A floor plan of the areas surrounding the treatment room that were surveyed.
The radiation level at several points in each area expressed in microsieverts or millirems per hour.
The calculated maximum level of radiation over a period of one week for each restricted and unrestricted area.
If the results of radiation protection surveys indicate any radiation levels in excess of the respective limit, the registrant shall lock the control in the "OFF" position and may not use the unit except under one or more of the following conditions:
As may be necessary to repair, replace or test the therapeutic radiation machine, the therapeutic radiation machine shielding or the treatment room shielding.
Until the registrant has received a specific exemption from the department.
(2) Modification of radiation therapy unit or room before beginning a treatment program.
If the survey indicates that a person in an unrestricted area may be exposed to levels of radiation greater than those permitted by s. DHS 157.23 (1) (a)
, before beginning the treatment program, the registrant shall do all of the following:
Include in the report the results of the initial survey, a description of the modification made and the results of the second survey.
Submit facility design information to the department prior to installation of a therapeutic radiation machine of higher energy into a room not previously approved for that energy and receive approval from the department prior to actual installation of the therapeutic radiation machine.
A registrant shall have a calibrated dosimetry system available for use. The dosimetry system shall be calibrated by a certified calibration facility at least every 24 months and after any servicing that may affect system calibration.
For beams with energies greater than one MeV, the dosimetry system shall be calibrated for Cobalt-60.
For beams with energies equal to or less than one MeV, the dosimetry system shall be calibrated at an energy or energy range appropriate for the radiation being measured.
A registrant shall have a dosimetry system for quality control check measurements. The system may be compared with another system whose calibration is traceable to the national institute of standards and technology. The comparison shall be performed at least every 24 months and after each servicing that may affect system calibration.
A registrant shall maintain a record of each dosimetry system calibration, intercomparison and comparison for the duration of the registration. For each calibration, intercomparison or comparison, the record shall include all of the following:
The model and serial numbers of the instruments that were calibrated, inter-compared or compared.
The names of the persons who performed the calibration, intercomparison or comparison.
Evidence that the intercomparison was performed by or under the direct supervision and in the physical presence of a medical physicist.
(4) Survey instruments.
Except for dermatology offices with systems operating at less than 150 kV, each facility location authorized to use a therapeutic radiation machine shall possess appropriately calibrated portable monitoring equipment. Equipment shall include a portable radiation measurement survey instrument capable of measuring dose rates over the range 10 mSv (one mrem) per hour to 10 mSv (1000 mrem) per hour. The survey instruments shall be operable and calibrated.
Facility design information for all new installations of a therapeutic radiation machine or installations of a therapeutic radiation machine of higher energy into a room not previously approved for that energy shall be submitted to the department and approved by the department prior to actual installation of the therapeutic radiation machine.
Observation and communication with the patient shall be possible at all times.
DHS 157.84 History
History: CR 01-108
: cr. Register July 2002 No. 559
, eff. 8-1-02.
Therapeutic radiation machines. DHS 157.85(1)(a)(a)
When a therapeutic radiation machine is operated at its maximum dose rate, the leakage air kerma rate may not exceed the value specified at the distance specified for that classification of therapeutic radiation machine.
Leakage radiation from contact therapy systems may not exceed one mGy (103 mR) per hour at 5 centimeters from the surface of the tube housing assembly. Contact therapy tube housing assemblies shall have a removable shield of material, equivalent in attenuation to 0.5 millimeters of lead at 100 kV, which may be positioned over the entire useful beam exit port during periods when the beam is not in use.
Leakage radiation from systems operating at 150 kV or less may not exceed one mGy (103 mR) per hour at one meter from the tube housing.
Leakage radiation from systems operating above 150 kV may not exceed 0.1% of the useful beam one meter from the source housing for any of its operating conditions.
(2) Permanent beam-limiting devices.
Permanent, non-adjustable collimators used for limiting the useful beam shall provide at least the same degree of attenuation as required for the tube housing assembly.
(3) Adjustable or removeable beam-limiting devices. DHS 157.85(3)(a)(a)
All removable beam-limiting devices or diaphragms may not transmit more than one percent of the useful beam for the most penetrating beam used. This paragraph does not apply to beam shaping blocks or shaping materials.
When adjustable beam-limiting devices are used, the position and shape of the useful beam shall be indicated by a light beam. These devices may transmit not more than 5% of the useful beam.
(4) Filter systems.
The filter system shall be designed to meet all of the following requirements:
Accidental displacement of filters is not possible at any tube orientation.
If the proper filter is not in place, an interlock system shall prevent irradiation.
The air kerma rate escaping from the filter placement opening slot in the tube head may not exceed 100 mGy (one rad) per hour at one meter under any operating conditions.
Each filter shall be marked as to its material of construction and its thickness.
Each wedge filter that 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 the wedge or wedge tray is significantly damaged, the wedge transmission factor shall be reestablished.
If the absorbed dose rate information relates exclusively to operation with a field flattening filter or beam scattering foil in place, that foil or filter shall be removable only by the use of tools.
An x-ray tube shall be mounted so that it cannot accidentally turn or slide with respect to the opening in the tube housing through which radiation is emitted.
The tube housing assembly shall be capable of being immobilized.
(6) Emergency switches.
At least one emergency power cutoff switch shall be present. 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 control checks of the emergency power cutoff switches may be conducted at the end of the treatment day to minimize possible stability problems with the therapeutic radiation machine.
(7) Source marking.
An x-ray tube housing assembly shall be marked so that it is possible to determine the location of the focal spot to within 5 millimeters and the marking shall be readily accessible for use during calibration procedures.
A suitable irradiation control device shall be provided to terminate the irradiation after a preset time interval or after a preset radiation dose has been delivered.
A timer with a display shall be provided at the treatment control panel. The timer shall have a pre-set time selector and an elapsed time or time remaining indicator.
A timer shall be a cumulative timer that activates with an indication of "BEAM-ON" and retains its reading after irradiation is interrupted or terminated. After irradiation is terminated and before irradiation may be reinitiated, it shall be necessary to reset the elapsed time indicator.
A timer shall terminate irradiation when a pre-selected time has elapsed, if any dose monitoring system present has not previously terminated irradiation.
A timer may not activate until the shutter is opened when irradiation is controlled by a shutter mechanism unless calibration includes a timer end effect correction to compensate for mechanical lag.
A timer shall be accurate to within one percent of the selected value or one second, whichever is greater.
(9) Control panel indicators.
An x-ray unit shall have all of the following:
An indication at the control panel of whether electrical power is on and if activation of the x-ray tube is possible.
A locking device that will prevent unauthorized use of the therapeutic radiation machine.
(10) Target to skin distance.
There shall be a means of determining the central axis target to skin distance to within 2 millimeters and of reproducing this measurement to within 2 millimeters thereafter.
Unless it is possible to bring the x-ray tube output to the prescribed exposure parameters within 5 seconds after the x-ray "ON" switch is energized, the beam shall be attenuated by a shutter having a shielding equivalency not less than that of the tube housing assembly. In addition, after the unit is at operating parameters, the shutter shall be controlled by the operator from the control panel. An indication of shutter position shall appear at the control panel.
(12) Low filtration machines.
Each therapeutic radiation machine equipped with a beryllium or other low filtration window shall be clearly labeled on the tube housing assembly and shall be provided with a permanent warning device on the control panel that is activated when no additional filtration is present, to indicate that the dose rate is very high.
Full calibration of a therapeutic radiation machine shall be performed by or under the direct supervision of a medical physicist under all of the following conditions:
Before the first medical use following installation or reinstallation of the therapeutic radiation machine.
Whenever quality control check measurements indicate that the radiation output differs by more than 5% from the value obtained at the last full calibration and the difference cannot be reconciled.
Following any component replacement, major repair or modification of components that could significantly affect the characteristics of the radiation beam.
Full calibration of therapeutic radiation machines with multi-energy capabilities is required only for those operational modes or radiation energies that are not within their acceptable range.
If the repair, replacement or modification does not affect all energies, full calibration shall be performed on the affected energy that is in most frequent clinical use at the facility. The remaining energies may be validated with quality control check procedures.
Full calibration shall include all measurements recommended for annual calibration by protocols approved by recognized national or international organizations. An acceptable protocol is the "Protocol for clinical reference dosimetry of high-energy photon and electron beams" as stated in AAPM Report No. 67, American Association of Physicists in Medicine, 1999.
DHS 157.85 Note
Report No. 67 "Protocol for Clinical Reference Dosimetry of High-Energy Photon and Electron Beams," was published in Medical Physics, 26 (9), September 1999, pp. 1847-70. The report may also be obtained from: Medical Physics Publishing, 4531 Vernon Blvd., Madison WI 53705-4964 or ordered from their website: www.medicalphysics.org
A registrant shall maintain a record of each calibration for the duration of the registration. The record shall include all of the following:
The manufacturer's name, model and serial number for both the therapeutic radiation machine and the x-ray tube.
The model and serial numbers of the instruments used to calibrate the therapeutic radiation machine.
The signature of the medical physicist responsible for performing the calibration.
Full calibration for electronic brachytherapy units shall include all of the following:
The output within 2% of the expected value, if applicable, or determination of the output if there is no expected value.
Evaluation that the relative dose distribution about the source is within 5% of the expected value.