Section 11-45-238 - Therapeutic radiation machines - photon therapy systems (five hundred kilovolts and above) and electron therapy systems (five hundred kilo electron volts and above)(a) Each facility location authorized to use a therapeutic radiation machine in accordance with this section shall possess appropriately calibrated portable monitoring equipment. As a minimum, such equipment shall include a portable radiation measurement survey instrument capable of measuring dose rates over the range one millirem (ten microsieverts) per hour to one thousand millirems (ten millisieverts) per hour. The survey instrument(s) shall be operable and calibrated in accordance with section 11-45-240.(b) Leakage radiation outside the maximum useful beam in photon and electron modes: (1) The absorbed dose rate due to leakage radiation (excluding neutrons) at any point outside the maximum sized useful beam, but within a circular plane of radius two meters which is perpendicular to and centered on the central axis of the useful beam at the nominal treatment distance (i.e. patient plane), shall not exceed a maximum of 0.2 percent and an average of 0.1 percent of the absorbed dose rate on the central axis of the beam at the nominal treatment distance. Measurements shall be averaged over an area not exceeding one hundred square centimeters at a minimum of sixteen points uniformly distributed in the plane;(2) Except for the area defined in paragraph (1), the absorbed dose rate in water (excluding that from neutrons) at one meter from the electron path between the source and the target or electron window shall not exceed 0.5 percent of the absorbed dose rate in water on the central axis of the beam at the nominal treatment distance. Measurements shall be averaged over an area not exceeding one hundred square centimeters at a minimum of sixteen points uniformly distributed in the plane;(3) The neutron absorbed dose rate outside the useful beam shall be kept as low as practicable. Measurements of the portion of the leakage radiation dose contributed by neutrons shall be averaged over an area not exceeding eight hundred square centimeters; and(4) For each therapeutic radiation machine, the licensee shall determine, or obtain from the manufacturer, the leakage radiation existing at the positions specified in paragraphs (1) through (3) for the specified operating conditions. Records on leakage radiation measurements shall be maintained at the installation for inspection.(c) Leakage radiation through beam limiting devices: (1) Photon radiation: All adjustable or interchangeable beam limiting devices shall attenuate the useful beam such that at the nominal treatment distance, the maximum absorbed dose anywhere in the area shielded by the beam limiting device(s) shall not exceed two percent of the maximum absorbed dose on the central axis of the useful beam measured in a ten centimeters by ten centimeters radiation field;(2) Electron radiation: All adjustable or interchangeable electron applicators shall attenuate the radiation, including but not limited to photon radiation generated by electrons incident on the beam limiting device and electron applicator and other parts of the radiation head, such that the absorbed dose in a plane perpendicular to the central axis of the useful beam at the nominal treatment distance shall not exceed: (A) A maximum of two percent of the absorbed dose on the central axis of the useful beam at the nominal treatment distance. This limit shall apply beyond a line seven centimeters outside the periphery of the useful beam; and(B) A maximum of ten percent of the absorbed dose on the central axis of the useful beam at the nominal treatment distance. This limit shall apply beyond a line two centimeters outside the periphery of the useful beam.(3) Measurement of leakage radiation: (A) Photon radiation: Measurements of leakage radiation through the beam limiting devices shall be made with the beam limiting devices closed and any residual aperture blocked by at least two tenth value layers of suitable absorbing material. In the case of overlapping beam limiting devices, the leakage radiation through each set shall be measured independently at the depth of maximum dose. Measurements shall be made using a radiation detector of area not exceeding ten square centimeters;(B) Electron radiation: Measurements of leakage radiation through the electron applicators shall be made with the electron beam directed into the air and using a radiation detector of area up to but not exceeding one square centimeter suitably protected against radiation which has been scattered from material beyond the radiation detector. Measurements shall be made using one centimeter of water equivalent build up material.(4) When adjustable beam limiting devices are used, the position and shape of the radiation field shall be indicated by a light field.(d) Filters/wedges: (1) Each filter and/or wedge which is removable from the system shall be clearly marked with an identification number. For removable wedge filters, the nominal wedge angle shall appear on the wedge or wedge tray (if permanently mounted to the tray). If the wedge or wedge tray is damaged, the wedge transmission factor shall be redetermined;(2) If the absorbed dose rate information required by subsection (a) relates exclusively to operation with a field flattening or beam scattering filter in place, such filter shall be removable only by the use of tools;(3) For equipment manufactured after the effective date of this chapter which utilize a system of wedge filters, interchangeable field flattening filters, or interchangeable beam scattering foils: (A) Irradiation shall not be possible until a selection of a filter or a positive selection to use "no filter" has been made at the treatment control panel, either manually or automatically;(B) An interlock system shall be provided to prevent irradiation if the filter selected is not in the correct position;(C) A display shall be provided at the treatment control panel showing the wedge filter(s), interchangeable field flattening filter(s), and/or interchangeable beam scattering foil(s) in use; and(D) An interlock shall be provided to prevent irradiation if any filter and/or beam scattering foil selection operation carried out in the treatment room does not agree with the filter and/or beam scattering foil selection operation carried out at the treatment control panel.(e) For equipment manufactured after the effective date of this chapter, the licensee shall determine during acceptance testing, or obtain from the manufacturer, data sufficient to ensure that x-ray stray radiation in the useful electron beam, absorbed dose at the surface during x-ray irradiation and stray neutron radiation in the useful x-ray beam are in compliance with International Electrotechnical Commission (IEC) Document 601-2-1.(f) All therapeutic radiation machines subject to this section shall be provided with beam monitoring devices. The sensors for this device shall be fixed in the useful beam during treatment to indicate the air kerma rate or dose rate. (1) Equipment manufactured after the effective date of this chapter shall be provided with at least two independently powered integrating dose meters. Alternatively, a common power supply may be used if the production of radiation is terminated upon failure of any common element.(2) Equipment manufactured on or before the effective date of this chapter shall be provided with at least one radiation detector. This detector shall be incorporated into a useful beam monitoring system;(3) The detector and the system into which that detector is incorporated shall meet the following requirements: (A) Each detector shall be removable only with tools and, if movable, shall be interlocked to prevent incorrect positioning;(B) Each detector shall form part of a beam monitoring system from which readings in dose monitor units the absorbed dose at a reference point in the treatment volume can be calculated;(C) Each beam monitoring system shall be capable of independently monitoring, interrupting, and terminating irradiation; and(D) For equipment manufactured after the effective date of this chapter, the design of the beam monitoring systems shall ensure that the: (i) Malfunctioning of one system shall not affect the correct functioning of the secondary system; and(ii) Failure of any element common to both systems which could affect the correct function of both systems shall terminate irradiation or prevent the initiation of radiation.(E) Each beam monitoring system shall have a legible display at the treatment control panel. For equipment manufactured after the effective date of this chapter, each display shall: (i) Maintain a reading until intentionally reset;(ii) Have only one scale and no electrical or mechanical scale multiplying factors;(iii) Utilize a design such that increasing dose is displayed by increasing numbers; and(iv) In the event of power failure, the beam monitoring information required in clause (iii) displayed at the control panel at the time of failure shall be retrievable in at least one system for a twenty minute period of time.(g) Beam symmetry: (1) Bent-beam linear accelerators subject to this section shall be provided with auxiliary device(s) to monitor beam symmetry;(2) The device(s) referenced in paragraph (1) shall be able to detect field asymmetry greater than ten percent; and(3) The device(s) referenced in paragraph (1) shall be configured to terminate irradiation if the specifications in paragraph (2) cannot be maintained.(h) Selection and display of dose monitor units: (1) Irradiation shall not be possible until a selection of a number of dose monitor units has been made at the treatment control panel;(2) The pre-selected number of dose monitor units shall be displayed at the treatment control panel until reset manually for the next irradiation;(3) After termination of irradiation, it shall be necessary to reset the dosimeter display before subsequent treatment can be initiated; and(4) For equipment manufactured after the effective date of this chapter, after termination of irradiation, it shall be necessary for the operator to reset the pre-selected dose monitor units before irradiation can be initiated.(i) For equipment manufactured after the effective date of this chapter, a system shall be provided from which readings the air kerma rate or absorbed dose rate at a reference point in the treatment volume can be calculated. The radiation detectors specified in subsection (f) may form part of this system. In addition: (1) The dose monitor unit dose rate shall be displayed at the treatment control panel;(2) If the equipment can deliver under any conditions an air kerma rate or absorbed dose rate at the nominal treatment distance more than twice the maximum value specified by the manufacturer, a device shall be provided which terminates irradiation when the air kerma rate or absorbed dose rate exceeds a value twice the specified maximum. The dose rate at which the irradiation shall be terminated shall be a record maintained by the licensee;(3) For equipment manufactured after the effective date of this chapter, if the equipment can deliver under any conditions an air kerma rate or absorbed dose rate at the nominal treatment distance more than ten times the maximum value specified by the manufacturer, a device shall be provided to prevent the air kerma rate or absorbed dose rate anywhere in the radiation field from exceeding twice the specified maximum value and to terminate irradiation if the excess absorbed dose at the nominal treatment distance exceeds four hundred rads (four grays); and(4) For each therapeutic radiation machine, the licensee shall determine, or obtain from the manufacturer, the maximum value(s) specified in paragraphs (2) and (3) for the specified operating conditions. Records of these maximum value(s) shall be maintained at the installation for inspection.(j) Termination of irradiation by the beam monitoring system or systems during stationary beam radiation therapy: (1) Each primary system shall terminate irradiation when the pre-selected number of dose monitor units has been detected by the system;(2) If the original design of the equipment included a secondary dose monitoring system, that system shall be capable of terminating irradiation when not more than fifteen percent or forty dose monitor units above the pre-selected number of dose monitor units set at the control panel has been detected by the secondary dose monitoring system; and(3) For equipment manufactured after the effective date of this chapter, an indicator on the control panel shall show which monitoring system has terminated irradiation.(k) It shall be possible to terminate irradiation and equipment movement or go from an interruption condition to termination condition at any time from the operator's position at the treatment control panel.(l) If a therapeutic radiation machine has an interrupt mode, it shall be possible to interrupt irradiation and equipment movements at any time from the treatment control panel. Following an interruption it shall be possible to restart irradiation by operator action without any reselection of operating conditions. If any change is made of a pre-selected value during an interruption, irradiation and equipment movements shall be automatically terminated.(m) A suitable irradiation control device shall be provided to terminate the irradiation after a pre-set time interval. (1) A timer shall be provided which has a display at the treatment control panel. The timer shall have a preset time selector and an elapsed time indicator;(2) The timer shall be a cumulative timer which activates with an indication of "BEAM-ON" and retains its reading after irradiation is interrupted or terminated. After irradiation is terminated and before irradiation can be reinitiated, it shall be necessary to reset the elapsed time indicator;(3) For equipment manufactured after the effective date of this chapter, after termination of irradiation and before irradiation can be reinitiated, it shall be necessary for the operator to reset the pre-set time selector;(4) The timer shall terminate irradiation when a pre-selected time has elapsed, if the dose monitoring systems have not previously terminated irradiation.(n) Equipment capable of both x-ray therapy and electron therapy shall meet the following additional requirements: (1) Irradiation shall not be possible until a selection of radiation type (x-rays or electrons) has been made at the treatment control panel;(2) The radiation type selected shall be displayed at the treatment control panel before and during irradiation;(3) An interlock system shall be provided to ensure that the equipment can principally emit only the radiation type which has been selected;(4) An interlock system shall be provided to prevent irradiation with x-rays, except to obtain a verification film, when electron applicators are fitted;(5) An interlock system shall be provided to prevent irradiation with electrons when accessories specific for x-ray therapy are fitted; and(6) An interlock system shall be provided to prevent irradiation if any selected operations carried out in the treatment room do not agree with the selected operations carried out at the treatment control panel.(o) Equipment capable of generating radiation beams of different energies shall meet the following requirements: (1) Irradiation shall not be possible until a selection of energy has been made at the treatment control panel;(2) The measured energy value selected shall be displayed (megavolts for photons and mega electron volts for electrons) at the treatment control panel before and during irradiation; and(3) Irradiation shall not be possible until the appropriate flattening filter or scattering foil for the selected energy is in its proper location.(p) Therapeutic radiation machines capable of both stationary beam radiation therapy and rotational arc radiation therapy shall meet the following requirements: (1) Irradiation shall not be possible until a selection of stationary beam radiation therapy or rotational arc radiation therapy has been made at the treatment control panel;(2) The mode of operation shall be displayed at the treatment control panel;(3) An interlock system shall be provided to ensure that the equipment can operate only in the mode which has been selected;(4) An interlock system shall be provided to prevent irradiation if any selected parameter in the treatment room does not agree with the selected parameter at the treatment control panel;(5) Rotational arc radiation therapy shall be controlled to obtain the selected relationships between incremental dose monitor units and incremental angle of movement for equipment manufactured after the effective date of this chapter: (A) An interlock system shall be provided to terminate irradiation if the number of dose monitor units delivered in any fifteen degrees of arc differs by more than twenty percent from the selected value;(B) Where gantry angle terminates the irradiation in rotational arc radiation therapy, the dose monitor units shall differ by less than five percent from the value calculated from the absorbed dose per unit angle and total angle relationship;(C) An interlock shall be provided to prevent the gantry moving more than five degrees beyond the selected angular limits during rotational arc radiation therapy;(D) An interlock shall be provided to require that a selection of direction be made at the treatment control panel in all units which are capable of both clockwise and counter-clockwise rotational arc radiation therapy.(6) Where the beam monitor system terminates the irradiation in rotational arc radiation therapy, the termination of irradiation shall be as required by subsection (j); and(7) For equipment manufactured after the effective date of this chapter, an interlock system shall be provided to terminate irradiation if movement of the gantry: (A) Occurs during stationary beam radiation therapy; or(B) Stops during rotational arc radiation therapy unless such stoppage is a pre-planned function.(q) Facility design requirements for therapeutic radiation machines operating above five hundred kilovolts: In addition to shielding adequate to meet requirements of section 11-45-241, the following design requirements are made: (1) All protective barriers shall be fixed, except for access doors to the treatment room or movable beam interceptors;(2) In addition to other requirements specified in this subchapter, the control panel shall also: (A) Be located outside the treatment room;(B) Provide an indication of whether electrical power is available at the control panel and if activation of the radiation is possible;(C) Provide an indication of whether radiation is being produced; and(D) Include an access control (locking) device which shall prevent unauthorized use of the therapeutic radiation machine;(3) Windows, mirrors, closed-circuit television or an equivalent viewing system shall be provided to permit continuous observation of the patient following positioning and during irradiation and shall be so located that the operator may observe the patient from the treatment control panel. The therapeutic radiation machine shall not be used for patient irradiation unless at least one viewing system is operational;(4) Provision shall be made for continuous two-way aural communication between the patient and the operator at the control panel. The therapeutic radiation machine shall not be used for irradiation of patients unless continuous two-way aural communication is possible;(5) Treatment room entrances shall be provided with warning lights in a readily observable position near the outside of all access doors, which shall indicate when the useful beam is "ON" and when it is "OFF";(6) Interlocks shall be provided such that all entrance doors shall be closed before treatment can be initiated or continued. If the radiation beam is interrupted by any door opening, it shall not be possible to restore the machine to operation without closing the door and reinitiating irradiation by manual action at the control panel;(7) If the shielding material in any protective barrier requires the presence of a beam interceptor to ensure compliance with subchapter 4, interlocks shall be provided to prevent the production of radiation, unless the beam interceptor is in place, whenever the useful beam is directed at the designated barrier(s);(8) At least one "scram button" or other emergency power cutoff switch shall be located in the radiation therapy room and shall terminate all equipment electrical power including radiation and mechanical motion. This switch is in addition to the termination switch required by subsection (k). All emergency power cutoff switches shall include a manual reset so that the therapeutic radiation machine cannot be restarted from the unit's control console without resetting the emergency cutoff switch;(9) All safety interlocks shall be designed so that any defect or component failure in the safety interlock system prevents or terminates operation of the therapeutic radiation machine; and(10) Surveys for residual activity shall be conducted on all therapeutic radiation machines capable of generating photon and electron energies above ten megavolts before machining, removing, or working on therapeutic radiation machine components which may have become activated due to photo-neutron production.(r) Qualified medical physicist support: (1) The services of a qualified medical physicist shall be utilized in facilities having therapeutic radiation machines with energies of five hundred kilovolts and above. The qualified medical physicist shall be responsible for: (A) Full calibration(s) required by subsection (t) and protection surveys required by section 11-45-234(a);(B) Supervision and review of dosimetry;(C) Beam data acquisition and transfer for computerized dosimetry, and supervision of its use;(D) Quality assurance, including quality assurance check review required by subsections (u) and (v);(E) Consultation with the authorized user in treatment planning, as needed; and(F) Perform calculations/assessments regarding misadministrations.(2) If the qualified medical physicist is not a full-time employee of the licensee, the operating procedures required by subsection (s) shall also specifically address how the qualified medical physicist is to be contacted for problems or emergencies, as well as the specific actions, if any, to be taken until the qualified medical physicist can be contacted.(s) Operating procedures: (1) No individual, other than the patient, shall be in the treatment room during treatment or during any irradiation for testing or calibration purposes;(2) Therapeutic radiation machines shall not be made available for medical use unless the requirements of section 11-45-234(a), subsections (t) and (u) have been met;(3) Therapeutic radiation machines, when not in operation, shall be secured to prevent unauthorized use;(4) If a patient must be held in position during treatment, mechanical supporting or restraining devices shall be used; and(5) A copy of the current operating and emergency procedures shall be maintained at the therapeutic radiation machine control console.(t) Full calibration measurements: (1) Full calibration of a therapeutic radiation machine subject to this section shall be performed by, or under the direct supervision of, a qualified medical physicist: (A) Before the first medical use following installation or reinstallation of the therapeutic radiation machine;(B) At intervals not exceeding one year; and(C) Before medical use under the following conditions: (i) Whenever quality assurance check measurements indicate that the radiation output differs by more than five percent from the value obtained at the last full calibration and the difference cannot be easily discerned; and(ii) Following any component replacement, major repair, or modification of components that could significantly affect the characteristics of the radiation beam.(D) Notwithstanding the requirements of subparagraph (C): (i) Full calibration of therapeutic radiation machines with multi-energy and/or multi-mode capabilities is required only for those modes and/or energies that are not within their acceptable range; and(ii) If the repair, replacement or modification does not affect all modes and/or energies, full calibration shall be performed on the effected mode/energy that is in most frequent clinical use at the facility. The remaining energies/modes may be validated with quality assurance check procedures against the criteria in clause (i).(2) To satisfy the requirement of paragraph (1), full calibration shall include all measurements required for annual calibration by American Association of Physicists in Medicine (AAPM) Report 13, "Physical Aspects of Quality Assurance in Radiation Therapy";(3) The licensee shall use the dosimetry system described in section 11-45-234(c) to measure the radiation output for one set of exposure conditions. The remaining radiation measurements required in paragraph (2) may then be made using a dosimetry system that indicates relative dose rates; and(4) The licensee shall maintain a record of each calibration for the duration of the license. The record shall include the date of the calibration, the manufacturer's name, model number, and serial number for the therapeutic radiation machine, the model numbers and serial numbers of the instruments used to calibrate the therapeutic radiation machine, and the signature of the qualified medical physicist responsible for performing the calibration.(u) Periodic quality assurance checks: (1) Periodic quality assurance checks shall be performed on all therapeutic radiation machines subject to this section at intervals not to exceed one week;(2) To satisfy the requirement of paragraph (1), quality assurance checks shall include determination of all parameters for periodic quality assurance checks contained in American Association of Physicists in Medicine (AAPM) Report 13, "Physical Aspects of Quality Assurance in Radiation Therapy";(3) The licensee shall use a dosimetry system which has been inter-compared within the previous six months with the dosimetry system described in section 11-45-234(c)(1) to make the periodic quality assurance checks required in paragraph (2);(4) The licensee shall perform periodic quality assurance checks required by paragraph (1) in accordance with procedures established by the qualified medical physicist;(5) The licensee shall review the results of each periodic radiation output check according to the following procedures: (A) The authorized user and qualified medical physicist shall be immediately notified if any parameter is not within its acceptable range. The therapeutic radiation machine shall not be made available for subsequent medical use until the qualified medical physicist has determined that all parameters are within their acceptable range;(B) If all quality assurance check parameters appear to be within their acceptable range, the quality assurance check shall be reviewed and signed by either the authorized user or qualified medical physicist within three treatment days; and(C) The qualified medical physicist shall review and sign the results of each radiation output quality assurance check at intervals not to exceed one month.(6) Therapeutic radiation machines subject to this section shall have safety quality assurance checks performed at intervals not to exceed one week;(7) To satisfy the requirement of paragraph (6), safety quality assurance checks shall ensure proper operation of: (A) Electrical interlocks at each external beam radiation therapy room entrance;(B) Proper operation of the "BEAM-ON", interrupt and termination switches;(C) Beam condition indicator lights on the access doors, control console, and in the radiation therapy room;(E) Electrically operated treatment room door(s) from inside and outside the treatment room;(F) At least one emergency power cutoff switch. If more than one emergency power cutoff switch is installed and not all switches are tested at once, each switch shall be tested on a rotating basis. Safety quality assurance checks of the emergency power cutoff switches may be conducted at the end of the treatment day in order to minimize possible stability problems with the therapeutic radiation machine.(8) The licensee shall promptly repair any system identified in paragraph (7) that is not operating properly; and(9) The licensee shall maintain a record of each quality assurance check required by paragraphs (1) and (7) for three years. The record shall include the date of the quality assurance check, the manufacturer's name, model number, and serial number for the therapeutic radiation machine, the manufacturer's name, model number and serial number of the instrument(s) used to measure the radiation output of the therapeutic radiation machine, and the signature of the individual who performed the periodic quality assurance check.[Eff 11/12/99] (Auth: HRS §§ 321-10, 321-11, 321-71) (Imp: HRS §§ 321-1, 321-11(21), 321-71)