Evaluation of conventional x-ray diagnostic equipment and radiological protection systems of hospitals and clinics installed in Recife city, Brazil

Diagnostic radiology is the main contributor to the man-made exposure of general population. Since Quality Assurance (QA) programs ensure high quality diagnostic images with the lowest possible radiation dose to the patient, it has been recommended that all introduce QA programs for their radiological facilities. Consequently it is important to check the adequacy of equipment operating parameters in diagnostic radiography facilities, to ensure that a high quality of service is delivered. The purpose of this study was to evaluate the operating conditions of diagnostic units installed in Recife, Pernambuco. The study included 31 X-ray units from both public and private diagnostic services. The following parameters were evaluated: coincidence between the luminous and radiation fields; alignment of the radiation beam; agreement between the real and preset values of kVp and exposure time; filtration; half value lower (HVL); luminance of the view box; uniformity of the luminance; illuminance of the environment. The results showed that 20% of the equipment surveyed exhibited discrepancies between the luminous and radiation fields greater than 2% of the source to skin distance. The test of kilovoltage showed that 48% of the units do not fulfill the acceptability criteria, presenting discrepancies higher than ± 10% between the measured and preset values. The results of the accuracy of the timer indicated that 81% of the equipment surveyed present a discrepancy greater than ± 10% between the time selected in the control panel and actual exposure time.The test of the filtration shown that, in 20% of the equipment, this was inferior to 2,5 mm Al. The test of the luminance of view box shown that 96% of the equipment, shown a luminance lower of 2.000 cd/m2. Related to the test of the uniformity of the luminance, 81 % of the equipment shown a variation of the uniformity higher then 10%. The test of the iluminancy of the environment shown that 61 % of the equipment presented on iluminancy level out of the gap between 50 and 100 lux. The results of this survey showed that a high percentage of the equipment surveyed demonstrated inadequate operating conditions, reinforcing the need to implement quality control protocols in conventional x-ray units located in Recife. (author)