Guide for Radiation Safety/Quality Assurance Programs

Records of repairs and other pertinent data shall also be available. It is not essential that the records be stored in the room with the x-ray equipment tested but must be easily accessible to anyone who needs to use them.

  1. Test frequency - Each day of operation Equipment functioning: Each day during the x-ray generator warm-up, and before xraying the first patient, the operator should check for indicator dial malfunction and also the mechanical and electrical safety of the x-ray system. Malfunctions and unsafe conditions shall be corrected promptly. Suggestions for visual and manual checks are in Appendix H. Film processing: For each day of operation, the processing system must operate as close to the film manufacturer's temperature and speed recommendations of the product as possible. It is very important that corrective action be made when limits are exceeded or a pattern develops indicating a degradation of the system. Parameters to be included in processing checks:
    1. Speed Index or Medium Density:
      Control limits +/-0.15 Optical Density O.D.
    2. Contrast Index or Density Difference:
      Control limits +/-0.15 O.D.
    3. Base + Fog: Maximum density shall not exceed the established control limit by more than 0.03 O.D.

    Solution temperatures and replenishment rates should be checked when troubleshooting speed and contrast problems.

    1. Collimators
      1. Light field/X-ray Field alignment (App. C-1)
        The misalignment in either dimension of the edges of the light field versus the x-ray field shall not exceed 2% of the Source-Image-Distance (SID).
      2. Positive Beam Limitation (PBL) (App. C-2)
        The x-ray beam size shall not differ from the image receptor size by more than 3% of the SID in any one dimension or by a total of more than 4% of the SID in both dimensions.
      3. X-ray Field/Image Receptor alignment (App.C-3)
        The misalignment of the center of the x-ray field as compared to the center of the image receptor shall not exceed 2% of the SID.
      1. Image Receptor/X-ray Field alignment
        1. For image intensified equipment, the x-ray beam shall not exceed the visible area of the image receptor by more than 3% of the SID in one dimension or by a total of more than 4% of the SID in both directions.
        2. For non-certified image intensified equipment, the x-ray beam shall not exceed the visible area of the one/one spot film.
        3. For non-image intensified equipment, the x-ray field size shall not extend beyond the visible area of the image receptor.
        1. Radiographic Timer (includes Automatic Exposure Control)
          1. Reproducibility of the Output Radiographic units or spot film devices are in compliance, if in field testing, it can be shown that for four exposures at a specific time: Xmax - Xmin/Xavg ≤ 10% where X is an exposure measurement in mR. The most commonly used exposure time settings should be selected for testing. If the results of the four exposures are not compliant, make six additional exposures and calculate the coefficient of variation. The coefficient of variation of the exposure measurements shall be no greater than 0.05 and shall be determined by the equation: S/X ≤ 0.05, where X is the average of the exposure measurements and S is the standard deviation of the exposure measurements.
          2. Accuracy Certified equipment shall meet the manufacturers' specifications.
          1. Slice or tomographic cut level. The slice or cut level shall be within 5 mm of the indicated level.
          2. Slice or tomographic cut thickness. The slice or cut thickness with an arc setting of 30° shall have a slice thickness of 2.0 or 2.5 mm.
          3. Uniformity of Exposure For linear tomographic units, the exposure field using a pinhole trace, will demonstrate uniformity of exposure on both sides of the center of exposure. For complex motion tomographic units (elliptical, circular, hypo-cycloidal, trispiral, etc.) the pinhole exposure trace shall not indicate any area of large gaps in exposure on the trace pattern nor shall it show erratic motion.
          4. Resolution Each tomographic unit should be capable of resolving a #40 mesh pattern and shall be capable of resolving a #20 mesh pattern. Facilities with two or more tomographic units shall maintain those units so that the slice or tomographic cut level is the same for each unit. It is recommended that for such facilities, a Littleton or comparable phantom be used to evaluate tomographic systems, in particular, those systems performing complex motion.
          1. Spatial Resolution The spatial resolution of the fluoroscopic system shall be measured using a test tool composed of a line pair plate with discreet line pair groups and a maximum lead foil thickness of 0.1 mm or an equivalent device. The minimum spatial resolution at the center of the beam for a 6 inch field of view (FOV) is 2 line pairs per mm. The minimum spatial resolution for all other FOVs shall be determined by the following equation: 2 lp/mm x (6" (15 cm) FOV/size of the FOV used) = minimum number of lp/mm.
          2. Low Contrast Performance The low contrast performance of the fluoroscopic system shall resolve a minimum hole size of 3 mm using a test tool composed of a 1.0 mm aluminum sheet with two sets of four holes of dimension 1.0, 3.0, 5.0 and 7.0 mm and 1 inches of Type 1100 aluminum or an equivalent device.
          X-ray Tube Voltage
          Designed Operating
          Range          		 kVp
          Measured          		 Al (mm)
          Below 50 30 0.3
          40 0.4
          49 0.5
          50-70 50 1.2
          60 1.3
          70 1.5
          Above 70 71 2.1
          80 2.3
          90 2.5
          100 2.7
          110 3.0
          120 3.2
          130 3.5
          140 3.8
          150 4.1
          Operative kVp Minimum Total Filtration
          (Inherent Plus Added)
          Below 50 0.5 mm Al
          50-70 1.5 mm Al
          Above 70 2.5 mm Al
          1. Certified equipment shall indicate with a signal audible to the operator the termination of a pre-set time interval, not to exceed five (5) minutes. When engaged, the signal must continue until the reset button is depressed. For uncertified equipment the passage of a preset time, not to exceed five (5) minutes, must be noted by a signal audible to the operator or an interruption of the fluoroscopic beam.
          1. Exposure rate limits for certified fluoroscopic equipment manufactured before May 19, 1995:
            • Automatic Mode: 10 R/minute
            • Manual Mode: 5 R/minute
            • High Level Control (HLC) Mode: 5 R/minute (when not operating in HLC)
            • HLC Mode: 20 R/minute (when operating in HLC and not recording the image)
          2. Certified fluoroscopic equipment manufactured after May 19, 1995 and capable of producing a radiation exposure rate in excess of 5 R/min must have automatic exposure rate control. Such equipment is limited to maximum exposure rate of 10 R/minute.
          3. Certified fluoroscopic equipment manufactured after May 19, 1995 and having HLC must meet requirement (2). Such units are limited to 20 R/min when operating in HLC and not recording the image in a pulsed mode.
          4. Uncertified fluoroscopic equipment is limited to a maximum exposure rate of 10 R/min.
          5. The fluoroscopic exposure rate in automatic and/or manual mode must not exceed 5 R/min when measured with a patient equivalent phantom composed of 1 inches of Type 1100 aluminum and 0.5 mm of copper or an equivalent device.

          Bibliography

          1. Analysis of Retakes: Understanding, Managing and Using an Analysis of Retakes Program for Quality Assurance. FDA 79-8097.
          2. Acceptance Testing of Radiological Imaging Equipment. Edited by Pei-Jan Paul Lin, AAPM-ACR-SRE, 1982.
          3. A Basic Quality Assurance Program for Small Diagnostic Radiology Facilities. FDA 83-8210.
          4. Calculation of Patient Skin Dose from Diagnostic X-ray Procedures. I.R. Edmons, British Journal of Radiology, 57 733-734 (1984).
          5. Checklist for Establishing a Diagnostic Radiology Quality Assurance Program. FDA 83-8219.
          6. Quality Control in Diagnostic Radiology. American Association of Physicists in Medicine, Report 74, July 2002.
          7. The Effect of Decreased Developer Activity on Patient Exposure. C.B. Burns, Radiologic Technology, 54, 391-393 (1983).
          8. Evaluation of Cassette Performance. R.A. Schmidt, Radiology, 146: 801-806 (March 1983).
          9. Medical Radiation Exposure of Pregnant and Potentially Pregnant Women, National Council on Radiation Protection and Measurements, (NCRP) No. 54 (1977).
          10. National Conference of Referral Criteria for X-ray Examinations. FDA 79-8083.
          11. Patient Radiation Exposure in Diagnostic Radiology Examinations: An Overview. FDA 79-8217.
          12. Performance Specifications for Diagnostic X-ray Exposure. W.R. Hendee, et.al., Radiology 120: 409-412 (August 1976).
          13. Photographic Quality Assurance in Diagnostic Radiology, Nuclear Medicine and Radiation Therapy, Volume 1: The Basic Principles of Daily Photographic Quality Assurance. FDA 76-8043.
          14. Photographic Quality Assurance in Diagnostic Radiology, Nuclear Medicine and Radiation Therapy, Volume 2: Photographic Processing Quality Assurance and the Evaluation of Photographic Materials. FDA 77-8018.
          15. Physics of Medical Imaging. Edited by A. Haus, AAPM (1979).
          16. Quality Control in Diagnostic Imaging. Gary, Winkler, Stears, and Frank. Aspen Publishers, Rockville, MD (1983).
          17. Quality Assurance for Diagnostic Imaging Equipment. National Council on Radiation Protection and Measurements (NCRP), No. 99 (1988).
          18. Quality Assurance in Diagnostic Radiology. J. McLemore, Yearbook Medical (1979).
          19. Radiation Protection for Medical and Allied Health Personnel, (NCRP), No. 48 (1976).
          20. Radiographic Film Processing Quality Assurance: A Self-Teaching Workbook. FDA 81-8146.
          21. Radiographic Latent Image Processing. W.E.J. McKinney, ASNT Section 7, NDT Handbook (1982).
          22. Radiologic Science for Technologist. S.C. Bushong, Mosby Company (1984).
          23. Regulations for the Administration and Enforcement of the Radiation Control for Health and Safety Act of 1968. USDHHS, April 2003.
          24. Review of NCRP Radiation Dose Limit for Embryo and Fetus in Occupationally Exposed Women, (NCRP) No. 53 (1977).
          25. Title 10 NY Code of Rules and Regulations, Chapter 1, Part 16 "Ionizing Radiation", February 2004.
          26. The Basics of Film Processing in Medical Imaging - Haus and Jaskulski. Medical Physics Publishing, Madison, WI (1997).

          List of Appendices

          • Quality Control Test Frequency
          • Processor Problem Troubleshooting

          Appendix C - Sample Test Procedures

          • C-1 Light Field/X-ray Field alignment
          • C-2 PBL
          • C-3 X-ray Field/Image Receptor alignmentM
          • Repeat-Reject Analysis
          • Performance Specifications

          Appendix F - Policy and Procedures

          • F-1 Policy and Procedures for Patient Holding
          • F-2 Policy and Procedures for Pregnant Workers
          • F-3 Policy and Procedures of Use of Gonad Shielding
          • F-4 Policy and Procedures for Shielding Scoliosis Patients
          • F-5 Policy and Procedures for Pregnant Patients
          • F-6 Policy and Procedures for Personnel Monitoring
          • Radiation Output Measurements