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Title: Dose optimization in pelvic radiography by air gap method on CR and DR systems - A phantom study
Authors: Chan, CTP
Fung, KKL 
Keywords: Air gap method
Dose optimization
Issue Date: 2015
Publisher: W.B. Saunders
Source: Radiography, 2015, v. 21, no. 3, p. 214-223 How to cite?
Journal: Radiography 
Abstract: Objectives: This study aimed at investigating the feasibility of replacing the anti-scatter grid with an air gap at a pelvic radiographic examination in order to reduce patient dose while retaining diagnostic image quality. Methods: An anthropomorphic pelvis phantom was placed on a device that allowed the adjustment of different air gap thicknesses introduced between the phantom and the image receptor of Computed Radiography (CR) and Digital Radiography (DR) systems. Grid and non-grid images with different air gap thicknesses of both systems were produced. Ovary and testes doses were measured using thermoluminescent dosimeters. Radiographic quality of all images was rated by 5 experienced radiographers blindly using the Image Quality Score (IQS) and Visual Grading Analysis (VGA) systems. Results: Images of diagnostic quality were produced while the grid was replaced by a range of 0-25cm air gap thickness in the pelvic radiographic examination. At non-grid examination with 10cm air gap thickness, a maximum of relative dose reduction by 70.7% and 81.6% at CR; 68.6% and 79.4% at DR were achieved respectively at ovary and testes locations of the phantom as compared with their corresponding grid examinations. Conclusion: 10cm was found to be the optimal air gap thickness at the tested pelvic examination. Effective dose was found to be reduced by 2 and 2.3 times respectively at the CR and DR examinations while the anti-scatter grid was replaced by 10cm air gap. However, dose reduction effect by air gap method was found to be more pronounced in CR than in DR.
ISSN: 1078-8174
DOI: 10.1016/j.radi.2014.11.005
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