Section R12-1-611. Therapeutic X-ray Systems of Less Than 1 MeV

A.      Equipment requirements.

1.        Leakage radiation. When the x-ray tube is operated at its maximum rated tube current for the maximum kVp, the leakage air kerma rate shall not exceed the value speci- fied at the distance specified for that classification of therapeutic radiation machine. For each therapeutic radia- tion machine, the registrant shall determine, or obtain from the manufacturer, the leakage radiation existing at the positions specified:

a.         5-50 kVp Systems. The leakage air kerma rate mea- sured at any position 5 centimeters from the tube housing assembly shall not exceed 1 mGy (100 mrad) in any one hour.

b.        Greater than 50 kVp and less than 1MeV Systems. The leakage air kerma rate measured at a distance of 1 meter from the target in any direction shall not exceed 1 centigray (1 rad) in any 1 hour. This air kerma rate measurement may be averaged over areas no larger than 100 square centimeters (100 cm2). In addition, the air kerma rate at a distance of 5 centi- meters from the surface of the tube housing assem- bly shall not exceed 30 centigray (30 rad) per hour.

2.        Permanent beam limiting devices. A registrant shall ensure that fixed diaphragms or cones used for limiting the useful beam provide the same or higher degree of attenuation as required for the tube housing assembly.

3.        Removable and adjustable beam-limiting devices. A reg- istrant shall ensure that:

a.         Removable and adjustable beam-limiting devices, for the portion of the useful beam to be blocked by these devices, transmit not more than 1 percent of the original x-ray beam at the maximum kilovoltage and maximum treatment filter; and

b.        When adjustable beam limiting devices are used, the position and shape of the radiation field shall be indicated by a light beam.

4.        Filter system. A registrant shall ensure that the filter sys- tem is designed so that:

a.         Filters cannot be accidentally displaced from the useful beam at any possible tube orientation;

b.        For equipment installed after January 1, 2011, an interlock system prevents irradiation if the proper filter is not in place;

c.         The air kerma rate escaping from the filter slot shall not exceed 1 centiGray (1 rad) per hour at one (1) meter under any operating conditions; and

d.        Each filter is marked regarding its material of con- struction and its thickness or wedge angle for wedge filters.

5.        X-ray tube immobilization. A registrant shall ensure that the tube housing assembly is capable of being immobi- lized during stationary treatments and the x-ray tube shall be so mounted that it cannot accidentally turn or slide with respect to the housing aperture.

6.        Focal spot marking. A registrant shall ensure that the tube housing assembly is marked so that it is possible to deter- mine the location of the focal spot to within 5 millime- ters, and the marking is readily accessible for use during calibration procedures.

7.        Therapy treatment timers. A registrant shall:

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

b.        Ensure that the timer is a cumulative timer that acti- vates with the radiation, retains its reading after irra- diation is interrupted or terminated, and requires the operator to reset the preset time selector after irradi- ation is terminated and before irradiation can be reinitiated;

c.         Ensure that the timer terminates irradiation when a preselected time has elapsed;

d.        Ensure that the timer permits accurate presetting and determination of exposure times as short as one sec- ond;

e.         Ensure that the timer does not permit an exposure if set at zero; and

f.         Ensure that the timer does not activate until the shut- ter is opened if irradiation is controlled by a shutter mechanism.

8.        Control panel functions. In addition to the displays required in other provisions of this Section, a registrant shall ensure that a control panel has:

a.         An indication of whether electrical power is avail- able 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 kVp and x-ray tube 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 equipment installed after January 2, 1996, a positive display of specific filters in the beam.

9.        Multiple tubes. If one control panel is used to energize more than one x-ray tube a registrant shall ensure that:

a.         It is possible to activate only one x-ray tube during any time interval,

b.        There is an indication at the control panel that identi- fies which x-ray tube is energized, and

c.         There is an indication at the tube housing assembly when that tube is energized.

10.     Source-to-patient distance. A registrant shall ensure that there is a means of determining the source-to-patient dis- tance to within 1 centimeter.

11.     Shutters. Unless it is possible to bring the x-ray output to the prescribed exposure parameters within five seconds, a registrant shall ensure that the entire useful beam is auto- matically attenuated by a shutter with a lead equivalency not less than that of the tube housing assembly. In addi- tion the registrant shall ensure that:

a.         After the unit is at operating parameters, the opera- tor controls the shutter electrically from the control panel; and

b.        An indication of shutter position appears at the con- trol panel.

12.     Low filtration x-ray tubes. A registrant shall ensure that each x-ray system equipped with a beryllium or other low-filtration window is clearly labeled as low-filtration equipment on the tube housing assembly and at the con- trol panel.

B.       Facility design requirements. In addition to shielding neces- sary to meet the requirements of Article 4 of this Chapter, a registrant shall ensure that:

1.        Warning lights. A treatment room to which access is pos- sible through more than one entrance has a warning light, in a readily observable position near the outside of any access doors, which will indicate when the useful beam is “on.”

2.        Voice communication. Two-way oral communication is possible between the patient and the operator at the con- trol panel; or where excessive noise levels make oral communication impractical, another effective method of communication.

3.        Viewing systems. Windows, mirrors, closed-circuit tele- vision, or an equivalent system, permits continuous observation of the patient during irradiation and is located so that the operator can observe the patient from the con- trol panel. If the primary viewing system is by electronic means (for example, television), the registrant shall have an alternate viewing system for use in the event of elec- tronic failure.

4.        Systems above 150 kVp. For treatment rooms that con- tain an x-ray system capable of operating above 150 kVp a registrant shall ensure that:

a.         All necessary shielding, except for any beam inter- ceptor, is provided by fixed barriers;

b.        The control panel is within a protective booth equipped with an interlocked door, or located out- side the treatment rooms;

c.         All doors of the treatment room are electrically con- nected to the control panel so that x-ray production cannot occur unless all doors are closed; and

d.        Opening of any door to the treatment room during exposure results in automatic termination of x-ray production or  reduction  of  radiation  levels  to  an average of no more than 516 nC/kg (2 milliroent- gens) per hour and a maximum of 2.6 µC/kg (10 milliroentgens) per hour at a distance of 1 meter (3.3 feet) from the target in any direction, and restoration of the machine to full operation is possible only from the control panel after the termination or reduc- tion.

C.      Surveys. A registrant shall ensure that:

1.        All facilities, both new and existing, or not previously surveyed, are surveyed before being put into service for the treatment of patients by, or under the direction of, a person trained and experienced in the principles of radia-

tion protection, and perform additional surveys of a facil- ity after any change in the facility or a facility’s equipment that might cause a significant increase in radi- ation hazard, before being put into service for the treat- ment of patients.

2.        The person conducting the survey reports the survey find- ings in writing to the individual in charge of the facility and maintains a copy of the survey report for inspection by the Agency.

3.        The installation is operated in compliance with any lim- itations indicated by the protection survey required by subsection (C)(1).

D.      Calibrations. A registrant shall ensure that:

1.        The calibration of a therapeutic x-ray system includes, but is not limited to, the following determinations:

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

b.        The dose rate equivalent for each combination of field size, technique factors, filter, and treatment dis- tance used;

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

d.        An evaluation of the uniformity of the radiation field symmetry for the field sizes used and any depen- dence upon source housing assembly orientation;

2.        The calibration of an x-ray system is performed at inter- vals not to exceed annually and after any change or replacement of components that could cause a change in the radiation output;

3.        The calibration of the radiation output of the x-ray system is performed by, or under the direction of, a person trained and experienced in performing calibrations, who is physically present at the facility during calibration;

4.        Calibration of the radiation output of an x-ray system is performed with a calibrated instrument. The registrant shall ensure that calibration of the instrument is directly traceable to the National Institute of Standards and Tech- nology (NIST) and that the instrument has been cali- brated within the preceding 24 months;

5.        Records of calibration performed under subsection (D)(3) are maintained for at least three years after completion of the calibration and are made available for inspection by the Agency; and

6.        A copy of the most recent calibration is available for use by the operator at the control panel.

E.       Spot checks. A registrant shall ensure that spot checks are per- formed on therapeutic x-ray systems capable of operation at greater than 150 kVp. The registrant shall ensure that spot checks meet the following requirements:

1.        The spot-check procedures are in writing and have been developed by a qualified expert;

2.        The measurements taken during the spot checks demon- strate the degree of consistency of the operating charac- teristics that can affect the radiation output of the x-ray system;

3.        The written spot-check procedure specifies the frequency of the tests or measurements, made at intervals not to exceed monthly;

4.        The spot-check procedure identifies conditions that require recalibration of the system in accordance with subsection (D)(l); and

5.        Records of spot-check measurements performed as required by subsection (E)(3) are maintained, available for inspection by the Agency, for three years following the measurements.

F.       Operating procedures. A registrant shall ensure that:

1.        Therapeutic x-ray systems are not left unattended unless the system is secured according to subsection (A)(8)(e);

2.        If a patient must be held in position for radiation therapy, mechanical supporting or restraining devices are used;

3.        The tube housing assembly is not held by an individual during exposures; and

4.        At 150 kVp or more the patient is the only person in the treatment room during production of radiation. At less than 150 kVp an individual may be in the room with patient, provided the individual is protected by a barrier sufficient to meet the requirements of Article 4 of this Chapter.

G.      Electronic Brachytherapy units are exempt from the require- ments of this Section.

Historical Note

Adopted effective June 30, 1977 (Supp. 77-3). Former Section R12-1-611 repealed, new Section R12-1-611 adopted effective August 8, 1986 (Supp. 86-4). Amended

effective January 2, 1996 (Supp. 96-1). Amended by final

rulemaking at 9 A.A.R. 4302, effective November 14,

2003 (Supp. 03-3). Amended by final rulemaking at 15

A.A.R. 1023, effective August 1, 2009 (Supp. 09-2). Amended by final rulemaking at 19 A.A.R. 3882, effec-

tive January 4, 2014 (Supp. 13-4).