Patient size-specific models for tube load selection during diagnostic examination of patient trunk

Abstract

Each time a radiograph is to be produced a set of exposure parameters such as tube load (mAs-product of tube current and exposure time), tube potential (kV), focus to skin distance (FSD) are selected such that it produces optimal image required for diagnosis. The choice of exposure parameters depend on the nature and part of the body to be examined- its thickness, density and pathology. Therefore, optimal exposure is required to obtain adequate diagnostic information at the same time conforming to the principle of optimisation. Exposure parameter selection during conventional radiography is largely donebased on the discretion of the Radiographers, except where digital technology (facility equipped with automatic exposure control-AEC) is available. This practice has resulted in the production of low quality image and error in diagnosis. However, in order to select appropriate technical parameters, it is essential to understand the anatomical composition of a patient during diagnostic examination. This study demonstrates models for determining patient thicknesses (trunk area) using patient weight. And it also describes the application of the model obtained in the selection of tube load during diagnostic examination. Software based on National Radiological Protection Board (NRPB) optimal tube loads was developed to execute the simple model for adult patient trunk. Results obtained were compared with the tube load values used during the real time examinations.