Florida Regulations 64E-5.508: X-Ray and Electron Therapy Systems with Energies of 1 MeV and Above
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(1) Definitions. In addition to the definitions in Fl. Admin. Code R. 64E-5.501, the following definitions shall apply to this section:
(a) “”Applicator”” means a structure which determines the extent of the treatment field at a given distance from the virtual source.
(b) “”Beam scattering filter”” means a filter used in order to scatter a beam of electrons.
(c) “”Central axis of the beam”” means a line passing through the virtual source and the center of the plane figure formed by the edge of the first beam limiting device.
(d) “”Dose monitoring system”” means a system of devices for the detection, measurement and display of quantities of radiation.
(e) “”Dose monitor unit”” means a unit response from the dose monitoring system from which the absorbed dose can be calculated.
(f) “”Field-flattening filter”” means a filter used to provide dose uniformity over the area of a useful beam of x-rays at a specified depth.
(g) “”Field size”” means the dimensions along the major axes of an area in a plane perpendicular to the specified direction of the beam of incident radiation at the normal treatment distance and defined by the intersection of the major axes and the 50% percent isodose line. Material shall be placed in the beam such that dose maximum is produced at the normal treatment distance when field size is being determined.
(h) “”Gantry”” means that part of the system supporting and allowing possible movements of the radiation head.
(i) “”Interruption of irradiation”” means the stopping of irradiation with the possibility of continuing irradiation without resetting of operating conditions at the control panel.
(j) “”Isocenter”” means a fixed point in space located at the center of the smallest sphere through which the central axis of the beam passes in all conditions.
(k) “”Moving beam therapy”” means radiation therapy with relative displacement of the useful beam and the patient during irradiation. It includes arc therapy, skip therapy and rotational therapy.
(l) “”Normal treatment distance”” means:
1. For electron irradiation, the virtual source to surface distance along the central axis of the useful beam as specified by the manufacturer for the applicator.
2. For x-ray irradiation, the virtual source to isocenter distance along the central axis of the useful beam. For nonisocentric equipment, this distance shall be that specified by the manufacturer.
(m) “”Radiation head”” means the structure from which the useful beam emerges.
(n) “”Shadow tray”” means a device attached to the radiation head to support auxiliary beam limiting material.
(o) “”Stationary beam therapy”” means radiation therapy without relative displacement of the useful beam or the patient during irradiation.
(p) “”Target”” means that part of a radiation head which by design intercepts a beam of accelerated particles with subsequent emission of other radiation.
(q) “”Virtual source”” means a point from which radiation appears to originate.
(2) Requirements for Equipment.
(a) Leakage Radiation to the Patient Area.
1. New equipment shall meet the following requirement: For operating conditions producing maximum leakage radiation, the absorbed dose in rads (grays) due to leakage radiation, including x-rays, electrons, and neutrons, at any point in a circular plane of 2 meters radius centered on and perpendicular to the central axis of the beam at the isocenter or normal treatment distance and outside the maximum useful beam size, shall not exceed 0.1% percent of the maximum absorbed dose in rads (grays) of the unattenuated useful beam measured at the point of intersection of the central axis of the beam and the plane surface. Measurements, excluding those for neutrons, shall be averaged over an area up to, but not exceeding, 100 square centimeters at the positions specified. Measurements of the portion of the leakage radiation dose contributed by neutrons may be obtained from the manufacturer and shall be averaged over an area up to, but not exceeding, 200 square centimeters.
2. The registrant shall determine or obtain from the manufacturer the leakage radiation existing at the positions specified and for the specified operating conditions. Records on radiation leakage shall be maintained for inspection by the Department.
(b) Leakage of Radiation Outside the Patient Area for New Equipment.
1. The absorbed dose in rads (grays) due to leakage radiation, except in the area specified in paragraph (2)(a), above, when measured at any point 1 meter from the path of the charged particle, before the charged particle strikes the target or window, shall not exceed 0.1 percent for x-ray leakage nor 0.05 percent for neutron leakage of the maximum absorbed dose in rads (grays) of the unattenuated useful beam measured at the point of intersection of the central axis of the beam and the circular plane specified in paragraph (2)(a), above.
2. The registrant shall determine or obtain from the manufacturer the actual leakage radiation existing at the positions specified and for specified operating conditions. Radiation measurements, excluding neutrons, shall be averaged over an area up to, but not exceeding, 100 square centimeters. Neutron measurements shall be averaged over an area up to, but not exceeding, 200 square centimeters.
(c) Beam Limiting Devices. Adjustable or interchangeable beam-limiting devices shall be provided, and such devices shall transmit no more than 5 percent of the useful beam at the normal treatment distance for the portion of the useful beam which is to be attenuated by the beam limiting device. The neutron component of the useful beam shall not be included in this requirement.
(d) Filters.
1. Each filter which is removable from the system shall be clearly marked with an identification number. Documentation available at the control panel shall contain a description of the filter. For wedge filters, the wedge angle shall appear on the wedge or wedge tray.
2. If the absorbed dose rate data indicated at the control panel 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 new equipment which utilizes a system of wedge filters, interchangeable field flattening filters or interchangeable beam scattering filters:
a. Irradiation shall not be possible until a selection of a filter has been made at the treatment control panel,
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 filter in use; and,
d. An interlock shall be provided to prevent irradiation if any filter selection operation carried out in the treatment room does not agree with the filter selection operation carried out at the treatment control panel.
(e) Beam Quality. The registrant shall determine, or obtain from the manufacturer, data sufficient to assure that the following beam quality requirements are met:
1. The absorbed dose resulting from x-rays in a useful electron beam at a point on the central axis of the beam 10 centimeters greater than the practical range of the electrons shall not exceed the values stated below. Linear interpolation shall be used for values not stated.
Maximum Energy of Electron Beam in MeV
X-Ray Absorbed Dose as a Fraction of Maximum Absorbed Dose
1
0.03
15
0.05
35
0.10
50
0.20
2. Compliance with subparagraph (2)(e)1., above, shall be determined using:
a. A measurement within a phantom with the incident surface of the phantom at the normal treatment distance and normal to the central axis of the beam:
b. The largest field size available which does not exceed 15 by 15 centimeters; and,
c. A phantom whose cross-sectional dimensions exceed the measurement radiation field by at least 5 centimeters and whose depth is sufficient to perform the required measurement.
(f) Beam Monitors. All therapy systems shall be provided with two radiation detectors in the radiation head.
1. The detectors shall be incorporated into two separate dose monitoring systems.
2. 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 shall be designed to prevent incorrect positioning.
b. Each detector shall form part of a dose monitoring system from whose readings in dose monitor units the absorbed dose at a reference point in the treatment volume can be calculated.
c. Each dose monitoring system shall be capable of independently monitoring, interrupting and terminating irradiation.
d. For new equipment, the design of the dose monitoring systems shall assure that:
(I) The malfunctioning of one system shall not affect the correct functioning of the second system; and,
(II) The failure of any element common to both systems which could affect the correct function of both systems shall terminate irradiation.
3. Each dose monitoring system shall have a legible display at the treatment control panel. For new equipment, each display shall:
a. Maintain a reading until intentionally reset to 0,
b. Have only one scale and no scale multiplying factors,
c. Utilize a design such that increasing dose is displayed by increasing numbers and in the event of an overdosage of radiation, the absorbed dose may be accurately determined; and,
d. In the event of power failure, the dose monitoring information required to be displayed at the control panel at the time of failure shall be retrievable in at least one system for a 20-minute period of time.
(g) Beam Symmetry. In equipment inherently capable of producing useful beams with asymmetry exceeding 5% percent, the asymmetry of the radiation beam in two orthogonal directions shall be monitored before the beam passes through the beam limiting device. Facilities shall be provided so that, if the difference in dose rate between one region and another region symmetrically displaced from the central axis of the beam exceeds 5% percent of the central axis dose rate, indication of this condition is made at the control panel; and if this difference exceeds 10% percent, the irradiation is terminated.
(h) Selection and Display of Dose Monitor Units.
1. Irradiation shall not be possible until a selection of a number of dose monitor units or exposure time has been made at the treatment control panel.
2. The pre-selected number of dose monitor units or exposure time 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 to 0 before subsequent treatment can be initiated.
4. After termination of irradiation, it shall be necessary to manually reset the pre-selected dose monitor units before irradiation can be initiated.
(i) Termination of Irradiation by the Dose Monitoring System or Systems During Stationary Beam Therapy.
1. Each primary system shall terminate irradiation when the pre-selected number of dose monitor units has been detected by the system.
2. The system shall be capable of terminating irradiation when not more than 10% percent or 30 dose monitoring units above the pre-selected number of dose monitor units set at the control panel has been detected by the second dose monitoring system.
3. An indicator on the control panel shall show which dose monitoring system has terminated irradiation.
(j) Interruption Switches. It shall be possible to interrupt irradiation and equipment movements at any time from the operator’s position at 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.
(k) Termination Switches. It shall be possible to terminate irradiation and equipment movements, or go from an interruption condition to termination conditions, at any time from the operator’s position at the treatment control panel.
(l) Timer.
1. A timer which has a display shall be provided at the treatment control panel. The timer shall have a pre-set time selector and an elapsed time indicator.
2. The timer shall be a cumulative timer which activates with the production of radiation 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 to 0.
3. After termination of irradiation and before irradiation can be reinitiated, it shall be necessary to manually reset the preset 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.
(m) Selection of Radiation Type. Equipment capable of both x-ray therapy and electron therapy shall meet the following:
1. Irradiation shall not be possible until a selection of radiation type has been made at the treatment control panel.
2. An interlock system shall be provided to ensure that the equipment can emit only the radiation type which has been selected.
3. 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.
4. An interlock system shall be provided to prevent irradiation with x-rays except to obtain a port 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.
6. The radiation type selected shall be displayed at the treatment control panel before and during irradiation.
(n) Selection of Energy. Equipment capable of generating radiation beams of different energies shall meet the following:
1. Irradiation shall not be possible until a selection of energy has been made at the treatment control panel.
2. 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.
3. The nominal energy value selected shall be displayed at the treatment control panel before and during irradiation.
(o) Selection of Stationary Beam Therapy or Moving Beam Therapy. Equipment capable of both stationary beam therapy and moving beam therapy shall meet the following:
1. Irradiation shall not be possible until a selection of stationary beam therapy or moving beam therapy has been made at the treatment control panel.
2. An interlock system shall be provided to ensure that the equipment can operate only in the mode which has been selected.
3. 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.
4. The mode of operation shall be displayed at the treatment control panel.
5. An interlock system shall be provided to terminate irradiation if:
a. Movement of the gantry occurs during stationary beam therapy, or
b. Movement of the gantry stops during moving beam therapy unless such stoppage is a preplanned function.
6. Moving beam therapy shall be controlled to obtain the selected relationships between incremental dose monitor units and incremental angle of movement.
a. An interlock system shall be provided to terminate irradiation if the number of dose monitor units delivered in any 10° degrees of arc differs by more than 20% percent from the selected value.
b. Where gantry angle terminates the irradiation in arc therapy, the dose monitor units shall differ by less than 5% percent from the value calculated from the absorbed dose per unit angle relationship.
7. Where the dose monitor system terminates the irradiation in arc therapy, the termination of irradiation shall be as required by paragraph (2)(i), above.
(p) Absorbed Dose Rate. A system shall be provided from whose readings the absorbed dose rate at a reference point in the treatment volume can be calculated. In addition:
1. The dose monitor unit rate shall be displayed at the treatment control panel; and,
2. The radiation detectors specified in paragraph (2)(f), above, may form part of this system.
(q) Location of Virtual Source and Beam Orientation. The registrant shall determine, or obtain from the manufacturer, the location with reference to an accessible point on the radiation head of:
1. The x-ray target or the virtual source of x-rays; and,
2. The electron window or the virtual source of electrons if the system has a electron beam capabilities.
(r) System Checking Facilities. Capabilities shall be provided so that all radiation safety interlocks can be checked for correct operation. When preselection of any of the operating conditions requires action in the treatment room and at the treatment control panel, selection at one location shall not give a display at the other location until the requisite selected operations in both locations have been completed.
(3) Facility and Shielding Requirements. In addition to Part III, the following design requirements shall apply:
(a) Protective Barriers. All protective barriers shall be fixed except for entrance doors or beam interceptors.
(b) Control Panel. The control panel shall be located outside the treatment room.
(c) Viewing System. Windows, mirrors, closed-circuit television, or an equivalent system shall be provided to permit continuous observation of the patient during irradiation and shall be so located that the operator may observe the patient from the control panel.
(d) Aural Communication. Provision shall be made for two-way aural communication between the patient and the operator at the control panel. However, where excessive noise levels or treatment requirements make aural communication impractical, other methods of communication shall be used.
(e) Room Entrance. Treatment room entrances shall be provided with warning lights in readily observable positions near the outside of all access doors or other entrances to indicate when the useful beam is on.
(f) Entrance Interlocks. Interlocks shall be provided such that all entrance doors must be closed before treatment can be initiated or continued. If the radiation beam is interrupted by any barrier penetration or 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.
(4) Surveys, Calibrations, Spot-Checks and Operating Procedures.
(a) Surveys.
1. All new facilities, and existing facilities not previously surveyed, shall have a survey made by, or under the direction of, a qualified person. In addition, such surveys shall be done after any change in the facility or equipment which might cause a significant increase in radiation hazard.
2. The registrant shall obtain a written report of the survey from the qualified person, and a copy of the report shall be transmitted by the registrant to the Department within 30 days of receipt of the report.
3. The survey and report shall indicate all instances where the installation, in the opinion of the qualified person, is in violation of applicable regulations.
(b) Calibration.
1. The calibration of systems subject to Fl. Admin. Code R. 64E-5.508, shall be performed in accordance with an established calibration protocol acceptable to the Department, such as the calibration protocol published by the American Association of Physicists in Medicine, before the system is first used for irradiation of a patient and thereafter at time intervals which do not exceed 12 months and after any change which might significantly alter the calibration, spatial distribution or other characteristics of the therapy beam.
2. The calibration shall be performed under the direct supervision of a radiological physicist who is physically present at the facility during the calibration.
3. Calibration radiation measurements required by paragraph (4)(b), above, shall be performed using a dosimetry system:
a. Having a calibration factor for cobalt 60 gamma rays traceable to a national standard,
b. Which has been calibrated within the previous 2 years and after any servicing that may have affected its calibration,
c. Which has been calibrated in such a fashion that an uncertainty can be stated for the radiation quantities monitored by the system; and,
d. Which has had constancy checks performed on the system as specified by a radiological physicist.
4. Calibrations shall be in sufficient detail that the dose at a reference point in soft tissue may be calculated to within an uncertainty of 5 percent.
5. The calibration of the therapy beam shall include the following determinations:
a. Verification that the equipment is operating in compliance with the design specifications concerning the light localizer, side light, and back-pointer alignment with the isocenter when applicable, variation in the axis of rotation for the table, gantry, and jaw system, and beam flatness and symmetry at the specified depth.
b. The absorbed dose rate at various depths of water for the range of field sizes used, for each effective energy, that will verify the accuracy of the dosimetry of all therapy procedures utilized with that therapy beam.
c. The uniformity of the radiation field and any dependency upon the direction of the useful beam.
d. Verification that existing depth-dose data and isodose charts applicable to the specific machine continue to be valid or are updated to existing machine conditions.
e. Verification of transmission and electron buildup factors for all accessories such as wedges, shadow trays, and compensators.
6. Records of calibration measurements and dosimetry system calibrations required in paragraph (4)(b), above, shall be maintained for 5 years after completion of the full calibration.
7. A copy of the latest calibration performed shall be available in the facility for inspection by the Department.
(c) Spot-Checks. Spot-checks shall be performed on systems subject to this section during calibrations and thereafter at intervals not to exceed 1 month. Such spot-checks shall meet the following requirements:
1. The spot-check procedures shall be in writing and shall have been developed by a radiological physicist. Acceptable tolerance for each parameter measured in the spot-check shall not exceed manufacturer’s recommendations.
2. If a radiological physicist does not perform the spot-check measurements, the results of the spot-check measurements shall be reviewed by a radiological physicist within 15 days.
3. The spot-check procedures shall specify the frequency at which tests or measurements are to be performed and the acceptable tolerance for each parameter measured in the spot-check when compared to the value for that parameter determined in the calibration.
4. At intervals established in the spot-check procedures, spot-checks shall be made of absorbed dose measurements at a minimum of 2 depths in a phantom.
5. Where a system has built-in devices which provide a measurement of any parameter during irradiation, such measurement shall not be utilized as a spot-check measurement.
6. The cause for a parameter exceeding a tolerance set by the radiological physicist shall be investigated and corrected before the system is used for patient irradiation.
7. Whenever a spot-check indicates a significant change in the operating characteristics of a system, as specified in the radiological physicist’s spot-check procedures, the system shall be recalibrated as required in paragraph (4)(b), above.
8. Records of spot-check measurements and any necessary corrective actions shall be maintained by the registrant for a period of 2 years.
9. Where a spot-check involves an absolute radiation measurement, such measurement shall be obtained using a system satisfying the requirements of subparagraph (4)(b)3., above, or which has been compared with a system meeting those requirements within the previous year.
(d) Additional Operating Procedures.
1. No individual other than the patient shall be in the treatment room during treatment of a patient.
2. If a patient must be held in position during treatment, mechanical supporting or restraining devices shall be used.
3. The system shall not be used in the administration of radiation therapy unless the requirements of paragraphs (4)(a), (4)(b) and (4)(c), above, have been met.
Rulemaking Authority 404.031, 404.051, 404.071, 404.081, 404.141, 404.22 FS. Law Implemented 404.022, 404.031, 404.051(1), (4), (5), (6), 404.071(1), 404.081(1), 404.141, 404.22(1), (3) FS. History-New 7-17-85, Amended 4-4-89, Formerly 10D-91.609, Amended 6-3-15.
(b) “”Beam scattering filter”” means a filter used in order to scatter a beam of electrons.
(c) “”Central axis of the beam”” means a line passing through the virtual source and the center of the plane figure formed by the edge of the first beam limiting device.
(d) “”Dose monitoring system”” means a system of devices for the detection, measurement and display of quantities of radiation.
(e) “”Dose monitor unit”” means a unit response from the dose monitoring system from which the absorbed dose can be calculated.
(f) “”Field-flattening filter”” means a filter used to provide dose uniformity over the area of a useful beam of x-rays at a specified depth.
(g) “”Field size”” means the dimensions along the major axes of an area in a plane perpendicular to the specified direction of the beam of incident radiation at the normal treatment distance and defined by the intersection of the major axes and the 50% percent isodose line. Material shall be placed in the beam such that dose maximum is produced at the normal treatment distance when field size is being determined.
(h) “”Gantry”” means that part of the system supporting and allowing possible movements of the radiation head.
(i) “”Interruption of irradiation”” means the stopping of irradiation with the possibility of continuing irradiation without resetting of operating conditions at the control panel.
(j) “”Isocenter”” means a fixed point in space located at the center of the smallest sphere through which the central axis of the beam passes in all conditions.
(k) “”Moving beam therapy”” means radiation therapy with relative displacement of the useful beam and the patient during irradiation. It includes arc therapy, skip therapy and rotational therapy.
(l) “”Normal treatment distance”” means:
1. For electron irradiation, the virtual source to surface distance along the central axis of the useful beam as specified by the manufacturer for the applicator.
2. For x-ray irradiation, the virtual source to isocenter distance along the central axis of the useful beam. For nonisocentric equipment, this distance shall be that specified by the manufacturer.
(m) “”Radiation head”” means the structure from which the useful beam emerges.
(n) “”Shadow tray”” means a device attached to the radiation head to support auxiliary beam limiting material.
(o) “”Stationary beam therapy”” means radiation therapy without relative displacement of the useful beam or the patient during irradiation.
(p) “”Target”” means that part of a radiation head which by design intercepts a beam of accelerated particles with subsequent emission of other radiation.
(q) “”Virtual source”” means a point from which radiation appears to originate.
(2) Requirements for Equipment.
(a) Leakage Radiation to the Patient Area.
1. New equipment shall meet the following requirement: For operating conditions producing maximum leakage radiation, the absorbed dose in rads (grays) due to leakage radiation, including x-rays, electrons, and neutrons, at any point in a circular plane of 2 meters radius centered on and perpendicular to the central axis of the beam at the isocenter or normal treatment distance and outside the maximum useful beam size, shall not exceed 0.1% percent of the maximum absorbed dose in rads (grays) of the unattenuated useful beam measured at the point of intersection of the central axis of the beam and the plane surface. Measurements, excluding those for neutrons, shall be averaged over an area up to, but not exceeding, 100 square centimeters at the positions specified. Measurements of the portion of the leakage radiation dose contributed by neutrons may be obtained from the manufacturer and shall be averaged over an area up to, but not exceeding, 200 square centimeters.
2. The registrant shall determine or obtain from the manufacturer the leakage radiation existing at the positions specified and for the specified operating conditions. Records on radiation leakage shall be maintained for inspection by the Department.
(b) Leakage of Radiation Outside the Patient Area for New Equipment.
1. The absorbed dose in rads (grays) due to leakage radiation, except in the area specified in paragraph (2)(a), above, when measured at any point 1 meter from the path of the charged particle, before the charged particle strikes the target or window, shall not exceed 0.1 percent for x-ray leakage nor 0.05 percent for neutron leakage of the maximum absorbed dose in rads (grays) of the unattenuated useful beam measured at the point of intersection of the central axis of the beam and the circular plane specified in paragraph (2)(a), above.
2. The registrant shall determine or obtain from the manufacturer the actual leakage radiation existing at the positions specified and for specified operating conditions. Radiation measurements, excluding neutrons, shall be averaged over an area up to, but not exceeding, 100 square centimeters. Neutron measurements shall be averaged over an area up to, but not exceeding, 200 square centimeters.
(c) Beam Limiting Devices. Adjustable or interchangeable beam-limiting devices shall be provided, and such devices shall transmit no more than 5 percent of the useful beam at the normal treatment distance for the portion of the useful beam which is to be attenuated by the beam limiting device. The neutron component of the useful beam shall not be included in this requirement.
(d) Filters.
1. Each filter which is removable from the system shall be clearly marked with an identification number. Documentation available at the control panel shall contain a description of the filter. For wedge filters, the wedge angle shall appear on the wedge or wedge tray.
2. If the absorbed dose rate data indicated at the control panel 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 new equipment which utilizes a system of wedge filters, interchangeable field flattening filters or interchangeable beam scattering filters:
a. Irradiation shall not be possible until a selection of a filter has been made at the treatment control panel,
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 filter in use; and,
d. An interlock shall be provided to prevent irradiation if any filter selection operation carried out in the treatment room does not agree with the filter selection operation carried out at the treatment control panel.
(e) Beam Quality. The registrant shall determine, or obtain from the manufacturer, data sufficient to assure that the following beam quality requirements are met:
1. The absorbed dose resulting from x-rays in a useful electron beam at a point on the central axis of the beam 10 centimeters greater than the practical range of the electrons shall not exceed the values stated below. Linear interpolation shall be used for values not stated.
Maximum Energy of Electron Beam in MeV
X-Ray Absorbed Dose as a Fraction of Maximum Absorbed Dose
1
0.03
15
0.05
35
0.10
50
0.20
2. Compliance with subparagraph (2)(e)1., above, shall be determined using:
a. A measurement within a phantom with the incident surface of the phantom at the normal treatment distance and normal to the central axis of the beam:
b. The largest field size available which does not exceed 15 by 15 centimeters; and,
c. A phantom whose cross-sectional dimensions exceed the measurement radiation field by at least 5 centimeters and whose depth is sufficient to perform the required measurement.
(f) Beam Monitors. All therapy systems shall be provided with two radiation detectors in the radiation head.
1. The detectors shall be incorporated into two separate dose monitoring systems.
2. 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 shall be designed to prevent incorrect positioning.
b. Each detector shall form part of a dose monitoring system from whose readings in dose monitor units the absorbed dose at a reference point in the treatment volume can be calculated.
c. Each dose monitoring system shall be capable of independently monitoring, interrupting and terminating irradiation.
d. For new equipment, the design of the dose monitoring systems shall assure that:
(I) The malfunctioning of one system shall not affect the correct functioning of the second system; and,
(II) The failure of any element common to both systems which could affect the correct function of both systems shall terminate irradiation.
3. Each dose monitoring system shall have a legible display at the treatment control panel. For new equipment, each display shall:
a. Maintain a reading until intentionally reset to 0,
b. Have only one scale and no scale multiplying factors,
c. Utilize a design such that increasing dose is displayed by increasing numbers and in the event of an overdosage of radiation, the absorbed dose may be accurately determined; and,
d. In the event of power failure, the dose monitoring information required to be displayed at the control panel at the time of failure shall be retrievable in at least one system for a 20-minute period of time.
(g) Beam Symmetry. In equipment inherently capable of producing useful beams with asymmetry exceeding 5% percent, the asymmetry of the radiation beam in two orthogonal directions shall be monitored before the beam passes through the beam limiting device. Facilities shall be provided so that, if the difference in dose rate between one region and another region symmetrically displaced from the central axis of the beam exceeds 5% percent of the central axis dose rate, indication of this condition is made at the control panel; and if this difference exceeds 10% percent, the irradiation is terminated.
(h) Selection and Display of Dose Monitor Units.
1. Irradiation shall not be possible until a selection of a number of dose monitor units or exposure time has been made at the treatment control panel.
2. The pre-selected number of dose monitor units or exposure time 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 to 0 before subsequent treatment can be initiated.
4. After termination of irradiation, it shall be necessary to manually reset the pre-selected dose monitor units before irradiation can be initiated.
(i) Termination of Irradiation by the Dose Monitoring System or Systems During Stationary Beam Therapy.
1. Each primary system shall terminate irradiation when the pre-selected number of dose monitor units has been detected by the system.
2. The system shall be capable of terminating irradiation when not more than 10% percent or 30 dose monitoring units above the pre-selected number of dose monitor units set at the control panel has been detected by the second dose monitoring system.
3. An indicator on the control panel shall show which dose monitoring system has terminated irradiation.
(j) Interruption Switches. It shall be possible to interrupt irradiation and equipment movements at any time from the operator’s position at 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.
(k) Termination Switches. It shall be possible to terminate irradiation and equipment movements, or go from an interruption condition to termination conditions, at any time from the operator’s position at the treatment control panel.
(l) Timer.
1. A timer which has a display shall be provided at the treatment control panel. The timer shall have a pre-set time selector and an elapsed time indicator.
2. The timer shall be a cumulative timer which activates with the production of radiation 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 to 0.
3. After termination of irradiation and before irradiation can be reinitiated, it shall be necessary to manually reset the preset 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.
(m) Selection of Radiation Type. Equipment capable of both x-ray therapy and electron therapy shall meet the following:
1. Irradiation shall not be possible until a selection of radiation type has been made at the treatment control panel.
2. An interlock system shall be provided to ensure that the equipment can emit only the radiation type which has been selected.
3. 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.
4. An interlock system shall be provided to prevent irradiation with x-rays except to obtain a port 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.
6. The radiation type selected shall be displayed at the treatment control panel before and during irradiation.
(n) Selection of Energy. Equipment capable of generating radiation beams of different energies shall meet the following:
1. Irradiation shall not be possible until a selection of energy has been made at the treatment control panel.
2. 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.
3. The nominal energy value selected shall be displayed at the treatment control panel before and during irradiation.
(o) Selection of Stationary Beam Therapy or Moving Beam Therapy. Equipment capable of both stationary beam therapy and moving beam therapy shall meet the following:
1. Irradiation shall not be possible until a selection of stationary beam therapy or moving beam therapy has been made at the treatment control panel.
2. An interlock system shall be provided to ensure that the equipment can operate only in the mode which has been selected.
3. 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.
4. The mode of operation shall be displayed at the treatment control panel.
5. An interlock system shall be provided to terminate irradiation if:
a. Movement of the gantry occurs during stationary beam therapy, or
b. Movement of the gantry stops during moving beam therapy unless such stoppage is a preplanned function.
6. Moving beam therapy shall be controlled to obtain the selected relationships between incremental dose monitor units and incremental angle of movement.
a. An interlock system shall be provided to terminate irradiation if the number of dose monitor units delivered in any 10° degrees of arc differs by more than 20% percent from the selected value.
b. Where gantry angle terminates the irradiation in arc therapy, the dose monitor units shall differ by less than 5% percent from the value calculated from the absorbed dose per unit angle relationship.
7. Where the dose monitor system terminates the irradiation in arc therapy, the termination of irradiation shall be as required by paragraph (2)(i), above.
(p) Absorbed Dose Rate. A system shall be provided from whose readings the absorbed dose rate at a reference point in the treatment volume can be calculated. In addition:
1. The dose monitor unit rate shall be displayed at the treatment control panel; and,
2. The radiation detectors specified in paragraph (2)(f), above, may form part of this system.
(q) Location of Virtual Source and Beam Orientation. The registrant shall determine, or obtain from the manufacturer, the location with reference to an accessible point on the radiation head of:
1. The x-ray target or the virtual source of x-rays; and,
2. The electron window or the virtual source of electrons if the system has a electron beam capabilities.
(r) System Checking Facilities. Capabilities shall be provided so that all radiation safety interlocks can be checked for correct operation. When preselection of any of the operating conditions requires action in the treatment room and at the treatment control panel, selection at one location shall not give a display at the other location until the requisite selected operations in both locations have been completed.
(3) Facility and Shielding Requirements. In addition to Part III, the following design requirements shall apply:
(a) Protective Barriers. All protective barriers shall be fixed except for entrance doors or beam interceptors.
(b) Control Panel. The control panel shall be located outside the treatment room.
(c) Viewing System. Windows, mirrors, closed-circuit television, or an equivalent system shall be provided to permit continuous observation of the patient during irradiation and shall be so located that the operator may observe the patient from the control panel.
(d) Aural Communication. Provision shall be made for two-way aural communication between the patient and the operator at the control panel. However, where excessive noise levels or treatment requirements make aural communication impractical, other methods of communication shall be used.
(e) Room Entrance. Treatment room entrances shall be provided with warning lights in readily observable positions near the outside of all access doors or other entrances to indicate when the useful beam is on.
(f) Entrance Interlocks. Interlocks shall be provided such that all entrance doors must be closed before treatment can be initiated or continued. If the radiation beam is interrupted by any barrier penetration or 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.
(4) Surveys, Calibrations, Spot-Checks and Operating Procedures.
(a) Surveys.
1. All new facilities, and existing facilities not previously surveyed, shall have a survey made by, or under the direction of, a qualified person. In addition, such surveys shall be done after any change in the facility or equipment which might cause a significant increase in radiation hazard.
2. The registrant shall obtain a written report of the survey from the qualified person, and a copy of the report shall be transmitted by the registrant to the Department within 30 days of receipt of the report.
3. The survey and report shall indicate all instances where the installation, in the opinion of the qualified person, is in violation of applicable regulations.
(b) Calibration.
1. The calibration of systems subject to Fl. Admin. Code R. 64E-5.508, shall be performed in accordance with an established calibration protocol acceptable to the Department, such as the calibration protocol published by the American Association of Physicists in Medicine, before the system is first used for irradiation of a patient and thereafter at time intervals which do not exceed 12 months and after any change which might significantly alter the calibration, spatial distribution or other characteristics of the therapy beam.
2. The calibration shall be performed under the direct supervision of a radiological physicist who is physically present at the facility during the calibration.
3. Calibration radiation measurements required by paragraph (4)(b), above, shall be performed using a dosimetry system:
a. Having a calibration factor for cobalt 60 gamma rays traceable to a national standard,
b. Which has been calibrated within the previous 2 years and after any servicing that may have affected its calibration,
c. Which has been calibrated in such a fashion that an uncertainty can be stated for the radiation quantities monitored by the system; and,
d. Which has had constancy checks performed on the system as specified by a radiological physicist.
4. Calibrations shall be in sufficient detail that the dose at a reference point in soft tissue may be calculated to within an uncertainty of 5 percent.
5. The calibration of the therapy beam shall include the following determinations:
a. Verification that the equipment is operating in compliance with the design specifications concerning the light localizer, side light, and back-pointer alignment with the isocenter when applicable, variation in the axis of rotation for the table, gantry, and jaw system, and beam flatness and symmetry at the specified depth.
b. The absorbed dose rate at various depths of water for the range of field sizes used, for each effective energy, that will verify the accuracy of the dosimetry of all therapy procedures utilized with that therapy beam.
c. The uniformity of the radiation field and any dependency upon the direction of the useful beam.
d. Verification that existing depth-dose data and isodose charts applicable to the specific machine continue to be valid or are updated to existing machine conditions.
e. Verification of transmission and electron buildup factors for all accessories such as wedges, shadow trays, and compensators.
6. Records of calibration measurements and dosimetry system calibrations required in paragraph (4)(b), above, shall be maintained for 5 years after completion of the full calibration.
7. A copy of the latest calibration performed shall be available in the facility for inspection by the Department.
(c) Spot-Checks. Spot-checks shall be performed on systems subject to this section during calibrations and thereafter at intervals not to exceed 1 month. Such spot-checks shall meet the following requirements:
1. The spot-check procedures shall be in writing and shall have been developed by a radiological physicist. Acceptable tolerance for each parameter measured in the spot-check shall not exceed manufacturer’s recommendations.
2. If a radiological physicist does not perform the spot-check measurements, the results of the spot-check measurements shall be reviewed by a radiological physicist within 15 days.
3. The spot-check procedures shall specify the frequency at which tests or measurements are to be performed and the acceptable tolerance for each parameter measured in the spot-check when compared to the value for that parameter determined in the calibration.
4. At intervals established in the spot-check procedures, spot-checks shall be made of absorbed dose measurements at a minimum of 2 depths in a phantom.
5. Where a system has built-in devices which provide a measurement of any parameter during irradiation, such measurement shall not be utilized as a spot-check measurement.
6. The cause for a parameter exceeding a tolerance set by the radiological physicist shall be investigated and corrected before the system is used for patient irradiation.
7. Whenever a spot-check indicates a significant change in the operating characteristics of a system, as specified in the radiological physicist’s spot-check procedures, the system shall be recalibrated as required in paragraph (4)(b), above.
8. Records of spot-check measurements and any necessary corrective actions shall be maintained by the registrant for a period of 2 years.
9. Where a spot-check involves an absolute radiation measurement, such measurement shall be obtained using a system satisfying the requirements of subparagraph (4)(b)3., above, or which has been compared with a system meeting those requirements within the previous year.
(d) Additional Operating Procedures.
1. No individual other than the patient shall be in the treatment room during treatment of a patient.
2. If a patient must be held in position during treatment, mechanical supporting or restraining devices shall be used.
3. The system shall not be used in the administration of radiation therapy unless the requirements of paragraphs (4)(a), (4)(b) and (4)(c), above, have been met.
Rulemaking Authority 404.031, 404.051, 404.071, 404.081, 404.141, 404.22 FS. Law Implemented 404.022, 404.031, 404.051(1), (4), (5), (6), 404.071(1), 404.081(1), 404.141, 404.22(1), (3) FS. History-New 7-17-85, Amended 4-4-89, Formerly 10D-91.609, Amended 6-3-15.