La. Admin. Code tit. 33 § XV-608

Current through Register Vol. 50, No. 11, November 20, 2024

Section XV-608 - Therapeutic X-Ray Systems of Less Than 1 MeV

A. Equipment Requirements

1. 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 classification of that X-ray system, as follows.

a. Contact Therapy Systems. Leakage radiation shall not exceed 100 milliroentgens (25.8 [MICRO]C/kg) per hour at 5 centimeters from the surface of the tube housing assembly.

b. 0-150 kVp Systems. Systems that were manufactured or installed prior to April 20, 1977, shall have a leakage radiation that does not exceed 1 roentgen (0.258 mC/kg) in one hour at 1 meter from the source.

c. 0-150 kVp Systems. Systems manufactured on or after April 20, 1977, shall have a leakage radiation that does not exceed 100 milliroentgens (25.8 [MICRO]C/kg) in one hour at 1 meter from the source; and

d. 151-999 kVp Systems. Leakage radiation shall not exceed 1 roentgen (0.258 mC/kg) in one hour at 1 meter from the source, except that systems that operate in excess of 500 kVp may have a leakage radiation at 1 meter from the source not to exceed 0.1 percent of the useful beam 1 meter from the source.

2. 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.

3. Removable and Adjustable Beam-Limiting Devices. These devices shall meet the following requirements:

a. 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. The requirement does not apply to auxiliary blocks or materials placed in the useful beam to shape the useful beam to the individual patient;

b. adjustable beam-limiting devices installed after April 20, 1977, shall meet the requirements of LAC 33:XV.608.A.3.a; and

c. adjustable beam-limiting devices installed before April 20, 1977, shall, for the portion of the X-ray beam to be blocked by these devices, transmit not more than 5 percent of the useful beam at the maximum kilovoltage and maximum treatment filter.

4. Filtration. The filter system shall be so designed that it meets the following requirements:

a. the filters cannot be accidentally displaced at any possible tube orientation;

b. 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;

c. it shall be possible for the operator to determine the presence or absence of each filter and the operation of each wedge filter in the useful beam when the operator is at his or her position at the control panel either by display at the control panel or by direct observation; and

d. the radiation at 5 centimeters from the filter insertion slot opening does not exceed 30 roentgens (7.74 mC/kg) per hour under any operating condition.

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

6. 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.

7. 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.

8. Beam Monitor System. Systems of greater than 150 kVp manufactured after April 20, 1977, shall be provided with a beam monitor system that:

a. shall have the detector of the monitor system interlocked to prevent incorrect positioning;

b. shall not allow irradiation until a preselected value of exposure has been made at the treatment control panel;

c. shall independently terminate irradiation when the preselected exposure has been reached;

d. 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;

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

f. shall have a control panel display that maintains the administered dose reading until intentionally reset to zero; and

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

9. Timer. Requirements for timers are as follows:

a. a timer that has a display shall be provided at the treatment control panel. The timer shall have a preset time selector and an elapsed time indicator;

b. the timer shall be a cumulative timer that 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 zero;

c. the timer shall terminate irradiation when a preselected time has elapsed if any dose monitoring system present has not previously terminated irradiation;

d. the timer shall permit accurate presetting and determination of exposure times as short as one second;

e. the timer shall not permit an exposure if set at zero; and

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

10. Control Panel Functions. The control panel, in addition to the displays required in other provisions of LAC 33:XV.608, shall have:

a. an indication of whether electrical power is available at the control panel and if activation of the X-ray tube is possible;

b. an indication of whether X-rays are being produced;

c. a means for indicating X-ray tube potential and current;

d. a means for terminating an exposure at any time;

e. a locking device that will prevent unauthorized use of the X-ray system; and

f. for X-ray systems manufactured after April 20, 1977, a positive display of specific filter(s) in the beam.

11. Multiple Tubes. When a control panel may energize more than one X-ray tube, the following requirements apply:

a. it shall be possible to activate only one X-ray tube at any time;

b. there shall be an indication at the control panel identifying which X-ray tube is energized; and

c. there shall be an indication at the tube housing assembly when that tube is energized.

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

13. Shutters. Unless it is possible to bring the X-ray output to the prescribed exposure parameters within five seconds, the beam shall be automatically attenuated by a shutter having a lead equivalency not less than that of the tube housing assembly. In addition:

a. after the unit is at operating parameters, the shutter shall be controlled electrically by the operator from the control panel; and

b. an indication of shutter position shall appear at the control panel.

14. 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.

B. Facility Design Requirements for X-Ray Systems Capable of Operating above 50 kVp

1. 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.

2. Viewing Systems. Provisions shall be made as follows:

a. 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; and

b. when the primary viewing system is by electronic means, an alternate viewing system, which may be electronic, shall be available for use in the event of failure of the primary viewing system.

3. Additional Requirements for X-Ray Systems Capable of Operation above 150 kVp. Additional requirements are:

a. all protective barriers shall be fixed except for entrance doors or beam interceptors;

b. the control panel shall be located outside the treatment room;

c. entrance 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, 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; and

d. when any door referred to in LAC 33:XV.608.B.3.c is opened while the X-ray tube is activated, the exposure at a distance of 1 meter from the source shall be reduced to less than 100 milliroentgens (25.8 [MICRO]C/kg) per hour.

C. Surveys, Calibrations, Spot Checks, and Operating Procedures

1. Survey requirements are as follows:

a. all new facilities, and existing facilities not previously surveyed, shall have a survey made by, or under the direction of, a qualified expert. In addition, such surveys shall be done after any change in the facility or equipment that might cause a significant increase in radiation hazard;

b. the registrant or licensee shall obtain a written report of the survey from the qualified expert, and a copy of the report shall be transmitted by the registrant or licensee to the Office of Environmental Compliance within 30 calendar days of receipt of the report; and

c. the survey and report shall indicate all instances where the installation, in the opinion of the qualified expert, is in violation of applicable rules.

2. Calibrations shall be performed as follows:

a. the calibration of an X-ray system shall be performed at intervals not to exceed one year and after any change or replacement of components that could cause a change in the radiation output;

b. the calibration of the radiation output of the X-ray system shall be performed by, or under the direction of, a qualified expert who is physically present at the facility during such calibration;

c. 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 two years;

d. the calibrations shall be such that the dose at a reference point in soft tissue can be calculated to within an uncertainty of 5 percent;

e. the calibration of the X-ray system shall include, but not be limited to, the following determinations:

i. verification that the X-ray system is operating in compliance with the design specifications;

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

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

iv. an evaluation of the uniformity of the largest radiation field used;

f. records of calibration shall be maintained by the registrant or licensee for five years after completion of the calibration at the facility of use; and

g. a copy of the most recent X-ray system calibration shall be available at or in the area of the control panel.

3. Spot checks shall be performed on X-ray systems capable of operation at greater than 150 kVp. Such spot checks shall meet the following requirements:

a. the spot-check procedures shall be in writing and shall have been developed by a qualified expert. A copy of the procedures shall be submitted to the Office of Environmental Compliance prior to their implementation;

b. if a qualified expert does not perform the spot-check measurement, the results of the spot-check measurements shall be reviewed by a qualified expert within 15 calendar days;

c. 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 LAC 33:XV.608.C.2. 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 LAC 33:XV.608.C.2 shall be stated;

d. the cause for a parameter exceeding a tolerance set by the qualified expert shall be investigated and corrected before the system is used for patient irradiation;

e. whenever a spot check indicates a significant change in the operating characteristics of a system, as specified in the qualified expert's spot-check procedures, the system shall be recalibrated as required in LAC 33:XV.608.C.2;

f. records of spot-check measurements shall be maintained by the registrant or licensee for two years after completion of the spot-check measurements and any necessary corrective actions at the facility of use; and

g. where a spot check involves a radiation measurement, such measurement shall be obtained using a system satisfying the requirements of LAC 33:XV.608.C.2 or that has been intercompared with a system meeting those requirements within the previous year.

4. Operating procedures shall include the following:

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

b. when a patient must be held in position for radiation therapy, mechanical supporting or restraining devices shall be used;

c. 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 mm lead equivalency at 100 kVp;

d. 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 LAC 33:XV.410. No individual other than the patient shall be in the treatment room during exposures from X-ray systems operating above 150 kVp; and

e. the X-ray system shall not be used in the administration of radiation therapy unless the requirements of LAC 33:XV.608.C.2 and 608.C.3.e have been met.

La. Admin. Code tit. 33, § XV-608

Promulgated by the Department of Environmental Quality, Nuclear Energy Division, LR 13:569 (October 1987), amended by the Office of Air Quality and Radiation Protection, Radiation Protection Division, LR 19:1421 (November 1993), amended by the Office of Environmental Assessment, Environmental Planning Division, LR 26:2586 (November 2000), amended by the Office of the Secretary, Legal Affairs Division, LR 31:2532 (October 2005), LR 33:2185 (October 2007).

AUTHORITY NOTE: Promulgated in accordance with R.S. 30:2001 et seq.