Effective Date: 01/08/1997
Title: Section 16.122 - Teletherapy
16.122 Teletherapy. The regulations and provisions of this section govern the use of teletherapy units containing sealed radioactive sources for medical purposes.
(a) Maintenance:
(1) Each teletherapy unit shall be routinely maintained in accordance with the manufacturer's recommendations, including those for periodic replacement of components.
(2) Each teletherapy unit shall be fully inspected and serviced during source replacement or at intervals not to exceed five years, whichever comes first.
(3) Any repairs found to be necessary during maintenance, service or inspection shall be promptly made.
(4) Maintenance and service of teletherapy units performed pursuant to paragraph (2) of this subdivision, as well as any service that could compromise the safety of the unit, shall be performed only by persons specifically licensed by the U.S. Nuclear Regulatory Commission or by an agreement state to do so. This includes but is not limited to: installing, relocating or removing a teletherapy sealed source or a teletherapy unit that contains a sealed source; maintenance, adjustment or repair of the source drawer, shutter or other mechanism that could expose the source, reduce the shielding around the source or result in increased radiation levels.
(5) Records of maintenance and service performed pursuant to paragraph (2) of this subdivision shall be retained for the duration of the license. The records shall include the name of the person performing the service, his/her license number, the date of the service, a list of components inspected, the findings of the inspection, a list of components serviced or replaced and the signature of the licensed individual performing the service.
(b) Safety Instruction.
(1) A licensee shall post instructions at the teletherapy unit console. These instructions must inform the operator of:
(i) The procedure to be followed to ensure that only the patient is in the treatment room before turning the primary beam of radiation on to begin a treatment or after a door interlock interruption:
(ii) The procedure to be followed if:
(a) The operator is unable to turn the primary beam of radiation off with controls outside the treatment room or if any other abnormal operation occurs; and
(b) The names and telephone numbers of the authorized users and Radiation Safety Officer to be immediately contacted if the teletherapy unit or console operates abnormally.
(2) A licensee shall provide instruction in the topics identified in paragraph (1) of this subdivision to all individuals who will operate a teletherapy unit before such operation is permitted and annually thereafter. This instruction shall include "dry runs" of emergency procedures.
(3) A licensee shall retain for three years a record of individuals receiving instruction required by paragraph (2) of this subdivision, a description of the instruction, the date of instruction, and the name of the individual who gave the instruction.
(c) Safety Precautions:
(1) A licensee shall control access to the teletherapy room by a door at each entrance.
(2) A licensee shall equip each entrance to the teletherapy room with an electrical interlock system that will:
(i) Prevent the operator from turning the primary beam of radiation on unless each treatment room entrance door is closed;
(ii) Turn the primary beam of radiation off immediately when an entrance door is opened; and
(iii) Prevent the primary beam of radiation from being turned on following an interlock interruption until all treatment room entrance doors are closed and the beam on-off control is reset at the console.
(3) A licensee shall equip each entrance to the teletherapy room with a beam condition indicator light.
(4) A licensee shall install in each teletherapy room a permanent radiation monitor capable of continuously monitoring beam status.
(i) The radiation monitor must provide visible notice of a teletherapy unit malfunction that results in an exposed or partially exposed source, and must be observable by an individual entering the teletherapy room.
(ii) The radiation monitor must be equipped with a backup power supply separate from the power supply to the teletherapy unit. This backup power supply may be a battery system.
(iii) The radiation monitor must be checked for proper operation each day before the teletherapy unit is used for treatment of patients.
(iv) A licensee shall maintain a record of the check required by subparagraph (iii) of this paragraph for three years.
(v) If a radiation monitor is inoperable, the licensee shall require any individual entering the teletherapy room to use a survey instrument or audible alarm personal dosimeter to monitor for any malfunction of the source exposure mechanism that may result in an exposed or partially exposed source. The instrument or dosimeter must be checked for proper operation at the beginning of each day of use. The licensee shall keep a record as described in subparagraph (iv) of this paragraph. (vi) A licensee shall promptly repair or replace the radiation monitor if it is inoperable.
(5) A licensee shall construct or equip each teletherapy room to permit continuous observation of the patient from the teletherapy unit console during irradiation and to permit communication with the patient.
(6) A licensee shall ensure that either a physician named on the radioactive material license, or a licensed radiotherapy technologist shall observe the patient continuously during each treatment.
(7) A licensee shall ensure that a quality assurance program is conducted under the supervision of a physician or radiation therapy physicist named on the license. The program must be designed to ensure consistent and safe fulfillment of the dose prescription to the target volume, with minimal dose to normal tissue and minimal exposure to personnel.
(d) Dosimetry Equipment:
(1) A licensee shall have a calibrated dosimetry system available for use. To satisfy this requirement, one of the following two conditions must be met.
(i) The system must have been calibrated by the National Institute of Standards and Technology or by a calibration laboratory accredited by the American Association of Physicists in Medicine. The calibration must have been performed within the previous two years and after any servicing that may have affected system calibration; or
(ii) The system must have been calibrated within the previous four years; eighteen to thirty months after that calibration, the system must have been intercompared at an intercomparison meeting with another dosimetry system that was calibrated within the past twenty-four months by the National Institute of Standards and Technology or by a calibration laboratory accredited by the American Association of Physicists in Medicine. The intercomparison meeting must be sanctioned by a calibration laboratory or radiologic physics center accredited by the American Association of Physicists in Medicine. The results of the intercomparison meeting must have indicated that the calibration factor of the licensee's system had not changed by more than 2 percent. The licensee may not use the intercomparison result to change the calibration factor.
(2) The licensee shall have available for use a dosimetry system for spot-check measurements. To satisfy this requirement, the system may be compared with a system that has been calibrated in accordance with paragraph (1) of this subdivision. This comparison must have been performed within the previous year and after each servicing that may have affected system calibration. Alternatively, the spot-check system may be the same system used to meet the requirement in paragraph (1) of this subdivision.
(3) The licensee shall retain a record of each calibration, intercomparison, and comparison for the duration of the license. For each calibration, intercomparison, or comparison, the record must include the date, the model numbers and serial numbers of the instruments that were calibrated, intercompared, or compared as required by paragraphs (1) and (2) of this subdivision, the correction factor that was determined from the calibration or comparison or the apparent correction factor that was determined from an intercomparison, the names of the individuals who performed the calibration, intercomparison, or comparison, and evidence that the intercomparison meeting was sanctioned by a calibration laboratory or radiologic physics center accredited by American Association of Physicists in Medicine.
(e) Full calibration measurements:
(1) A licensee authorized to use a teletherapy unit for medical use shall perform full calibration measurements of each teletherapy unit:
(i) Before the first medical use of the unit; and
(ii) Before medical use under the following conditions:
(a) Whenever spot-check measurements indicate that the output differs by more than 5 percent from the output obtained at the last full calibration corrected mathematically for radioactive decay;
(b) Following replacement of the source or following reinstallation of the teletherapy unit in a new location;
(c) Following any repair of the teletherapy unit that includes removal of the source or major repair of the components associated with the source exposure assembly; and
(iii) At intervals not exceeding one year.
(2) To satisfy the requirement of paragraph (1) of this subdivision, full calibration measurements must include determination of:
(i) The output within +/- 3 percent for the range of field sizes and for the distance or range of distances used for medical use; measurements shall be made with the dosimetry system described in paragraph (1) of subdivision (d) of this section; (ii) The coincidence of the radiation field and the field indicated by the light beam localizing device;
(iii) The uniformity of the radiation field and its dependence on the orientation of the useful beam;
(iv) Timer constancy, accuracy and linearity over the range of use;
(v) On-off error; and
(vi) The accuracy of all distance measuring and localization devices in medical use.
(3) A licensee shall make full calibration measurements required by paragraph (1) of this subdivision in accordance with procedures described in 10CFR35.632 (See section 16.200 of this Part).
(4) A licensee shall correct mathematically the outputs determined in subparagraph (i) of paragraph (2) of this subdivision for physical decay for intervals not exceeding one month for Cobalt-60.
(5) Full calibration measurements required by paragraph (1) of this subdivision and physical decay corrections required by paragraph (4) of this subdivision must be performed by the radiation therapy physicist named on the license.
(6) A licensee shall retain a record of each calibration for the duration of use of the teletherapy unit source plus 6 years. The record must include the date of the calibration, the manufacturer's name, model number, and serial number for both the teletherapy unit and the source, the model numbers and serial numbers of the instruments used to calibrate the teletherapy unit, tables that describe the output of the unit over the range of field sizes and for the range of distances used in radiation therapy, a determination of the coincidence of the radiation field and the field indicated by the light beam localizing device, an assessment of timer linearity and constancy, the calculated on-off error, the estimated accuracy of each distance measuring or localization device, and the signature of the radiation therapy physicist who performed the calibration.
(f) Radiation Therapy Physicist:
(1) The licensee shall ensure that any individual who performs the duties of a radiation therapy physicist in a teletherapy facility meets the criteria in subparagraphs (i), (ii) or (iii), of this paragraph, except that as of January 1, 2000 only individuals who are certified as described in subparagraph (i) shall perform such duties.
(i) The individual is certified by the American Board of Radiology or the American Board of Medical Physics in a branch of medical physics which deals with the therapeutic application of roentgen rays, gamma rays, electrons or other charged particle beams, neutrons, and radiation from sealed radionuclide sources, and the equipment associated with the production and use of these radiations; or
(ii)(a) The individual holds a baccalaureate degree, a master's degree or a doctorate in radiological physics or a closely related field such as physics, biophysics or health physics, and has completed one year of full-time training in therapeutic radiological physics and an additional year of full-time work experience under the supervision of a radiation therapy physicist at a medical institution that includes the tasks listed in subdivisions (e),(g),(h),and (i) of this section; and
(b) The individual's qualifications, including documentation of the training and experience described in clause (a) of this subparagraph and a written endorsement of the technical qualifications of the individual by a physicist who is certified as described in subparagraph (i) of this paragraph and who has personal knowledge of the individual's performance of the tasks listed in subdivisions (e),(g),(h) and (i) of this section have been submitted to the department for evaluation and approved; or
(iii) The individual is named as a radiation therapy physicist on a current teletherapy license issued by the department.
(g) Periodic spot-checks:
(1) A licensee authorized to use teletherapy units for medical use shall perform output spot-checks on each teletherapy unit once in each calendar month that include determination of:
(i) Timer constancy, and timer linearity over the range of use;
(ii) On-off error;
(iii) The coincidence of the radiation field and the field indicated by the light beam localizing device;
(iv) The accuracy of all distance-measuring and localization devices used for medical use;
(v) The output for one typical set of operating conditions measured with the dosimetry system described in paragraph (2) of subdivision (d) of this section and
(vi) The difference between the measurement made in subparagraph (v) of paragraph (1) of this subdivision and the anticipated output, expressed as a percentage of the anticipated output (i.e., the value obtained at last full calibration corrected mathematically for physical decay). (2) A licensee shall perform measurements required by paragraph (1) of this subdivision in accordance with procedures establis hed by the radiation therapy physicist. That individual need not actually perform the spot-check measurements.
(3) A licensee shall have the radiation therapy physicist review the results of each spot-check within 15 days. The physicist shall promptly notify the licensee in writing of the results of each spot-check. The licensee shall keep a copy of each written notification for three years.
(4) A licensee authorized to use a teletherapy unit for medical use shall perform safety spot-checks of each teletherapy facility once in each calendar month that assure proper operation of:
(i) Electrical interlocks at each teletherapy room entrance;
(ii) Electrical or mechanical stops installed for the purpose of limiting use of the primary beam of radiation (restriction of source housing angulation or elevation, carriage or stand travel and operation of the beam on-off mechanism);
(iii) Beam condition indicator lights on the teletherapy unit, on the control console, and in the facility;
(iv) Viewing systems;
(v) Treatment room doors from inside and outside the treatment room; and
(vi) Electrically assisted treatment room doors with the teletherapy unit electrical power turned off.
(5) A licensee shall arrange for prompt repair of any system identified in paragraph (4) of this subdivision that is not operating properly, and shall not use the teletherapy unit following door interlock malfunction until the interlock system has been repaired.
(6) A licensee shall retain a record of each spot-check required by paragraphs (1) and (4) of this subdivision for three years. The record must include the date of the spot-check, the manufacturer's name, model number, and serial number for both the teletherapy unit and source, the
manufacturer's name, model number and serial number of the instrument used to measure the output of the teletherapy unit, an assessment of timer linearity and constancy, the calculated on-off error, a determination of the coincidence of the radiation field and the field indicated by the light beam localizing device, the determined accuracy of each distance measuring or localization device, the difference between the anticipated output and the measured output, notations indicating the operability of each entrance door electrical interlock, each electrical or mechanical stop, each beam condition indicator light, the viewing system and doors, and the signature of the individual who performed the periodic spot-check.
(h) Safety checks for teletherapy facilities:
(1) A licensee shall promptly check all systems listed in paragraph (4) of subdivision (g) of this section for proper function after each installation of a teletherapy source and after any change in treatment room shielding, any change in the location of the teletherapy unit within the treatment room or relocation of the teletherapy unit to another room.
(2) If the results of the checks required in paragraph (1) of this subdivision indicate the malfunction of any system specified in paragraph (4) of subdivision (g) of this section, the licensee shall lock the control console in the off position and not use the unit except as may be necessary to repair, replace, or check the malfunctioning system.
(3) A licensee shall retain for three years a record of the facility checks following installation of a source. The record must include notations indicating the operability of each entrance door interlock, each electrical or mechanical stop, each beam condition indicator light, the viewing system, and doors, and the signature of the Radiation Safety Officer.
(i) Radiation surveys for teletherapy facilities:
(1) Before medical use and after making any change for which safety checks are required pursuant to paragraph (1) of subdivision (h) of this section, the licensee shall perform radiation surveys to verify that:
(i) The maximum and average dose rates at one meter from the teletherapy source with the source in the off position and the collimators set for a normal treatment field do not exceed 10 millirem per hour and 2 millirem per hour, respectively; and
(ii) With the teletherapy source in the "on" position with the largest clinically available treatment field and with a scattering phantom in the primary beam of radiation, that:
(a) Radiation dose quantities per unit time in restricted areas are not likely to cause personnel exposures in excess of the limits specified in section 16.6 of this Part; and
(b) Radiation dose quantities per unit time in unrestricted areas do not exceed the limits specified in section 16.7 of this Part.
(2) If the results of the surveys required in paragraph (1) of this subdivision indicate any radiation dose quantity per unit time in excess of the respective limit specified in that paragraph, the licensee shall lock the control in the off position and not use the unit: (i) Except as may be necessary to repair, replace, or test the teletherapy unit shielding or the treatment room shielding;
(3) A licensee shall retain a record of the radiation measurements made following installation of a source for the duration of the license. The record must include the date of the measurements, the reason the survey is required, the manufacturer's name, model number and serial number of the teletherapy unit, the source, and the instrument used to measure radiation levels, each dose rate measured around the teletherapy source while in the "off" position and the average of all measurements, a plan of the areas surrounding the treatment room that were surveyed, the measured dose rate at the point of maximum exposure in each area expressed in millirem per hour, the calculated maximum quantity of radiation over a period of one week for each restricted and unrestricted area, and the signature of the radiation safety officer.
(j) Reports. A licensee shall report to the department by telephone within 24 hours any malfunction of the source exposure assembly. This notification must be followed within thirty days by a written report describing the cause of the malfunction and corrective steps taken by the licensee. The report must also describe any radiation exposure to individuals that occurred as a result of the malfunction.
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