Oklahoma Administrative Code
Title 310 - Oklahoma State Department of Health
Chapter 281 - Medical Marijuana Regulations [Revoked]
Subchapter 11 - Use of X-Rays in the Healing Arts and Veterinary Medicine
Section 310:281-11-15 - Computed tomography x-ray systems

(A) For any single tomogram system, means shall be provided to permit visual determination of the tomographic plane or a reference plane offset from the tomographic plane.

(B) For any multiple tomogram system, means shall be provided to permit visual determination of the location of a reference plane. The reference plane can be offset from the location of the tomographic planes.

(C) If a device using a light source is used to satisfy 310:281-11-15(a)(1)(A) or (B), the light source shall provide illumination levels sufficient to permit visual determination of the location of the tomographic plane or reference plane under ambient light conditions of up to 500 lux.

(A) The x-ray control and gantry shall provide visual indication whenever x-rays are produced and, if applicable, whether the shutter is open or closed.

(B) Means shall be provided to require operator initiation of each individual scan or series of scans.

(C) All emergency buttons/switches shall be clearly labeled as to their functions.

(A) Means shall be provided to terminate the x-ray exposure automatically by either de-energizing the x-ray source or shuttering the x-ray beam in the event of the equipment failure affecting data collection. Such termination shall occur within an interval that limits the total scan time to no more than 110 percent of its preset value through the use of either a backup timer or devices which monitor equipment function.

(B) A visible signal shall indicate when the x-ray exposure has been terminated through the means required by 310:281-11-15(a)(4)(A).

(C) The operator shall be able to terminate the x-ray exposure at any time during a scan, or series of scans under x-ray system control, of greater than 0.5 second duration. Termination of the x-ray exposure shall necessitate resetting of the CT conditions of operation prior to initiation of another scan.

(A) The total error in the indicated location of the tomographic plane or reference plane shall not exceed 5 millimeters.

(B) If the x-ray production period is less than 0.5 second, the indication of x-ray production shall be activated for at least 0.5 second. Indicators at or near the gantry shall be discernible from any point external to the patient opening where insertion of any part of the human body into the primary beam is possible.

(C) The deviation of indicated scan increment versus actual increment shall not exceed to within 1 millimeter with any mass from O to 100 kilograms resting on the support device. The patient support device shall be incremented from a typical starting position to the maximum incremented distance or 30 centimeters, whichever is less, and then returned to the starting position. Measurement of actual versus indicated scan increment can be taken anywhere along this travel.

(D) Premature termination of the x-ray exposure by the operator shall necessitate resetting of the CT conditions of operation prior to the initiation of another scan.

(A) Windows, mirrors, closed-circuit television, or an equivalent shall be provided to permit continuous observation of the patient during irradiation and positioned to allow the operator to observe the patient from the control panel.

(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.

(A) All CT systems shall have a survey made by or under the direct supervision of a medical physicist.

(B) Performance surveys by a medical physicist shall be made:

(C) The permittee shall obtain a written report of the survey from the medical physicist and a copy of the report shall be made available to the Department upon request.

(A) The dose measurements of the radiation output of the CT system will be done by a medical physicist. Dose limits for adult head, adult abdomen, and pediatric abdomen are listed in 310:281-11-5.

(B) Any calibration or recalibration on a CT system required by the medical physicist's survey shall be done by a qualified service representative. Any work deemed necessary by the permittee, other than that permitted by the manufactures' operators manual, shall be performed by a qualified service representative.

(C) Calibration of the dose measurements of a CT system is required for each type of head, body, or whole-body scan performed at the facility.

(D) Dose measurements shall meet the following requirements:

(E) Calibration of the dose measurements of a CT equipment shall be performed with a calibrated dosimetry system.

(A) CT dosimetry phantom(s) shall be made of a material analogous to human tissue. (Water and acrylic are acceptable). If they are made of acrylic, they should have a density of 1.19 plus or minus 0.01 grams per cubic centimeter. The phantom(s) shall be at least 14 centimeters in length and have a diameter of 32.0 centimeters for testing CT systems designed to image any section of the body and 16.0 centimeters for equipment designed to image the head or for whole body equipment operated in the head scanning mode.

(B) CT dosimetry phantoms shall provide a means for the placement of a dosimeter(s) along the axis of rotation and a line parallel to the axis of rotation 1.0 centimeter from the outer surface and within the phantom. Means for the placement of dosimeter or alignment devices at other locations should be provided.

(C) Any effects on the doses measured due to the removal of phantom material to accommodate dosimeters shall be accounted for through appropriate corrections to the reported data or included in the statement of maximum deviation for the values obtained using the phantom.

(D) All dose measurements shall be performed with the CT phantom placed on the patient couch or support devices without additional attenuation materials present.

(E) If contrast studies are done, the materials used should be made of water, acrylic, polyethelene, and air. They will be used to simulate bone and different types of tissue.

(A) Spot check procedures shall be developed by a medical physicist.

(B) All spot checks shall be included in the medical physicist survey required by 310:281-11-15(c)(2), and otherwise at time intervals and under equipment conditions specified by a medical physicist.

(C) Spot checks shall include acquisition of images obtained with the CT dosimetry phantom(s) using the same processing mode and CT conditions of operation as are used to perform dose measurements required by 310:281-11-15(c)(2). The images shall be retained, until a new dose measurement is performed, in two forms as follows:

(D) Written records of the spot checks performed shall be maintained for inspection by the Department.

(A) The CT system shall not be operated except by an individual who has been specifically trained in its operation. Documentation of this training must be available upon request of the Department inspector.

(B) Information shall be available at the control panel regarding the operation and calibration of the system. Such information shall include the following.

(C) If the medical physicist survey or spot checks of the CT system identifies that a systems operating parameter(s) has exceeded a tolerance established by the medical physicist, use of the CT equipment on patients shall be limited to those uses permitted by established written instructions of the medical physicist.