MN Dept. of Health Ionizing Radiation Rules. Chapter Highlights Pertaining to Dentistry

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2 MN Dept. of Health Ionizing Radiation Rules. Chapter 4730 Highlights Pertaining to Dentistry

3 Safety Requirements Only licensed practitioners of the healing arts or individuals who are qualified under statues of Minnesota Board of Dentistry may apply radiations. Students of healing arts, including dental hygiene and dental assisting are exempt from this requirement. Mechanical patient holding devices shall be used when technique permits.

4 Safety Requirements Exposure of individuals other than the patient when auxiliary support for patient or film holding is necessary: No unnecessary person allowed in the X ray room during exposure No part of the body of the staff and ancillary personnel, including hands to be in the useful beam or exposed to scatter radiation, unless protected by at least 0.5 mm of lead equivalent material (apron and gloves). No individual shall be used routinely to hold films or patients.

5 Safety Requirements Written safety procedures for patient and film holding must be provided Intensifying screens shall be used (in combination with the compatible film) with the exception of dental intraoral films

6 Safety Requirements Gonadal Protection: Except for cases in which it would interfere with the diagnostic procedure, gonadal protection of at least 0.5 mm lead equivalence is mandatory for patients who have procreative potential for radiographic procedures in which the gonads are in or within 2.0 inches (5.0 cm) of the useful beam. This implies that the use of gonadal protection (lead aprons) during dental intraoral and maxillofacial extraoral radiography is NOT MANDATED under the "Rules

7 Safety Requirements Lead aprons and gloves (if used) to be checked biennially for cracks. Records maintained on results Darkroom must be light tight. Proper safelight filters must be used. The request for radiographic examination can be made only by a licensed practitioner.

8 Safety Requirements The request for a radiographic examination must include clearly stated clinical indications for the examination. Intraoral film holders and bite blocks must be used. Film must not be routinely held by hand.

9 Safety Requirements No individual shall be used routinely to hold intraoral film, film cassettes, or patients. In those cases where the patient must hold film cassette, any portion of the body, other that the area of clinical interest, must be covered by not less than 0.5 mm lead equivalent material. This implies that for extraoral radiography in the dental office, i.e. for lateral jaw radiography or other extraoral radiography where the cassette is hand held by the patient, the patient must wear lead gloves on the hand that holds the cassette.

10 Safety Requirements Radiation Safety Officer (RSO): Must be designated by the owner/registrant Must be a licensed practitioner or qualified by training and experience concerning all hazards and precautions Duties: Establish a detailed radiation safety program Give instructions concerning hazards and safety practices for individuals under supervision who may be exposed to radiation Perform (or have performed) radiation safety surveys

11 Safety Requirements Radiation Safety Officer (RSO): Duties (cont.): Provide initial training and annual retraining of employees. The training should include information on: The effects of radiation exposure to the human body and embryo/fetus safe operating procedures for the facility Provide written safety procedures. Provide and monitor personnel dosimetry (when necessary)

12 Safety Requirements Radiation Safety Officer (RSO): Duties (cont.): Establish policy, protocol, and procedures for human holders. Establish policy and procedures for shielding of operators and patients Ensure that there is documentation of all formal instruction, test results, calibrations, safety surveys, equipment performance tests, and maintenance or x ray equipment and radiographic processors.

13 Equipment and Use Minimum source to skin distance in intraoral radiography must be 7.1 inches. Minimum source to skin distance in extraoral radiography must be 11.8 inches. Collimation, Dental: circular beam diameter at skin: 2.76" rectangular beam at skin: longer side 2.0" or less

14 Equipment and Use Half value layer (HVL), Beam Filtration: Minimum 1.5 mm aluminum equivalent for dental units operating at or below 70 kvp HVL must be in accordance with the following table: kvp Filtration up to

15 Equipment and Use Leakage radiation: Must not exceed 100 mr/hr (25.8 micro C/kg) when measured at a distance of 1 meter in any direction form source when tube head is operated at maximum kvp and ma. Tube head and cone must be stable during exposure. Must not be hand held during exposure.

16 Equipment and Use Must display warning label at control panel: "Warning: This X ray unit may be dangerous to patient and operator unless safe exposure factors and operating instructions are observed." Exposure factors, i.e. kvp, exposure time, etc. must be indicated before exposure begins. Permanent markings for fixed kvp and ma are acceptable

17 Equipment and Use Timers must: automatically terminate exposure after preset time, impulses, or mas not expose when set at "0" automatically reset after termination of exposure be reproducible

18 Equipment and Use X ray exposure control must: be "Dead man" type (requires continuous pressure) be of sufficient length to permit operator to be at least 6 feet from the tube and the patient provide visual indication of exposure termination from operator's position provide a signal audible to operator that the exposure has terminated (for machines installed after August 1974)

19 Equipment and Use The exposure at the end of the cone must not exceed the values listed in this table (air doses): D Speed Film E Speed Film kvp (milliroentgens) (milliroentgens) ( msv)

20 Equipment and Use A radiographic technique chart must be provided in the vicinity of the control panel. View boxes must be kept clean and be of uniform intensity. Bulbs must be of the same color.

21 Structural Shielding Each radiographic installation shall be provided with such primary or secondary barriers as are necessary to assure safety. For dental radiographic facilities, shielding must meet the criteria in National Council on Radiation Protection (NCRP) Report #145 Radiation Protection in Dentistry," (2004).

22 Structural Shielding When dental intraoral machines are installed in adjacent rooms or areas, protective barriers must be provided between the rooms or areas. Each installation must be provided with a protective barrier for the operator or must be arranged so that the operator can stand at least 6 feet from the patient and the tube head and not in the path of the useful beam.

23 Prohibitions No individuals shall be exposed to the useful beam except for healing arts purposes and only if authorized by a licensed practitioner. Exposure for training, instruction, and demonstration or other non healing arts purposes is forbidden. Exposure for the purpose of healing arts screening is forbidden (unless specifically approved by the commissioner).

24 Prohibitions Dental fluoroscopic imaging devices are forbidden. Intraoral radiography with kilovoltage 50 or under is forbidden. Unauthorized exposure of personnel monitoring equipment (i.e. to deceptively indicate a dose delivered to an individual) is forbidden. The use of direct exposure X Ray film (without intensifying screens) for all procedures except intraoral radiography is forbidden.

25 Registration Must register all sources of ionizing radiations within 30 days of acquisition on prescribed forms. Notify MDH about disposal or change in ownership. No advertisement pertaining to registration permitted. Biennial renewal. Registration must be renewed when address changes from one county to another. Theft or loss must be reported to the Commissioner of Health immediately.

26 Vendor s Responsibility No person shall make, sell, lease, transfer, lend, or install X ray equipment or the supplies unless these meet the requirements of the "Rule." Sale, lease, or transfer must be notified to the Commissioner of Health in writing within 30 days indicating name and address of purchaser.

27 Inspection Each registrant must allow the Commissioner of Health, at all reasonable times, to inspect radiation sources and the premises and facilities and must make available records required by this "Rule."

28 Permissible Doses Occupational Maximum permissible dose or dose equivalent (MPD) under the "Rules" means the maximum dose equivalents that persons shall be allowed to receive in a stated period of time. This excludes radiation received by the patient for diagnostic or therapeutic purposes and natural background radiation.

29 Permissible Doses Occupational Radiation Restricted Area (Occupational) One Calendar Quarter: 12.5 msv Cumulative: Age in years x 10 msv Pregnant Full term 5.0 msv Max per month 0.5 msv

30 Permissible Doses Occupational When a woman declares her pregnancy in writing and if her embryo or fetus has a potential of receiving greater than 1.25 msv during her entire pregnancy, the registrant must: 1. provide a dosimeter to be worn at the level of the abdomen and under any lead shielding worn; and 2. ensure that:(a) a reasonable effort is made to limit the dose to the embryo or fetus to 0.5mSv in any one month of pregnancy, and (b) the total effective dose equivalent to the embryo and fetus for a fullterm pregnancy does not exceed 5.0 msv.

31 Permissible Doses Occupational Minors: Exposure to individuals under 18 not permitted, except for training: per year, 1.0 msv Permissible Doses Public Annual continuous or frequent exposure: 1.0 msv

32 Personnel Monitoring Each registrant must supply the personnel with individual personnel monitoring dosimeters and require the personnel to wear the dosimeter under such circumstances that the individual receives, or is likely to receive, a dose in any calendar quarter over 25 percent of the applicable maximum permissible dose The registrant must maintain records of the dosimetry statements for the lifetime of the individual worker or a minimum of 30 years after termination of employment with the facility, whichever is less.

33 Personnel Monitoring Quarterly dosimetry report. A registrant must advise each worker at least quarterly of the worker s dose of radiation as shown in records maintained by the registrant. Report at end of employment. A registrant must furnish to a worker who is terminating employment, a report of the worker s dose of radiation. The report must be furnished within 30 days from the time of termination of employment.

34 Quality Assurance (QA) and Quality Control Quality Assurance refers to the measures taken to ensure that high quality films are produced consistently at minimum cost and minimum exposure to patient and operator. General quality assurance program procedures must be implemented and include a Quality Assurance Manual that contains written policies and procedures for radiation protection and describe the quality assurance program

35 Quality Assurance (QA) and Quality Control The quality assurance manual must include the following: The required tests and minimum performance criteria. Specifications for the minimum frequency of performance for the quality control tests. Test must be done after any change in the facility or equipment. The registrant and employees must be familiar with the contents and recommendations of any of the applicable publications listed on page 8 of the handout. The registrant may incorporate portions of the publications specified in this subpart into the facility's quality assurance manual.

36 Quality Assurance (QA) and Quality Control Radiation Safety Surveys: A survey must be performed at the time of the initial installation and after any change in the facility or equipment which might cause a change in radiation hazard All radiation safety surveys must be performed according to written procedures established by the radiation safety officer.

37 Quality Assurance (QA) and Quality In Service Education: Control Each registrant must provide in service training on quality assurance for employees. Employees must sign or initial their attendance on a record to be kept for inspection by the commissioner.

38 Quality Assurance (QA) and Quality Control Radiographic equipment and facility records must be maintained. This includes: Test results Repairs and Service Manufacturer and serial number or other identification number HVL and kvp at which HVL measurement was done

39 Quality Assurance (QA) and Quality Control Radiographic equipment and facility records must be maintained. This includes: Radiation safety survey including leakage measurements, calibrations, QC measurements, maintenance, and equipment modifications and names of those who performed the service. Personnel monitoring

40 Quality Assurance (QA) and Quality Control Quality Control Tests, Image Receptors: Screen film contact: annually Screen film Cassette speed match: annually

41 Quality Assurance (QA) and Quality Control Quality Control Tests, Automatic, Manual Processing: Darkroom fog: semi annually Processor Check: Densitometry and sensitometry, prior to the first patient film of the day. Film exposed on site at the time of the test Temperature Check, prior to the first patient film of the day. Follow manufacturer's recommendations.

42 Quality Assurance and Control QUALITY ASSURANCE is a plan of action to ensure that a diagnostic x ray facility will produce consistent, high quality images with a minimum of radiation exposure to patients and personnel. QUALITY CONTROL refers to the tests used for routine assessment of the basic performance of xray units, of manual and automatic processing of image receptors and viewing conditions.

43 Processor/Darkroom Processor Quality Control. Before any processor QC testing can be started, empty the chemicals and thoroughly clean the tanks as per manufacturer's instructions. Fill tanks with new chemicals mixed exactly to manufacturer's instructions. Before the first intraoral or extraoral patient film is exposed each day, the processor quality control tests must be performed. This is mandated by MDH regulations.

44 Daily: Processor/Darkroom A. Facilities with Intraoral Unit Only Manual or Automatic Processing. 1. Check Chemistry levels. Replenish with fresh Chemistry. Follow chemical manufacture's instructions. 2. Change rinse water. 3. Allow adequate warm up time (approximately minutes) before checking temp of developer. 4. Check temperature of the developer, use a hand held thermometer.

45 Daily: Processor/Darkroom 5. Expose test film. Before exposing test film, warmup x ray unit by pressing exposure switch twice. The instrument used is called "Dental Radiographic normalizing and monitoring device", also called "Crabtree device". Expose the film used in your clinic ("E" speed) using your usual kvp, ma and exposure time setting. Follow the instructions printed on the test device. NEVER EXPOSE TEST FILMS AHEAD OF TIME FOR FUTURE USE. Expose the day you intend to use them.

46 Daily: Crabtree Device

47 Daily. Crabtree Device

48 Daily. Processor/Darkroom 6. Process test film. Compare the processed film with the 7 step film strip provided with the device as a standard. The processed film should match the mid range of the standard film strip. If results are substandard, recheck xray unit settings and processor temperature. If both are correct, CHANGE CHEMICALS and repeat steps (3) through (6).

49 Daily. Densitometry

50 Daily. Processor/Darkroom 7. Record temperature and test results. Write date on the test film and save. 8. Keep 60 days of test films on hand for examination by Minnesota Dept. of Health. 9. All record must be maintained for 4 years.

51 Daily: Processor/Darkroom b. Facilities with Both Intraoral and Extraoral Units. Extraoral films is much more sensitive to processing changes than is intraoral film. Therefore, if you are processing extraoral films, Quality Control procedures are a bit different. 1. QC on the processor used for extraoral film requires the use of a step wedge. The is a medical aluminum wedge with at least 11 steps

52 Daily: Processor/Darkroom 2. Select a calibrated intraoral x ray machine to expose the film. USE THIS SAME X RAY MACHINE EACH TIME YOU EXPOSE THE STEP WEDGE. Lay the cassette on a flat surface, tube side up, and place the step wedge on the cassette with the long edge of the step wedge parallel to the long edge of the film cassette.

53 Daily: Processor/Darkroom 3. Position and center the x ray tube over the step wedge. The bottom of the tube housing should be approximately 30 inches from the cassette. Measure the distance and record it on your chart. THIS DISTANCE MUST BE EXACTLY THE SAME EACH TIME you expose the step wedge. If it is not, the results will not be valid. The use of approximately thirty inches will ensure that the field size at the film will cover the whole step wedge.

54 Daily QC. Extraoral

55 Daily: Processor/Darkroom 4. Exposure factors will vary depending upon the speed of the film screen combination being used. For example, a 400 speed film screen combination at 70 kvp, 15 ma and 8 impulses (2/15 seconds) will most often produce an image on the film with densities in the desired range. (Not too light or too dark.)

56 Daily: Processor/Darkroom 5. A density of approximately 1.0 O.D. (optical density units as measured on a densitometer) on a step in the middle of the wedge will provide the desired density range needed for checking processor quality control. However, without the availability of a densitometer, the newspaper method may be employed 6. Record on your chart the technique factors that produced the desired film densities. This will be THE TECHNIQUE USED EACH TIME YOU EXPOSE THE STEP WEDGE.

57 Daily: QC. Extraoral

58 Daily. Processor/Darkroom 7. Having established and recorded the appropriate technique which will produce the desired film, label the film "standard." This film now becomes your standard film for checking future step wedge films. 8. Glue a metal marker (e.g., paper clip or lead number) on the step that measures closest to 1.0 O.D. Some step wedges come with lead numbers on them record the number.

59 Daily. Processor/Darkroom 9. On a view box, compare the marked step of the new film to the marked step of the standard. If the densities are not the same, move the new film up or down to match the marked density on the standard. The difference between the marked step on the standard and the marked step on the new film should not be greater than one step in either direction. 10. If there is a difference of more than one step when comparing your films, you must find out why there is a difference and correct the problem(s).

60 Daily QC. Extraoral

61 Daily: Processor/Darkroom Some examples of possible problems: development time not correct, development temperature not correct, contaminated or exhausted chemicals, improper mixing of chemical solutions, darkroom fog, or standard exposure factors not used to make step wedge film. It is less likely that the x ray machine is malfunctioning, but possible.

62 Daily: Processor/Darkroom C. Facilities with Only Cephalometirc Unit: 1. Place the cassette in the ceph film holder and tape the step wedge vertically to the front of the cassette. 2. If the film holder is adjustable: A. Close the ear rods as much as possible B. Move the film holder as close to the ear rods as possible. Note the position of this set up and USE THE EXACT SAME POSITION EACH TIME YOU EXPOSE THE STEP WEDGE.

63 Daily QC: Cephalometric

64 Daily: Processor/Darkroom 4. Exposure factors will vary depending upon the speed of the film screen combination and distance being used. A starting point would be to use approximately 25% of a large, adult ceph technique. This will most often produce an image on the film with densities in the desired range. (Not too light or too dark.)

65 Daily. Processor/Darkroom 5. A density of approximately 1.0 O.D. (optical density units as measured on a densitometer) on a step in the middle of the wedge will provide the desired density range needed for checking processor quality control. However, without the availability of a densitometer, the newspaper method may be employed (see the Word document) 6. Having established and recorded the appropriate technique which will produce the desired film, label the film "standard." This film now becomes your standard film for checking future step wedge films.

66 Daily QC. Cephalometric

67 Daily. Processor/Darkroom 7. Glue a metal marker (e.g., paper clip or lead number) on the step that measures closest to 1.0 O.D. Some step wedges come with lead numbers on them record the number. 8. On a view box, compare the marked step of the new film to the marked step of the standard. If the densities are not the same, move the new film up or down to match the marked density on the standard. The difference between the marked step on the standard and the marked step on the new film should not be greater than one step in either direction.

68 Daily. Processor/Darkroom (9) If there is a difference of more than one step when comparing your films, you must find out why there is a difference and correct the problem(s). Some examples of possible problems: development time not correct, development temperature not correct, contaminated or exhausted chemicals, improper mixing of chemical solutions, darkroom fog, or standard exposure factors not used to make step wedge film. It is less likely that the x ray machine is malfunctioning, but possible.

69 Daily QC. Cephalometric

70 Daily. Processor/Darkroom d. Facilities with only a Panogram Unit: Due to the inconsistencies of the radiation exposure during the panogram's cycle, exposing the medical step wedge for processor quality control with the panogram is not recommended. Currently, facilities with only a panogram system will not be held to the processor quality control rule.

71 Weekly 1. High volume office Clean processor and do total Chemistry change. Used fixer must be recycled as per OSHA regulations. 2. Low volume office Clean processor and change chemicals every two to three weeks. Chemicals oxidize and age just from sitting in processor.

72 Semi annually. Darkroom Fog Darkroom Fog Test A. Facilities with Intraoral Units 1. Take an intraoral film packet (unexposed). 2. Go to the processor/darkroom hand tank area. 3. In the darkroom, unwrap the film packet. 4. Place the film where it would normally be during loading for processing, i.e., counter top. 5. Place a coin on the intraoral film.

73 Darkroom Fog Test: Intraoral

74 Semi annually. Darkroom Fog 6. Let this sit for two minutes, then process normally. 7. When completely processed, you should not be able to see the coin shadow on the film. 8. If you do, then you need to locate the source of the fog. Take corrective action, repeat testing until you have a clear film.

75 Darkroom Fog Test. Intraoral

76 Semi annually. Darkroom Fog b. Facilities with Extraoral units 1. Using the pan or ceph cassette loaded with film, you make a small exposure with your intraoral equipment. Exposure setting should be about 8 mas, 60 kvp using a 5 6 foot distance. If the intraoral equipment is a 70 kvp machine, then a lowering of the mas will be required. 2. Remove the film from the cassette in the dark room

77 Darkroom Fog Test. Extratraoral

78 Semi annually. Darkroom Fog 3. Place film on the counter and cover 1/2 the film with the cassette. 4. Let it sit like this for two minutes. Do make sure you step back so film is exposed to darkroom conditions without your shadowing the film. 5. When completely processed, you should not be able to distinctly see a difference from one side of the film to the other. 6. If you do, then you need to locate the source of the fog.

79 Darkroom Fog Test. Extratraoral

80 Darkroom Fog Test. Extratraoral

81 Darkroom Fog Test. Extratraoral

82 Darkroom Fog Test. Extratraoral

83 Darkroom Fog c. Recommendations for Eliminating Light Leaks in Dark Room 1. Turn off all lights in the dark room. 2. Let your eyes adjust to the dark for at least 5 minutes. 3. Look for light leaks 4. Mark light leaks with chalk 5. Seal light leaks with black masking tape or weather stripping 6. Use double doors or heavy curtains. 7. Keep all films for record.

84 Darkroom Fog d. Recommendation for Safe lighting 1. A KODAK GBX 2 Safelight Filter is recommended for use with both intraoral and extraoral films. 2. Place safelight at least 4 feet (1.2 m) away from working surface; a 15 watt lamp is recommended. 3. Check for cracked or faded filters, replace immediately if cracked. 4. Keep safe lighting exposure as short as practical

85 Annual. For Facilities with Extraoral a. Screen film contact test This test is done to check for screen film contact. 1. This evaluation requires a wire mesh test object. If a wire mesh is not available, the test object can be constructed by placing paper clips on an unexposed, processed panoramic film. Place paper clips in contact with each other in four rows, held in place by scotch tape. 2. Place the wire mesh test object on top of the film cassette on a flat surface. 3. Position the tube at a 40 inch focal film distance the C.R. should be perpendicular to the test object and cassette.

86 Film screen Contact. Wiremesh

87 Film screen Contact.

88 Annual. Screen film Contact Test 4. Make an exposure 10mA,0.25 sec., 70 kvp. Process the film. 5. View the processed radiograph in a dimly lit room on an xray view box at a distance of about 6 feet. 6. Area of poor contact will appear darker than areas of good contact. Cassettes that exhibit areas of poor contact should be replaced or re screened.

89 Film screen Contact. Wiremesh

90 Annual. For Facilities with Extraoral b. Screen film cassette Speed Match Test This test is done to ensure that all the screens of one type react to radiation exposure within a plus or minus 0.1 optical density to each other. The test works best with the use of a densitometer. However, if the densitometer is not available, density differences may be compared visually.

91 Annual.Screen film cassette Speed Match Test 1. Gather all the cassettes with screens of the same speed (regardless of size) and test these together. If the facility has only one cassette in a speed range, or has only one cassette, the speed match test is not required. 2. Pick a "Standard" cassette. Usually this is the newest one. 3. Place this cassette and three others with similar screens on the floor, corner to corner.(see Illustration) Film in same size cassettes should be from the same box.

92 Cassette Speed Match

93 Annual.Screen film cassette Speed Match Test 4. Number each cassette 5. Raise x ray tube to approximately 5 to 6 feet from the cassettes. Center over the 4 corners of the cassettes. Make an exposure using a technique to provide a density on the films of about 1.0 O.D. If you do not have a densitometer, use the newspaper method described before, 6. (6) Process all films. Compare each cassette film to the film identified as standard. Any visual difference in density will identify the cassette with a slower screen film combination. Repeat test films if you have varying densities. If repeat tests yield same results, pull slower cassette from service

94 Biannual. X ray Equipment Performance 1. Intraoral X ray units a. Filtration b. Radiation exposure at end of cone c. Timer reproducibility and accuracy d. kvp accuracy e. Reproducibility

95 Biannual. X ray Equipment Performance 2. Extraoral X ray units a. SID accuracy b. X ray and light field alignment c. X ray and bucky alignment d. Collimator dial accuracy f. mr/mas g. Linearity h. Timer accuracy i. Half value layer j. kvp accuracy k. Phototimer reproducibility (if present) e. Reproducibility