The impact of increasing SID on patient dose in pa abdomen imaging

Transcription

1 The impact of increasing SID on patient dose in pa abdomen imaging Poster No.: C-1074 Congress: ECR 2016 Type: Authors: Keywords: DOI: Scientific Exhibit T. Starc 1, N. Mekis 2 ; 1 Brezovica/SI, 2 Ljubljana/SI Radioprotection / Radiation dose, Abdomen, Digital radiography, Radiation safety, Dosimetric comparison /ecr2016/C-1074 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 6

2 Aims and objectives One of the most important key roles of radiographer's work is optimisation, a way to reduce the dose received by patient and at the same time maintain the image quality. Increase of Source to Image receptor Distance (SID) is one way of possible dose reduction [2-5] as x-ray beam intensity decreases with the square of the distance from the source. In this study we measured the entrance surface dose (ESD) and the dose area product (DAP) to the phantom in postero-anterior (PA) plain abdominal imaging, when (SID) was increased. Methods and materials The measurements were carried out on a conventional x-ray unit on a standing Bucky with grid specifications of r=13:1, n=70; f 0= 150 cm and with CR plates dimensions of cm. The patient was simulated by a whole body phantom PBU 60. The measurements were performed in PA projection and the positioning was carried out according to the literature. The exposure parameters were consistent throughout the whole study, with 79 kv and AEC with central chamber selected, according to the European guidelines. The ESD and DAP were measured at SID 115cm, 150 cm and 180 cm. An electronic dosimeter PDS from Unfors was used for ESD measurements, including backscatter, and a DAP meter from IBA dosimetry was used for DAP measurements. Each image acquisition was repeated three times and an average was recorded. The image evaluation was done according to European criteria. Results In ESD measurements, with SID between 115 cm and 150 cm, we found a statistically significant dose reduction of 21% (p<10-3 ) and also a dose reduction of 24% with SID between 115 cm and 180 cm (p<10-3 ). No statistically significant difference was found with SID between 150 cm and 180 cm. No statistically significant difference was found regarding the image quality. For DAP measurements no statistically significant difference was found between all three SIDs. With increased SID from 115 cm to 150 cm, higher exposure factors are needed to obtain the same image density. Due to higher exposure factors one could expect higher ESD, however the x-ray beam intensity decreases with the square of the distance from the source, so the ESD decreases even though the exposure factors were higher. Page 2 of 6

3 Images for this section: Fig. 1: Native abdominal image form the study - Ljubljana/SI Page 3 of 6

4 Fig. 3: Boxplot of DAP values in relation to different SID - Ljubljana/SI Page 4 of 6

5 Fig. 2: Boxplot of ESD values in relation to different SID - Ljubljana/SI Page 5 of 6

6 Conclusion Based on this phantom study we can conclude that the best SID for plain abdominal imaging in PA projection is 150 or 180 cm, with no loss of image quality. Personal information References 1. European Commission. Council directive 97/43/Euratom on health protection of individuals against the dangers of ionizing radiation in relation to medical xposure, and repealing directive 84/466/Euratom. Off J Eur Communities 1997; L180 (40): Tugwell J, Everton C, Kingma A, Oomkens D M et al. (2014. The College of Radiographers: Elsevier 3. Mekiš N, Starc T (2012). Pove#ana razdalja goriš#e-slikovni sprejemnik zmanjša vstopno kožno dozo. Analogna in digitalna radiološka tehnologija : zbornik predavanj in povzetkov posterjev kongresa Društva radioloških inženirjev Slovenije, Ankaran, 18. in 19. maj Ljubljana: Društvo radioloških inženirjev Slovenije, 2012, str. 84. McDonnell S, O'Leary D (2004). Increasing film-focus distance (FFD) reduces Radiation dose for x-ray examinations. Radiation protection dosimetry 108 (3), Brennan PC, Nash M (1998). Increasing FFD: An effective dose-reducing tool for lateral lumbar spine investigations. Radiography 4 (4), Page 6 of 6