Pediatrik Hastalarda Yüksek Pitch Kullanılarak Bilgisayarlı Tomografi Çekilmesinin Radyasyon Dozu Üzerine Etkisi

Abstract

High pitch Computed Tomography effect on radiation dose in pediatric patients, Hacettepe University Faculty of Medicine, Thesis in Radiology, Ankara, 2013. The aim of this study is to assess radiation dose reduction and image quality with high-pitch dual source CT in comparison with standard pitch with pediatric thorax and abdominal CT. Between Janunary 2012 and June 2013, a total of 192 patients (median age 65,2 months) underwent high pitch thorax CT and 142 patients (median age 52 months) underwent high pitch abdominal CT in this study. High-pitch (value:3) mode CT was performed with 64-slice DSCT. This was compared to a group of 57 patients (median age 74,6 months) who underwent standard thorax CT (pitch: <1.5) and a group of 54 patients (median age 54,2 months) who underwent standard abdominal CT (pitch: <1.5). Scanning protocols were adjusted for clinical indication and patient weight in both groups. At aortic valve in thorax and at the umbilical level in abdomen anteroposterior (APD) and lateral (LD) diameters was measured in all patients and effective diameter (ED) was calculated. Scan time (ST) and length (SL), qualitative (subjective noise, diagnostic confidence and artifacts related to patient, respiratory,cardiac or bowel movement) and quantitative (density measurements from: descending aorta, muscles around shoulder and outside of thorax in thorax; liver, abdominal aorta, psoas muscle and outside of abdominal wall in abdomen) assessment, CTDIvol, DLP, size specific dose estimate (SSDE, calculated by using conversion factors given by AAPM at report no: 204) were assessed in both groups. Comparisons were made by using chi-square test, independent sample t test and Mann-Whitney U test. Both patient groups at thorax CT were similar with respect to age, APD, LD and ED. Mean ST of high-pitch thorax CT was 1.19 s, while it was 7,09 s in standard pitch mode CT. In comparison with standard pitch mode, high pitch mode of DSCT reduced radiation exposure by 50% (SSDE according to ED 1,94 and 4,16 mGy). CTDlvol, DLP and SSDE parameters were significantly lower in high pitch mode (p<0.001). Subjective noise on high pitch thoracic imaging did not have any effect on diagnostic confidence and quantitative measures were similar among both types of imaging. Less artifacts, either related to patient movement, cardiac or respiratory were observed with high pitch imaging (p<0.001). Both patient groups at abdominal CT were similar with respect to age, APD, LD, ED and SL. Mean ST of high-pitch abdominal CT was 1.59 s, while it was 10,9 s in standard pitch mode CT. In comparison with standard pitch mode, high pitch mode of DSCT reduced radiation exposure by 60% (size specific dose estimatation according to ED 1,86 and 4,74 mGy). CTDlvol, DLP and SSDE parameters were significantly lower in high pitch mode (p<0.001). Subjective noise on high pitch abdominal imaging did not have any effect on diagnostic confidence and quantitative measures were different among both types of imaging. Less artifacts, either related to patient or bowel movement were observed with high pitch imaging (p<0.001). The use of high pitch DSCT at thoracic and abdominal pediatric imaging significantly decreases scan times and radiation exposure when compared to standard CT.