64E-5.507. Therapeutic X-Ray Systems of Less Than 1 MeV

(1) Equipment Requirements.

(a) Leakage Radiation. When the tube is operated at its leakage technique factors, the leakage radiation shall not exceed the value specified at the distance specified for the following classification of that x-ray system:

1. Contact Therapy Systems. Leakage radiation shall not exceed 100 milliroentgens (25.8 uC per kg) per hour at 5 centimeters from the surface of the tube housing assembly.

2. Zero to One Hundred Fifty kVp Systems. Leakage radiation shall not exceed 100 milliroentgens (25.8 uC per kg) in 1 hour at 1 meter from the source.

3. One Hundred Fifty-one to Nine Hundred Ninety-nine kVp Systems. The leakage radiation shall not exceed 0.1 percent of the useful beam 1 meter from the source, for any of its operating conditions.

(b) Permanent Beam Limiting Devices. Permanent fixed diaphragms or cones used for limiting the useful beam shall provide the same or a higher degree of protection as required for the tube housing assembly.

(c) Removable and Adjustable Beam Limiting Devices.

1. Removable beam limiting devices shall, for the portion of the useful beam to be blocked by these devices, transmit not more than 1 percent of the useful beam at the maximum kilovoltage and maximum treatment filter. This requirement does not apply to auxiliary blocks or materials placed in the useful beam to shape the useful beam to the individual patient.

2. Adjustable beam limiting devices shall transmit not more than 5 percent of the useful beam at the maximum kilovoltage and with the maximum treatment filter in the useful beam.

(d) Filter System. The filter system shall be so designed that:

1. The filters cannot be accidentally displaced at any possible tube orientation;

2. The radiation at 5 centimeters from the filter insertion slot opening does not exceed 30 roentgens (7.7 mC per kg) per hour under any operating conditions;

3. Each filter is marked as to its material of construction and its thickness. For wedge filters, the wedge angle shall appear on the wedge or wedge tray; and

4. A filter indication system shall be used on all therapy machines using changeable filters. It shall be designed to permit easy recognition of any added filter in place. The presence or absence of any filter shall be discernible at the control panel.

(e) Tube Immobilization. The tube housing assembly shall be capable of being immobilized for stationary treatments.

(f) Focal Spot Marking. The tube housing assembly shall be so marked that it is possible to determine the location of the focal spot to within 5 millimeters, and such marking shall be readily accessible for use during calibration procedures.

(g) Beam Block. Contact therapy tube housing assemblies shall have a removable shield of at least 0.5 millimeter lead equivalency at 100 kVp that can be positioned over the entire useful beam exit port during periods when the beam is not in use.

(h) Beam Monitor System. Systems of greater than 150 kVp manufactured after January 1, 1985, shall be provided with a beam monitor system which:

1. Shall have the detector of the monitor system interlocked to prevent incorrect positioning;

2. Shall not allow irradiation until a pre-selected value of exposure has been made at the treatment control panel;

3. Shall independently terminate irradiation when the preselected exposure has been reached;

4. Shall be so designed that, in the event of a system malfunction or electrical power failure, the dose administered to a patient prior to the system malfunction or power failure can be accurately determined;

5. Shall have a display at the control panel from which the dose at a reference point in soft tissue can be calculated;

6. Shall have a control panel display which maintains the administered dose reading until intentionally reset to 0; and

7. Shall have a control panel display which does not have scale multiplying factors and utilizes a design such that increasing dose is displayed by increasing numbers.

(i) 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. The time shall terminate irradiation when a preselected time has elapsed if any dose monitoring system present has not previously terminated irradiation.

4. The timer shall permit accurate presetting and determination of exposure times as short as 1 second.

5. The timer shall not activate until the shutter is opened when irradiation is controlled by a shutter mechanism.

(j) Control Panel Functions. The control panel, in addition to the displays required in other provisions of this section, shall have:

1. An indication of whether electrical power is available at the control panel and if activation of the x-ray tube is possible;

2. An indication of whether x-rays are being produced;

3. Means for indicating x-ray tube potential and current;

4. Means for terminating an exposure at any time; and

5. A locking device which will prevent unauthorized use of the x-ray system.

(k) Multiple Tubes. When a control panel may energize more than one x-ray tube:

1. It shall be possible to activate only one x-ray tube at any time;

2. There shall be an indication at the control panel identifying which x-ray tube is energized; and

3. There shall be an indication at the tube housing assembly when that tube is energized.

(l) Source-to-Skin Distance (SSD). There shall be means of determining the SSD to within 1 centimeter.

(m) Low Filtration X-Ray Tubes. Each x-ray system equipped with a beryllium or other low-filtration window shall be clearly labeled as such upon the tube housing assembly and at the control panel.

(2) Facility Design Requirements for X-Ray Systems Operable Above 50 kVp.

(a) 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.

(b) Viewing Systems. 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 can observe the patient from the control panel.

(c) Additional Requirements for X-Ray Systems Operable Above 150 kVp:

1. All protective barriers shall be fixed except for entrance doors or beam interceptors.

2. The control panel shall be located outside the treatment room.

3. 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 door opening:

a. The exposure at a distance of 1 meter from the source shall be reduced to less than 10 milliroentgens (2.58 uC per kg) per hour; and

b. 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. Treatment rooms to which access is possible through more than one entrance shall be provided with flashing warning lights located in a readily observable position near the outside of all access doors to indicate when the useful beam is on.

(3) 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 transmit a copy of the survey report to the Department within 30 days of the 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) Calibrations.

1. The calibration of an x-ray system shall be performed at intervals not to exceed 1 year and after any change or replacement of components which could cause a change in the radiation output.

2. The calibration of the radiation output of an x-ray system shall be performed by or under the direction of a radiological physicist who is physically present at the facility during such calibration.

3. Calibration of the radiation output of an x-ray system shall be performed with a calibrated dosimetry system. The calibration of such system shall be traceable to a national standard. The system shall have been calibrated within the preceding 2 years.

4. The calibration shall be such that the dose at a reference point in soft tissue can be calculated to within an uncertainty not to exceed 5 percent.

5. The calibration of the x-ray system shall include, but not be limited to, the following determinations:

a. Verification that the x-ray system is operating in compliance with the design specifications;

b. The exposure rates as a function of field size, technique factors, filter and treatment distance used;

c. The degree of congruence between the radiation field and the field indicated by the localizing device if such device is present; and

d. An evaluation of the uniformity of the largest radiation field used.

6. Records of calibration shall be maintained by the registrant for 5 years after completion of the calibration.

7. A copy of the most recent x-ray system calibration shall be available at the facility for inspection by the Department.

(c) Spot-Checks. Spot-checks shall be performed on x-ray systems operable at greater than 150 kVp. 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.

2. If a radiological physicist does not perform the spot-check measurement, 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. The spot-check procedures shall specify that the spot-check shall be performed during the calibration specified in (3)(b), above. The acceptable tolerance for each parameter measured in the spot-check when compared to the value for that parameter determined in the calibration specified in (3)(a), above, shall be stated.

4. 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.

5. Whenever a spot-check indicates a significant change in the operating characteristics of a system, the system shall be recalibrated as required in (3)(b), above.

6. Records of spot-check measurements and any necessary corrective actions shall be maintained by the registrant for 2 years.

7. Where a spot-check involves a radiation measurement, such measurement shall be obtained using a system satisfying the requirements of (3)(b), above, or which has been compared within the previous year with a system meeting those requirements.

(d) Operating Procedures.

1. X-ray systems shall not be left unattended unless the system is secured against unauthorized use.

2. When a patient must be held in position for radiation therapy, mechanical supporting or restraining devices shall be used.

3. The tube housing assembly shall not be held by hand during operation unless the system is designed to require such holding and the peak tube potential of the system does not exceed 50 kVp. In such cases, the holder shall wear protective gloves and apron of not less than 0.5 millimeter lead equivalency at 100 kVp.

4. No individual other than the patient shall be in the treatment room unless such individual is protected by a barrier sufficient to meet the requirements of Rule 64E-5.304, F.A.C. No individual other than the patient shall be in the treatment room during exposures from x-ray systems operating above 150 kVp.

5. Machines capable of having an output of more than 1,000 roentgens (258 mC per kg) per minute at any accessible place shall not be left unattended without the power being shut off at the disconnect switch in addition to the control panel switch.

Rulemaking Authority 404.051, 404.081, 404.141, 404.22 FS. Law Implemented 404.022, 404.051(1), (4), (5), (6), 404.081(1), 404.22(1), (3) FS. History–New 7-17-85, Amended 1-1-94, Formerly 10D-91.608.