Some experiences from radiation protection of patients undergoing X-ray examinations in Tanzania

A study of patient entrance surface dose (ESD) received by adult patients was undertaken in five major diagnostic facilities in Tanzania. Five selected X-ray projections for chest PA; abdomen AP; lumbar spine AP; lumbar spine LAT and pelvis AP were done in the study. The mean ESDs after introduction of dose reduction methods were 0.34 mGy, 5.41 mGy, 3.7 mGy, 4.8 mGy and 8.8 mGy for chest PA; abdomen AP; pelvis AP; lumbar spine AP and lumbar spine LAT, respectively. The variations of doses observed in the study were influenced by performance characteristic of X-ray equipment, patient shape and size, type of image receptor, radiographic techniques as well as skills employed. The results show that increasing the tube voltage reduced the ESD by 35.5%, while lowering of mAs reduced ESD in the range from 15% to 60%. The reduction of ESD by increasing the filtration ranged from 11% to 58% while increasing of speed class of film-screen combination reduced the ESD in the range from 33% to 57%. The corresponding results of image quality show that out of 1064 scores of image criteria 298,481 and 285 were rated for good, satisfactory and poor respectively. The results of this study provide an evidence of existing potential for dose reduction in the diagnostic radiology facilities and the most important factor for improvement is to increase awareness, both from reality of harm from unnecessary radiation exposure and with relative ease doses can be reduced. The study should therefore be implemented on the national scale as an approach to establish guidance levels of patient entrance surface dose for good medical practice and regular monitoring purposes. (author)