Estimation of entrance skin dose (ESD) and exit dose (ED) in abdominal radiography using nanoDot optically stimulated luminescence dosimeter (OSLD)

• Main Authors: Sayed, Inayatullah Shah, Roslan, Nurul Shuhada, Abdul Majid, Zafri Azran
• Format: Conference or Workshop Item
• Language: English; English
• Published: 2019
• Subjects: QC Physics
• Online Access: http://irep.iium.edu.my/77657/1/ISMP2019_paper_32_Revised_Abstract.pdf; http://irep.iium.edu.my/77657/2/ISMP%202019%20_Latest.pdf; http://irep.iium.edu.my/77657/

It is essential to monitor patient’s dose to ensure the proper implementation and practices of radiation protection in diagnostic X-ray imaging and to reduce the risks of radiation exposures. Our study aimed to estimate the entrance skin dose and exit dose in abdominal radiography using nanoDot OSLD. Siemens Multix Top X-ray system was used. Kyoto Kagaku PBU-50 phantom (Torso) was scanned. The phantom was placed on the table bucky in antero-posterior supine position. The source-to-image distance was set at 110 cm. A nanoDot OSLD was placed at the surface of abdomen near umbilicus which was exposed to central ray of the X-ray beam to measure the ESD. Exit dose was measured by positioning another nanoDot OSLD exactly opposite (underneath the phantom) to nanoDot OSLD that was used for measurement of ESD. After exposing the phantom with three exposures (70 kVp and 20 mAs, 75 kVp and 25 mAs & 81 kVp and 28 mAs) with table bucky the phantom was exposed without table with the same kVp and mAs. The ESD and ED with table bucky were higher than those without table for each exposure. The measured ESD ranged from 1.38 mGy to 2.44 mGy while exit dose ranged from 0.036 mGy to 0.080 mGy. The ESD and ED with table bucky and without patient table increased as the kVp and mAs increased. The ESD and ED with table bucky was higher than that without patient table for each exposure. Higher ED values with table bucky indicated the contribution of backscattered radiation produced by the patient table. It is concluded that, the OSLD provided the comparable dose results with the published data. The Linear No-Threshold (LNT) model describes that the smallest amount of radiation dose is unsafe for human health and increases the risk of cancer. Thus, patients need to be protected from unnecessary radiation dose contributed by backscattered X-ray photons induced by the patient table.