Revista de Métodos de Diagnóstico Médico
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Abstrato

Determination of Calibration Cycles Using X-ray Tube Output, Workload and Use Factor for Diagnostic X-rays

Exeter J, Surujpaul PP

The stipulated standard time according to annual inspection done under the Health Facility Act 2008 is once per year however, due to varying workloads, use factor, and tube age the calibration cycles can be adjusted. Significance of this work includes determining the optimal calibration time of diagnostic X-ray tubes, resulting in promotion of new knowledge and influencing policies on the need for timely calibrations, additionally it may be used as a marker for urgent calibration in high workload facilities via diagnostic reference per unit to establish an institutional local standard. Parameters involved in this research are X-ray tube output (mGy/mAs), workload (mAmin/ week), use factor and fluence (mGy/cm2). Comparative studies were done at two local hospitals in Guyana namely Georgetown Public Hospital Corporation (GPHC) and Linden Hospital Corporation (LHC). Barium meals (B.M) and intravenous pyelograms (IVP) were measured at Georgetown Public Hospital Corporation. The RaySafe X2 was placed in the path of the X-ray beam at different settings of peak kilovoltage and millamperage- second and the radiation quantities were displayed on the base unit. This research investigated the effect of variation factor on the calibration of the static radiography on a fluoroscopy unit. Factors measured included kerma, tube output, fluence and age of tube output and workload. The differences obtained were significant in the cases of the elevated R/F sensor at 60 cm and at table top of 115 cm and varying peak kilovoltages and milliamperage. The difference in tube output could be attributed to anode surface damage (pitting), age of the tube, filtration, and collimation. A lower workload requires less calibration. In conclusion facilities with a workload of approximately 50 patients do not require more frequent calibration.