Section He-P 4046.13 - Computed Tomography X-ray Systems - Surveys, Calibrations, Spot Checks, and Operating Procedures(a) All CT x-ray systems shall have a survey made by or under the direction of a qualified expert.(b) The registrant shall obtain a written report of the survey from the qualified expert, and a copy of the report shall be made available to DHHS/RHS upon request.(c) The calibration of the radiation output of the CT 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.(d) The calibration of a CT x-ray system shall be performed at intervals specified by a qualified expert and after any change or replacement of components which, in the opinion of the qualified expert, could cause a change in the radiation output.(e) The calibration of the radiation output of a CT x-ray system shall be performed with a calibrated dosimetry system which is traceable to a national standard and has been calibrated within the preceding 2 years.(f) CT dosimetry phantom(s) shall meet the following specifications and conditions of use shall be used in determining the radiation output of a CT X-ray system: (1) CT dosimetry phantom(s) shall be right circular cylinders of polymethyl methacrylate of density 1.19 plus or minus 0.01 grams per cubic centimeter;(2) The phantom(s) shall be at least 14 centimeters in length and shall have diameters of 32.0 centimeters for testing CT x-ray systems designed to image any section of the body and 16.0 centimeters for systems designed to image the head or for whole body scanners operated in the head scanning mode;(3) CT dosimetry phantom(s) shall provide means for the placement of a dosimeter(s) along the axis of rotation and along a line parallel to the axis of rotation 1.0 centimeter from the outer surface and within the phantom; and(4) All dose measurements shall be performed with the CT dosimetry phantom placed on the patient couch or support device without additional attenuation materials present.(g) The calibration shall be required for each type of head, body, or whole-body scan performed at the facility.(h) Calibration shall meet the following requirements: (1) The dose profile along the center axis of the CT dosimetry phantom for the minimum, maximum, and midrange values of the nominal tomographic section thickness used by the registrant shall be measurable;(2) Where less than 3 nominal tomographic thicknesses can be selected, the dose profile determination shall be performed for each available nominal tomographic section thickness;(3) The CTDI along the two axes specified in He-P 4046.02(l) (1) shall be measured;(4) The CT dosimetry phantom shall be oriented so that the measurement point 1.0 centimeter from the outer surface and within the phantom is in the same angular position within the gantry as the point of maximum surface CTDI identified; and(5) The CT conditions of operation shall correspond to typical values used by the registrant for body parts represented by that phantom type.(i) Calibration procedures shall be in writing.(j) Records of calibrations performed shall be maintained for inspection by DHHS/RHS.(k) The spot check procedures shall be in writing and shall have been developed by a qualified expert.(l) The spot check procedures shall incorporate the use of a CT dosimetry phantom capable of providing an indication of contrast scale, noise, nominal tomographic section thickness, resolution capability of the system for low and high contrast objects, and measuring the mean CTN for water or other reference material.(m) All spot checks shall be included in the CT calibration and at time intervals and under system conditions specified by a qualified expert.(n) 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 calibrations.(o) The spot check images shall be retained, until a new calibration is performed, as images stored in digital form on a backed-up storage medium compatible with the CT x-ray system.(p) Written records of the spot checks performed shall be maintained for inspection by DHHS/RHS.(q) The CT x-ray system shall not be operated except by a person who has been specifically trained in its operation.(r) Information shall be available at the control panel regarding the operation and calibration of the system to include the following: (1) Dates of the latest calibration and spot-checks and the location within the facility where the results of those tests may be obtained;(2) Instructions on the use of the CT dosimetry phantom(s) including a schedule of spot-checks appropriate for the system, allowable variations for the indicated parameters, and the results of at least the most recent spot-checks conducted on the system;(3) The distance in millimeters between the tomographic plane and the reference plane if a reference plane is utilized;(4) A current technique chart available at the control panel which specifies for each routine examination the CT conditions of operation and the number of scans per examination; and(5) If the calibration or spot- check of the CT x-ray system identifies that a system operating parameter has exceeded a tolerance established by the qualified expert, use of the CT x-ray system on patients shall be limited to those uses permitted by established written instructions of the qualified expert.N.H. Code Admin. R. He-P 4046.13
#6827, eff 8-6-98; ss by #8692, INTERIM, eff 7-27-06, EXPIRES: 2-2-07; ss by #8808, eff 1-24-07
Amended byVolume XXXV Number 06, Filed February 12, 2015, Proposed by #10763, Effective 1/23/2015, Expires7/22/2015.Amended by Volume XXXV Number 32, Filed August 13, 2015, Proposed by #10893, Effective 7/21/2015, Expires7/21/2025.