Cone beam CT quality assure procedure and the analysis of results / 中华放射肿瘤学杂志

ABSTRACT

Objective To study the image quality control system to ensure that equipment meet clinical needs.Methods It was scanning the Catphan504 phantom with models of high quality head,standard dose head and pelvis,we could get the results of CT numbers linearity,uniformity,spatial resolution,contrast resolution.Using T test to compare different scanning technique results.Results The standard dose head scanning technique was better than the pelvis scanning technique in CT numbers linearity test,and gets the best result in uniformity test.The result of CT numbers uniformity was higher in the standard dose head scanning than the high quality head and the pelvis scanning (9.7 ±3.9 vs.17.9 ±5.3,P =0.00 and 9.5 ± 4.0 vs.31.1 ± 5.7,P =0.00).The result of contrast resolution was higher in the pelvis scanning than the high quality head and the pelvis scanning (5.6 ± 0.1 vs.1.3 ± 0.5,P =0.00 and 6.0 ± 1.0 vs.1.3 ± 0.5,P =0.00).The result of spatial linear distance was very accurate,the range was 4.98 -5.06 cm.Conclusions The results of spatial linearity test are stable and accuracy,but CT numbers linearity and uniformity test are affected by the scanning technique significantly for device.To spatial resolution test and contrast resolution test,we need to set the standard and tolerance according to each linear accelerator specialty.