (anode) to the film measured in inches or centimeters.

Target-Skin Distance: The distance from the x-ray tube target (anode) to the skin of the patient where the x-ray beam enters the body.

Thermoluminescence: The property of certain inorganic crystals to emit light when heated following exposure to ionizing radiation. The quantity of light is related to the total absorbed dose.

Thermoluminescent Dosimetry (TLD): A dose measurement system utilizing certain inorganic crystals, such as lithium fluoride (LiF). Energy is accumulated by radiation induced dislocation of electrons. Upon heating the TLD material, the dislocated electrons return to their original locations releasing the stored energy in the form of light. The quantity of emitted light is proportional to the absorbed radiation.

Useful Beam: Means that part of the radiation which passes through the window, aperture, cone, or other collimating device of the tube housing.

X-Rays: Penetrating electromagnetic radiation whose wavelengths are shorter than those of visible light. For radiographic purposes, x-rays are usually produced by bombarding a metallic target with fast electrons in a vacuum.

X-ray Generator: A device which supplies electrical power to the x-ray tube. It does not, as the name implies, actually generate x-rays.

X-ray personnel: The following individuals are legally allowed to use diagnostic x-rays on human beings:

• Licensed dentists
• Individuals (dental hygienists and dental assistants) who have successfully completed a radiation safety course approved by the Board of Dental Examiners.

Return to Table of Contents

APPENDIX

Distributed by:

California Dental Association

RADIOLOGIC HEALTH BRANCH

The Radiologic Health Branch, within the California Department of Health Services, is responsible for administering the rules and regulations developed pursuant to the Radiation Control Laws (Sections 25800 - 25856, inclusive, of the California Health and Safety Code).

A. California Radiation Control Regulations.

Regulations relating to radiation control are found in Sections 30100 - 30146, inclusive, and Sections 30250 - 30313, inclusive, of the California Code of Regulations (CCR), Title 17.

B. 10 CFR 20 (Regulations of the Nuclear Regulatory Commission).

Regulations of the Nuclear Regulatory Commission are incorporated by reference in Section 30253, California Code of Regulations (CCR), Title 17.

Dental x-ray exposure cards.

The Radiologic Health Branch may conduct a survey of dental x-ray equipment by sending a "Dental X-Ray Exposure Card" that contains a thermoluminescent dosimeter (TLD). The card contains a small capsule TLD capable for measuring x-ray exposure of intraoral dental x-ray equipment. The card is to be returned to:

Department of Health Services
Radiologic Health Branch
601 North 7th Street, MS-178
Post Office Box 942732
Sacramento, CA 94234-7320
(916) 445-0931

BOARD OF DENTAL EXAMINERS AND THE COMMITTEE ON DENTAL AUXILIARIES

The Board of Dental Examiners, within the Department of Consumer Affairs, administers the laws and regulations pertaining to licensed dentists and dental auxiliaries (dental hygienists and dental assistants). The laws - Dental Practices Act - are found in Sections 1 to 1808 of the Business and Professions Code. The regulations are found in Sections 1000 to 1089, of the California Code of Regulations (CCR), Title 16. Relevant contacts are:

Department of Consumer Affairs
Board of Dental Examiners
1432 Howe Avenue, Suite 85
Sacramento, CA 95825
(916) 263-2300

Department of Consumer Affairs
Committee on Dental Auxiliaries
1428 Howe Avenue, Suite 58
Sacramento, CA 95825
(916) 263-2595

EXCERPTS FROM CALIFORNIA RADIATION CONTROL REGULATIONS

APPLICABLE TO THE PRACTICE IN DENTISTRY

California Code of Regulations (CCR), Title 17, Chapter 5. Subchapter 4

Article 1. Registration Procedure

30108. Registration Requirement.

Every person possessing a reportable source of radiation shall register with the Department in accordance with the provisions of Sections 30110 through 30146.

30110. Initial Registration.

(a) Every person not already registered who acquires a reportable source of radiation shall register with and pay the fee as specified in Section 30145 to the Department within 30 days of the date of acquisition.

(b) Every person who intends to acquire a radiation machine capable of operating at a potential in excess of 500 kVp shall notify the Department at least 60 days prior to his/her possession of the machine or at least 60 days prior to the commencement of construction or reconstruction of the room which will house the machine, whichever occurs first. This equipment shall not be used to treat patients until written approval of provisions for radiation safety has been obtained by the user from the Department.

(c) Every person who registers or renews a registration shall complete a separate registration form furnished by the Department for each separate installation.

30111. Renewal of Registration.

Registration for each source of radiation shall be renewed during July of every even-numbered year on a form furnished by the Department.

The registrant shall report in writing to the Department, within 30 days, any change in: registrant's name, address, location of the installation or receipt, sale, transfer, disposal or discontinuance of use of any reportable source of radiation.

(a) Any manufacturer, distributor, retailer, agent, or any other person who sells, leases, transfers or lends a radiation machine to any person who may be required to register such machine shall notify the Department on a form approved by the Department no later than 30 days after the end of each calendar quarter of:

(1) The names and addresses of persons who have received such machines.
(2) The manufacturer and model of each such machine.
(3) The date of transfer of each radiation machine.
(4) Other related information as may be required by the Department.

Article 3. Records

30131. Records to Be Maintained.

Every person who possesses a reportable source of radiation shall keep records showing the receipt (for any source received after June 30, 1962), transfer, or disposal of a reportable source of radiation.

Article 1. General

30252. Scope and Purpose.

(a) Group 3 regulations apply to all persons who possess sources of radiation, except as exempt from the licensing and registration requirements or otherwise specifically exempted by the provisions of Group 1 and Group 2 of this subchapter.

(b) The limits in Group 3 do not apply to doses due to background radiation, to exposure of patients to radiation for the purpose of medical diagnosis or therapy, or to voluntary participation in medical research programs.

30253. Standards for Protecting Against Radiation.

(a) The regulations governing standards for protection against radiation in the United States, Title 10, Code of Federal Regulations, Part 20, Sections 20.1001 through 20.2402 and Appendices A through F (revised January 1, 1993), are hereby incorporated by reference with the following exceptions:

(1) The following sections of Title 10, Code of Federal Regulations, sections, 20.1001, 20.1002, 20.1006, 20.1007, 20.1008, 20.1009, 20.2106(d), 20.2302, 20.2401, 20.2402 and Appendix D are not incorporated by reference.
(2) Any references to the United States Nuclear Regulatory Commission or any component thereof shall be deemed to be a reference to State Department of Health Services.

(6) The definition of the term "Licensee" as defined in title 10, Code of Federal Regulations, section 20.1003 is replaced by the definition of the term "User" as set forth in title 17, California Code of Regulations, section 30100.

Article 2. Notices, Instruction, and Reports to Workers; Inspections and Investigations

30255. Notices, Instructions, and Reports to Personnel.

(a) This section establishes requirements for notices, instructions, and reports by users to individuals engaged in work under a license or registration and options available to such individuals in connection with Department inspections of licensees or registrants to ascertain compliance with the provisions of the Radiation Control Law and regulations, orders, and licenses issued thereunder regarding radiological working conditions. The requirements in this section apply to all persons who receive, possess, use, own or transfer material licensed by or registered with the Department.

(b) Each user shall:

(1) Inform all individuals working in or frequenting any portion of a controlled area of the storage, transfer, or use of radioactive materials or of radiation in such portions of the controlled area; instruct such individuals in the health protection problems associated with exposure to such radioactive materials or radiation, in precautions or procedures to minimize exposure, and in the purposes and functions of protective devices employed; instruct such individuals in, and instruct them to observe, to the extent within their control, the applicable provisions of Department regulations and license conditions for the protection of personnel from exposures to radiation or radioactive materials occurring in such areas; instruct such individuals of their responsibility to report promptly to the licensee or registrant any condition which may lead to or cause a violation of department regulations or license conditions or unnecessary exposure to radiation or radioactive material, and of the inspection provisions of Section 30254; instruct such individuals in the appropriate response to warnings made in the event of any unusual occurrence or malfunction that may involve exposure to radiation or radioactive materials; and advise such individuals as to the radiation exposure reports which they may request pursuant to this section. The extent of these instructions shall be commensurate with potential radiological health protection problems in the controlled area.
(2) Conspicuously post a current copy of this regulation, a copy of applicable licenses for radioactive material, and a copy of operating and emergency procedures applicable to work with sources of radiation. If posting of documents specified in this paragraph is not practicable the user may post a notice which describes the document and states where it may be examined.
(3) Conspicuously post a current copy of Department Form RH-2364 (Notice to Employees) in a sufficient number of places to permit individuals working in or frequenting any portion of a controlled area to observe a copy on the way to or from such area.

(6) Provide reports to any individual of his radiation exposure data and the results of any measurements, analyses, and calculations of radioactive material deposited or retained in the body of that individual as specified in this section. The information reported shall include data and results obtained pursuant to Department regulations, orders, or license conditions, as shown in records maintained by the user pursuant to Department regulations. Each notification and report shall: be in writing; include appropriate identifying data such as the name of the user, the name of the individual, the individual's Social Security number; include the individual's exposure information; and contain the following statement:

"This report is furnished to you under the provisions of the California State Department of Health Services Regulations: Standards for Protection Against Radiation. You should preserve this report for future reference."

(A) At the request of any individual, each user shall advise such individual annually of his exposure to radiation or radioactive material as shown in records maintained by the licensee or registrant pursuant to United States, Title 10, Code of Federal Regulations, Part 20, Subpart M as incorporated by reference in Section 30253, including the results of any calculations and analyses of radioactive material deposited in the body of the individual.
(B) At the request of an individual formerly engaged in work controlled by the user, the user shall furnish to the individual a report of his exposure to radiation or radioactive material. Such report shall be furnished within 30 days from the time the request is made, or within 30 days after the exposure of the individual has been determined by the user, whichever is later; shall cover, within the period of time specified in the request, each calendar quarter in which the individual's activities involved exposure to radiation from radioactive materials licensed by, or radiation machines registered with the Department; and shall include the dates and locations of work under the license or registration in which the individual participated during this period.
(C) When a user is required pursuant to United States, Title 10, Code of Federal Regulations, Part 20, Subpart M as incorporated by reference in Section 30253 to report to the Department any exposure of an individual to radiation or radioactive material, the user shall also provide the individual a report on his exposure data included therein. Such reports shall be transmitted at a time not later than the transmittal to the Department.
(D) At the request of an individual who is terminating employment or assignment to work involving radiation exposure in the user's facility in a given calendar quarter, the user shall furnish to the individual a written report of the individual's exposure to radiation or radioactive material received during that specifically identified calendar quarter. Such report shall contain an estimate of exposures if the final reports are not available at the time of termination. Estimated exposures shall be clearly indicated as such.

Article 4. Special Requirements for the Use of X-Ray in the Healing Arts

30305. General Provisions.

(a)

(1) This article pertains to use of X-rays in medicine, dentistry, osteopathy, chiropractic, podiatry, and veterinary medicine. The provisions of this article are in addition to, and not in substitution for, other applicable provisions of this regulation and of Group 1 of this subchapter.
(2) Any existing machine or installation need not be replaced or substantially modified to conform to the requirements of this regulation provided that the user demonstrates to the Department's satisfaction achievement of equivalent protection through other means.
(3) No person shall make, sell, lease, transfer, lend, or install X-ray or fluoroscopic equipment or the supplies used in connection with such equipment unless such supplies and equipment, when properly placed in operation or properly used, will meet the requirements of this regulation. This includes responsibility for the delivery of cones or collimators, filters, adequate timers and fluoroscopic shutters (where applicable).
(4) For X-ray equipment manufactured after July 31, 1974, the user shall provide sufficient maintenance to keep the equipment in compliance with all applicable radiation protection sections of the Code of Federal Regulations, Title 21, Chapter 1, Subchapter J, Part 1020, Sections 1020.30, 1020.31, and 1020.32.
(5) Each installation shall be provided with such primary barriers and/or secondary barriers as are necessary to ensure compliance with United States, Title 10, Code of Federal Regulations, Part 20, Subpart M as incorporated by reference in Section 30253. Special requirements are contained in Title 24, California Administrative Code, Sections 2-9102 through 2-9105.

(1) The user shall assure that all X-ray equipment under his jurisdiction is operated only by persons adequately instructed in safe operating procedures and competent in safe use of the equipment.
(2) The user shall provide safety rules to each individual operating X-ray equipment under his control, including any restrictions of the operating technique required for the safe operation of the particular X-ray apparatus, and require that the operator demonstrate familiarity with these rules.
(3) No user shall operate or permit the operation of X-ray equipment unless the equipment and installation meet the applicable requirements of these regulations and are appropriate for the procedures to be performed.
(4) Deliberate exposure of an individual to the useful beam for training or demonstration purposes shall not be permitted unless there is also a medical or dental indication for the exposure and the exposure is prescribed by a physician or dentist.

CAUTION

X-RAY

in lieu of other signs required by the United States, title 10, Code of Federal Regulations, part 20, section 20.1902 as incorporated by reference in section 30253.

(d) High radiation areas caused by radiographic or fluoroscopic machines used solely in the healing arts and which are in compliance with the access control and signal requirements of title 24, California Code of Regulations, sections 9102 through 9105 shall be exempt from the access control and signal requirements of the United States, title 10, Code of Federal Regulations, part 20, Section 20.1601 as incorporated by reference in section 30253.

30311. Dental Radiographic Installations.

(a) Equipment.

(1) The tube housing shall be of diagnostic type.
(2) Diaphragms or cones shall be used for collimating the useful beam and shall provide the same degree of protection as the housing.
(A) For intra-oral radiography the useful beam shall be restricted to a diameter of not more than 7 cm (2.75 inches) at the surface of the skin.
(3) For intra-oral film exposures a cone or spacer frame shall provide a target-to-skin distance of not less than 18 cm (7 inches) with apparatus operating above 50 kVp or 10 cm (4 inches) with apparatus operating at 50 kVp or below.
(4) The total filtration permanently in the useful beam shall be equivalent to at least 0.5 millimeters of aluminum for equipment operating below 50 kVp, equivalent to at least 1.5 millimeters of aluminum for equipment operating from 50 kVp through 70 kVp, and equivalent to at least 2.5 millimeters of aluminum for equipment operating above 70 kVp.
(5) A device shall be provided to terminate the exposure after a pre-set time or exposure.
(6) The exposure control switch shall be of the dead-man type. If a recycling timer is employed it shall not be possible to make a repeat exposure without release of the exposure switch to reset the timer.
(7) Each installation shall be provided with a protective barrier for the operator or shall be so arranged that the operator can stand at least 6 feet from the patient and well away from the useful beam.
(8) Mechanical support of the tube head and cone shall maintain the exposure position without drift or vibration.
(9) Panoramic installations. This part applies to those installations which consist of a tube head with a collimator providing a narrow useful beam and an extra oral film carrier which are interlocked in their motion about the patient. (A) All provisions of Section 30311 (a) apply except 30311 (a)(2)(A), 30311 (a)(3), 30311 (a)(10).
(10) Cephalometric installations.
(A) All provisions of Section 30311 (a) apply except 30311 (a)(2)(A), 30311 (a)(3), and 30311 (a)(9). (B) The radiographic field shall be restricted to the area of the image receptor.
(11) The X-ray control panel shall include means for indicating X-ray tube voltage (kVp), tube current (mA), and exposure duration. The tube voltage and current shall be indicated by meters or by control settings. A milliammeter, a light or other device shall give clear and distinct visual or audible indication to the operator when X-rays are being produced.

(1) No individual occupationally exposed to radiation shall be permitted to hold patients or films during exposure, nor shall any individual be regularly used for this service.
(2) During each exposure, the operator shall stand at least 6 feet from the patient or behind a protective barrier.
(3) Only the patient shall be in the useful beam.
(4) Neither the tube housing nor the position indicating device (cone, cylinder) shall be hand-held during exposure.
(5) Fluoroscopy shall not be used in dental examinations.
(6) Each patient undergoing dental radiography shall be draped with a protective apron of not less than 0.25 millimeter lead-equivalent to cover the gonadal area.

(7) For intra-oral and cephalometric radiography the X-ray beam and the film shall be aligned very carefully with the area to be radiographed.
(8) Only persons required for the radiographic procedure shall be in the radiographic room during exposures.

Section 20.1101. Radiation protection programs.

(a) Each licensee shall develop, document, and implement a radiation protection program commensurate with the scope and extent of licensed activities and sufficient to ensure compliance with the provisions of this part. (See Section 20.2102 for recordkeeping requirements relating to these programs.)

(b) The licensee shall use, to the extent practicable, procedures and engineering controls based upon sound radiation protection principles to achieve occupational doses and doses to members of the public that are as low as is reasonably achievable (ALARA).

(c) The licensee shall periodically (at least annually) review the radiation protection program content and implementation.

Section 20.1201. Occupational dose limits for adults.

(a) The licensee shall control the occupational dose to individual adults, except for planned special exposures under Section 20.1206, to the following dose limits.

(1) An annual limit, which is the more limiting of-- (i) The total effective dose equivalent being equal to 5 rems (0.05 Sv); or (ii) The sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue other than the lens of the eye being equal to 50 rems (0.5 Sv).
(2) The annual limits to the lens of the eye, to the skin, and to the extremities, which are: (i) An eye dose equivalent of 15 rems (0.15 Sv), and (ii) A shallow-dose equivalent of 50 rems (0.50 Sv) to the skin or to any extremity.

(f) The licensee shall reduce the dose that an individual may be allowed to receive in the current year by the amount of occupational dose received while employed by any other person (see Section 20.2104(e)).

Section 20.1207. Occupational dose limits for minors.

The annual occupational dose limits for minors are 10 percent of the annual dose limits specified for adult workers in Section 20.1201.

Section 20.1208. Dose to an embryo/fetus.

(a) The licensee shall ensure that the dose to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, does not exceed 0.5 rem (5 mSv). (For recordkeeping requirements, see Section 20.2106.)

(b) The licensee shall make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman so as to satisfy the limit in paragraph (a) of this section.

(c) The dose to an embryo/fetus shall be taken as the sum of--

(1) The deep-dose equivalent to the declared pregnant woman; and
(2) The dose to the embryo/fetus from radionuclides in the embryo/fetus and radionuclides in the declared pregnant woman.

Subpart D Radiation Dose Limits for Individual Members of the Public

Section. 20.1301. Dose limits for individual members of the public.

(a) Each licensee shall conduct operations so that--

(1) The total effective dose equivalent to individual members of the public from the licensed operation does not exceed 0.1 rem (1 mSv) in a year, exclusive of the dose contribution from the licensee's disposal of radioactive material into sanitary sewage in accordance with Section 20.2003, and
(2) The dose in any unrestricted area from external sources does not exceed 0.002 rem (0.02 mSv) in any one hour.

Section 20.1302. Compliance with dose limits for individual members of the public.

(a) The licensee shall make or cause to be made, as appropriate, surveys of radiation levels in unrestricted and controlled areas and radioactive materials in effluents released to unrestricted areas and controlled areas to demonstrate compliance with the dose limits for individual members of the public in Section 20.1301.

Section 20.1502. Conditions requiring individual monitoring of external and internal occupational dose.

Each licensee shall monitor exposures of radiation and radioactive material at levels sufficient to demonstrate compliance with the occupational dose limits of this part. As a minimum--

(a) Each licensee shall monitor occupational exposure to radiation and shall supply and require the use of individual monitoring devices by--

(1) Adults likely to receive, in 1 year from sources external to the body, a dose in excess of 10 percent of the limits in Section 20.1201(a).
(2) Minors and declared pregnant women likely to receive, in 1 year from sources external to the body, a dose in excess of 10 percent of any of the applicable limits in Section 20.1207 or Section 20.1208, and
(3) Individuals entering a high or very high radiation area.

Section 20.2101. General provisions.

(a) Each licensee shall use the units: curie, rad, rem, including multiples and subdivisions, and shall clearly indicate the units of all quantities on records required by this part.

(b) the licensee shall make a clear distinction among the quantities entered on the records required by this part (e.g., total effective dose equivalent, shallow-dose equivalent, eye dose equivalent, deep-dose equivalent, committed effective dose equivalent).

Section 20.2102. Records of radiation protection programs.

(a) Each licensee shall maintain records of the radiation protection program, including:

(1) The provisions of the program; and
(2) Audits and other reviews of program content and implementation.

Section 20.2106. Records of individual monitoring results.

(a) Record keeping requirement. Each licensee shall maintain records of doses received by all individuals for whom monitoring was required pursuant to Section 20.1502, and records of doses received during planned special exposures, accidents, and emergency conditions. These records must include, when applicable--

(1) The deep-dose equivalent to the whole body, eye dose equivalent, shallow-dose equivalent to the skin, and shallow-dose equivalent to the extremities; and
(2) The estimated intake or body burden of radionuclides (see Section 20.1202); and
(3) The committed effective dose equivalent assigned to the intake or body burden of radionuclides; and
(4) The specific information used to calculate the committed effective dose equivalent pursuant to Section 20.1204(c); and
(5) The total effective dose equivalent when required by Section 20.1202; and
(6) The total of the deep-dose equivalent and the committed dose to the organ receiving the highest total dose.

(c) Record keeping format. The licensee shall maintain the records specified in paragraph (a) of this section on NRC Form 5, in accordance with the instructions for NRC Form 5, or in clear and legible records containing all the information required by NRC Form 5.

(d) Privacy protection. (Not included in State regulations.)

(e) The licensee shall maintain the records of dose to an embryo/fetus with the records of dose to the declared pregnant woman. The declaration of pregnancy shall also be kept on file, but may be maintained separately from the dose records.

(f) The licensee shall retain each required form or record until the Commission terminates each pertinent license requiring the record.

Section 20.2107. Records of dose to individual members of the public.

(a) Each licensee shall maintain records sufficient to demonstrate compliance with the dose limits for individual members of the public (see Section 20.1301).

(b) The licensee shall retain the records required by paragraph (a) of this section until the Commission terminates each pertinent license requiring the record.

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