Determination of Entrance Skin Dose Arising from Conventional X-Ray Examinations in 15 Radiological Centers by Thermoluminescent Dosimeters

Nowadays, medical imaging plays an important role in the health care systems around the world. Diagnostic radiology is still a fundamental technique by providing valuable services to the society. Undoubtedly diagnostic radiology is by far the largest contributor of radiation dose to the society as a whole from the man made sources. The national radiation protection board (NRPB) introduced the use of diagnostic reference levels (DRLs) as an efficient standard for optimizing the radiation protection of patients. The physical parameter recommended for monitoring the (DRLs) in conventional radiography was the entrance skin dose (ESD) and methods for measuring it were clearly described in NRPB standard protocol. In this study, the dose measurements were carried out in 15 radiological centers. The data were colleted for 1183 radiographs of adult patients. The sample of patients was chosen so that the weight of the patients was in the range of 40-107 kg. A total of eight typical x-ray examinations were chosen for the study. The entrance surface dose (ESD) was directly measured by thermoluminescence dosimeters (TLDs). The average skin dose (mGy) of patients arising from x-ray examinations included in this study are as following:Chest PA- 0.34, chest Lat- 0.82, lumbar spine AP- 2.76, lumbar spine PA- 5.2, pelvis AP- 1.9, abdomen AP- 2.1, skull PA- 1.78, skull Lat- 0.96.Discussion and So far the national DRLs for Iran have not been reported. Therefore, our results were compared against those reported by NRPB for UK. It is evident that the average ESDs obtained in this work for abdomen AP, pelvis AP, lumbar AP and lumbar Lat examination do not exceed DRLs values worked out by NRPB. On the contrary for chest PA, chest Lat, skull PA and skull the ESD acquired in this study was higher in comparison with the DRLs suggested by NRPB. The differences are related to different film screen speeds and techniques used in the radiological departments included in these two studies. With respect to the role of radiographic parameters on the patient dose, it is possible to optimize these parameters to maintain the image quality while reducing patient dose.