General requirements for all diagnostic x-ray systems

In addition to other requirements of this chapter, all diagnostic x-ray systems shall meet the following requirements: 1. Warning label. The control panel containing the main power switch shall bear the warning statement, legible and accessible to view: "WARNING: This x-ray unit may be dangerous to patient and operator unless safe exposure factors and operating instructions are observed." 2. Battery charge indicator. On battery-powered x-ray generators, visual means shall be provided on the control panel to indicate whether the battery is in a state of charge adequate for proper operation. 3. Leakage radiation from the diagnostic source assembly. The leakage radiation from the diagnostic source assembly measured at a distance of one meter in any direction from the source shall not exceed one hundred milliroentgens in one hour when the x-ray tube is operated at its leakage technique factors. Compliance shall be determined by measurements averaged over an area of one hundred square centimeters with no linear dimension greater than twenty centimeters. 4. Radiation from components other than the diagnostic source assembly. The radiation emitted by a component other than the diagnostic source assembly shall not exceed two milliroentgens in one hour at five centimeters from any accessible surface of the component when it is operated in an assembled x-ray system under any conditions for which it was designed. Compliance shall be determined by measurements averaged over an area of one hundred square centimeters with no linear dimension greater than twenty centimeters. 5. Beam quality. a. Half-value layer. (1) The half-value layer (HVL) of the useful beam for a given x-ray tube potential shall not be less than the values shown in table I. If it is necessary to determine such half value layer at an x-ray tube potential which is not listed in table I, linear interpolation or extrapolation may be made. TABLE I Half-Value Layer in Millimeters Aluminum Design Operating Range (Kilovolts Peak) Measured Potential (Kilovolts Peak) Dental Intraoral Manufactured Before Aug. 1, 1974, and on or After Dec. 1, 1980 Diagnostic X-Ray Systems Manufactured Prior to June 10, 2006 Diagnostic X-Ray Systems Manufactured on or After June 10, 2006 Below 51 30 N/A 0.3 0.3 40 N/A 0.4 0.4 50 1.5 0.5 0.5 51 to 70 51 1.5 1.2 1.3 60 1.5 1.3 1.5 70 1.5 1.5 1.8 Above 70 71 2.1 2.1 2.5 80 2.3 2.3 2.9 90 2.5 2.5 3.2 100 2.7 2.7 3.6 110 3.0 3.0 3.9 120 3.2 3.2 4.3 130 3.5 3.5 4.7 140 3.8 3.8 5.0 150 4.1 4.1 5.4 (2) For capacitor energy storage equipment, compliance with the requirements of this subsection shall be determined with the system fully charged and a setting of ten mAs for each exposure. (3) The required minimal aluminum equivalent filtration shall include the filtration contributed by all materials which are permanently present between the source and the patient. (4) For mammography systems with molybdenum filter and molybdenum target, measured half-value layer (HVL) with compression device in the x-ray beam shall be greater than or equal to the kilovolts peak (kVp) divided by one hundred, millimeters aluminum and less than or equal to the kilovolts peak (kVp) divided by one hundred plus one-tenth millimeter aluminum. HVL > (kVp/100) mmAl and < (kVp/100) + 0.1 mmAl b. Filtration controls. For x-ray systems which have variable kilovolts peak and variable filtration for the useful beam, a device shall link the kilovolts peak selector with the filters and shall prevent an exposure unless the minimum amount of filtration required by paragraph 1 of subdivision a is in the useful beam for the given kilovolts peak which has been selected. 6. Multiple tubes. Where two or more radiographic tubes are controlled by one exposure switch, the tube or tubes which have been selected shall be clearly indicated prior to initiation of the exposure. This indication shall be both on the x-ray control panel and at or near the tube housing assembly which has been selected. 7. Mechanical support of tube head. The tube housing assembly supports shall be adjusted such that the tube housing assembly will remain stable during an exposure unless tube housing movement is a designed function of the x-ray system. 8. Technique indicators. a. The technique factors to be used during an exposure shall be indicated before the exposure begins, except when automatic exposure controls are used, in which case the technique factors which are set prior to the exposure shall be indicated. b. The requirements of subdivision a may be met by permanent markings on equipment having fixed technique factors. Indication of technique factors shall be visible from the operator's position except in the case of spot films made by the fluoroscopist. 9. Maintaining compliance. Diagnostic x-ray systems and their associated components used on humans and certified pursuant to the federal x-ray equipment performance standard (21 CFR part 1020) shall be maintained in compliance with applicable requirements of that standard. 10. Locks. All position locking, holding, and centering devices on x-ray system components and systems shall function as intended. 11. Structural shielding requirements (see appendix C).