Quality assurance and radiation safety assessment of diagnostic X-Ray units

Abstract

Important radiographic parameters which affect diagnostic image quality have bccn inv,estigated taking data from different diagnostic X-ray installations in Dhaka city. Investigations have been carried out according to a quality control protocol and the measured parameter values are compared to the relevant acceptance limits. In this work, Congruence between optical and radiation fields are investigated and found that 77.5% are within hmit. On the other hand, 22.5% are found to be out of limit. More than half of the installations (60%) are within the beam alignment limit. For most of the installations (92.5%) nominal focal spot size of diagnostic X-ray machines are matched perfectly with the rating of focal spot size, Film-screcn contacts are checked in the work to impro,-e image quality and 65% installations are found to have the expected uniformity_ While investigating half value layers (HVL) and hence X-ray beam quality it is found that none of the diagnostic X-ray installations can achieve the recommended levels for beam quality. pH value, temperature, time and room temperature for developing and fixing liquid are investigated in order to eliminate improper film processing techniques. View-box condition and ambient light level of view-box room are checked to obtain accurate information about treatment. A large variation is observed in average view-box illumination for different diagnostic X-ray installations and about one-third view-boxes only are found to be within the percentage uniformity limit. The ambient light level of the view-box rooms is comparatively better ~ 92.5% are found to obcy this observation. General information about intensifying screen, radiography and mammography film is also collected_ X-ray tube voltage, output radiation dose and exposure time for diagnosllc X-ray machines are tested to achieve significant dose reduction without loss of diagnosllc inf0rmation. It is found that output radiation dose varies in different diagnostic X-ray installations. It is also found that 70% X-ray installations achieve the recommended value for tube voltage while 87.5% measure the exposure time appropriately. Radiation dose level at patient wailing room, dark room and around control panel is investigated. About 92.5%,85% and 77.5% installations show their results within the acceptance limit at these positions respe<:tively which provide radiation safety for patients, workers and public in diagnostic radiology. On the basis of this work, the results could be utilized in order to improve radiographic image quality with reduction of radiation dose in diagnostic X-ray facilities.