South Carolina Code of Regulations
Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL
Subchapter 61-64 - X-Rays (Title B)
Part IV - USE OF X-RAYS IN THE HEALTH PROFESSIONS
Section 61-64.IV.RHB 4.11 - Computed Tomography (CT) X-ray Systems

Universal Citation: SC Code Regs 61-64.IV.RHB 4.11

Current through Register Vol. 48, No. 9, September 27, 2024

In addition to the applicable provisions of this regulation, the requirements of this Part apply to all stationary, transportable, and mobile CT X-ray systems.

4.11.1 Equipment Requirements.

4.11.1.1 Tomographic Plane Indication and Alignment.
4.11.1.1.1 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.

4.11.1.1.2 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.

4.11.1.1.3 If a device using a light source is used to satisfy the requirements of RHB 4.11.1.1.1 or 4.11.1.1.2, 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.

4.11.1.2 Indication of CT Conditions of Operation. The CT x-ray system shall be designed such that the CT conditions of operation to be used during a scan or a scan sequence shall be indicated prior to the initiation of a scan or a scan sequence. On equipment having all or some of these conditions of operation at fixed values, this requirement may be met by permanent markings. Indication of CT conditions of operation shall be visible from any position from which scan initiation is possible.

4.11.1.3 Beam-On and Shutter Status Indicators and Control Switches
4.11.1.3.1 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.

4.11.1.3.2 All emergency buttons or switches shall be clearly labeled as to their functions.

4.11.1.4 Termination of Exposure.
4.11.1.4.1 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 equipment failure affecting data collection. Such termination shall occur within an interval that limits the total scan time to no more than one hundred ten percent (110%) of its preset value through the use of either a backup timer or devices which monitor equipment function.

4.11.1.4.2 A visible signal shall indicate when the x-ray exposure has been terminated through the means required by RHB 4.11.1.4.1.

4.11.1.4.3 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 one-half (0.5) second duration.

4.11.1.5 Additional Requirements Applicable to CT X-ray Systems Containing a Gantry Manufactured After September 3, 1985.
4.11.1.5.1 The total error in the indicated location of the tomographic plane or reference plane shall not exceed five millimeters (5 mm).

4.11.1.5.2 If the x-ray production period is less than one-half (0.5) second, the indication of x-ray production shall be actuated for at least one-half (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.

4.11.1.5.3 The deviation of indicated scan increment versus actual increment shall not exceed to within one millimeter (1 mm) with any mass from zero to one hundred kilograms (0 to 100 kg) resting on the support device. The patient support device shall be incremented from a typical starting position to the maximum incremented distance or thirty centimeters (30 cm), whichever is less, and then returned to the starting position. Measurement of actual versus indicated scan increment can be taken anywhere along this travel.

4.11.1.5.4 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.

4.11.2 Facility Design Requirements.

4.11.2.1 The control panel and x-ray control must be mounted in a permanently protected area outside the computed tomography room. The operator is required to remain in that protected area during the entire exposure, except when performing procedures requiring the use of exposure switches located on or near the CT gantry and designed to provide a delay before initiating x-rays and provided all requirements of RHB 4.2.9 are met.

4.11.2.2 Aural Communication. Provision shall be made for two-way aural communication between the patient and the operator at the control panel.

4.11.2.3 Facilities designed with an open area in the control room that leads to the gantry shall mark this open area conspicuously and indicate not to stand or sit in this area during x-ray exposures.

4.11.2.4 Viewing Systems.
4.11.2.4.1 Windows, mirrors, closed-circuit television, or an equivalent 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.

4.11.2.4.2 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.

4.11.3 Equipment Performance Tests and Routine Quality Control

4.11.3.1 Equipment Performance Tests
4.11.3.1.1 Equipment performance tests shall be performed by a Class IX vendor.

4.11.3.1.2 Evaluation standards and tolerances shall be established by the Class IX vendor and maintained by the facility. These standards and tolerances shall meet nationally recognized standards and tolerances for the CT x-ray system and shall include the required minimum criteria for performance tests provided by Appendix F.

4.11.3.1.3 The measurements of the radiation output of the CT x-ray system shall be performed with a calibrated dosimetry system. The calibration of such system shall be traceable to a national standard. The dosimetry system shall have been calibrated within the preceding two (2) years.

4.11.3.1.4 Records of equipment performance tests performed shall be maintained for inspection by the Department.

4.11.3.2 Routine Quality Control (QC)
4.11.3.2.1 A routine QC program shall be developed by or have written approval by a Class IX vendor and include:
4.11.3.2.1.1 Instructions on performing routine QC;

4.11.3.2.1.2 Frequency and conditions of QC testing;

4.11.3.2.1.3 Acceptable tolerances for items evaluated; and

4.11.3.2.1.4 Daily use of a water equivalent phantom to evaluate CT number, noise, and artifacts.

4.11.3.2.2 The CT operator shall have access to the QC program and the results of the most recent routine QC completed on the system.

4.11.3.2.3 Routine QC records shall be documented and maintained for inspection by the Department. Records shall be maintained for two (2) years or the next Department inspection, whichever is later.

4.11.4 Ancillary personnel who are not necessary for the safety of the patient shall not be present in the area of the CT unit while exposures are being made.

4.11.5 Cone Beam Computed Tomography (CBCT) Systems

4.11.5.1 The registrant shall follow QC recommendations provided by the CBCT manufacturer. In the absence of manufacturer-provided QC recommendations, the registrant shall implement and document QC guidelines established by a Class IX vendor in accordance to nationally recognized guidelines or those recognized by the Department.

4.11.5.2 As applicable, all provisions of RHB 4.4 and 4.11 apply, except 4.11.2.4 and 4.11.3.2.1 through 4.11.3.2.2.

4.11.5.3 The minimum source-skin distance shall not be less than thirty centimeters (30 cm), except veterinary equipment.

4.11.5.4 Beam alignment. The x-ray field in the plane of the image receptor shall not exceed beyond the edge of the image receptor by more than two percent (2%) of the SID when the axis of the x-ray beam is perpendicular to the plane of the image receptor. In addition, the center of the x-ray field shall be aligned with the center of the image receptor to within two percent (2%) of the SID.

4.11.5.5 The registrant shall implement and document a policy addressing deviations from established protocols.

4.11.5.6 The following information shall be readily available to the CBCT operator:
4.11.5.6.1 Instructions on performing routine QC, including the use of the CBCT phantom(s);

4.11.5.6.2 A schedule of routine QC appropriate for the system;

4.11.5.6.3 Allowable variations set by the Class IX vendor, if required, for the indicated parameters; and

4.11.5.6.4 The results of at least the most recent routine QC completed on the system.

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