Multi-detector CT장치의 저대조도분해능 평가

• 영문명: Estimation of Low Contrast Resolution in Multi-detector CT: Comparison of CATPHAN, ACR Phantom and AAPM Phantom
• 발행기관: 대한CT영상기술학회
• 저자명: 김지혜(Ji Hye Kim) 김문찬(Moon Chan Kim) 남윤철(Yoon Cheul Nam)
• 간행물 정보: 『대한CT영상기술학회지』대한전산화단층기술학회지 제11권 제1호, 120~126쪽, 전체 7쪽
• 주제분류: 의약학 > 방사선과학
• 파일형태: PDF
• 발행일자: 2009.09.30

영문 초록

Purpose As the quality control is getting more important, it is required to maintain the improved image quality consistently. Especially, low contrast resolution is ability to detect low contrast lesion which shows in detail CT number difference like abdominal organs in MDCT. Therefore, the purpose of the study was comparison of CNR and visual evaluation, between the estimation of low contrast resolution of MDCT from each manufacturers and the estimation of low contrast resolution by each different phantoms by using phantoms in CT that have become commercial. Materials and methods We used LightSpeed VCT(GE medical system, USA), Aquilion 64(Toshiba medical system, Japan), Brilliance 40(Philips medical system, Netherlands) in Samsung medical center. We also used CATPHAN, ACR phantom and AAPM phantom for low contrast resolution phantom. Each of CATPHAN and ACR phantom has surrounding substances and holes those difference of attenuation coefficient are 5HU and 6HU, We measured AAPM phantom by filling holes to make 6HU difference with solution mixed saline solution and contrast media. In phantom study, We performed axial scan mode and 5mm slice thickness for 15mGy of CTDIvol that is applied to abdominal study(GE MDCT’s condition was 120kVp, 170mAs, Philips was 120kVp, 210mAs, Toshiba was 120kVp, 160mAs). For the estimation, We calculated contrast noise ratio(CNR) of materials’ CT number and CT number and noise on background by using ROI in three different phantoms. We observed scan images by using PACS system from GE medical center which was in limiting ranges window width 100-230HU and level 80-180HU, then we estimated low contrast resolution by using diameter which shows minimum dimension that could be seen visually. There were 5 CT special radiologic technologists to raise objectivity and the diameters that are distinguished by over 4 of them were choosen and reflected to result it. Results When low contrast resolution of MDCT from each manufacturer is estimated by CNR, the values of them from each manufacturer which are GE’s, Philips’s and Toshiba’s were 1.00, 0.93, 0.79 in CATPHAN phantom, 1.05, 0.97, 0.88 in ACR phantom and 0.92, 0.85, 0.81 in AAPM phantom. for visual evaluation, It was able to distinguish diameter of 3mm in GE’s and Philips’s, 4mm in Toshiba’s by CATPHAN phantom; 3mm in GE’s, 4mm in Philips’s Toshiba’s by AAPM phantom. When low contrast resolution by each different phantom is estimated by CNR, the values of them from each phantom which are CATPHAN, ACR and AAPM phantom were 1.00, 1.05, 0.92 in GE’s, 0.93, 0.97, 0.85 in Philips’s, 0.70, 0.88, 0.81 in Toshiba’s. It was able to distinguish diameter of 3mm in CATPHAN and ACR phantom, and 3.2 mm in AAPM phantom by GE’s; 3mm in CATPHAN, 4mm in ACR phantom and 6.4mm in AAPM phantom by Philips’s; 4mm in CATPHAN and ACR phantom, and 6.4mm in AAPM phantom by Toshiba’s. Conclusion When low contrast resolution of MDCT from each manufacturer is estimated, CNR of GE’s was the highest and it was able to distinguish the smallest whole in all phantoms. As the values show, GE’s was the best and then Philips’s. However, compare to those, Toshiba’s had the lowest CNR in all phantoms also it was restrictive to distinguish the smallest whole by sight. When low contrast resolution of three phantoms was estimated, CNR of CATPHAN and ACR phantom was the highest. CATPHAN phantom is the idealist phantoms to estimate low contrast resolution because of various diameters and attenuation coefficient. ACR phantom has variety of gap between diameters of wholes, but it was restrictive on distinguishing microscopic dimensions on scan images. AAPM phantom was not suited to measure low contrast resolution because the gap of holes is not closed each other and the lowest CNR values in MDCT.

목차

Abstract

Ⅰ. 목적

Ⅱ. 대상 및 방법

Ⅲ. 결과

Ⅳ. 고찰

Ⅴ. 결론

참고문헌

키워드

low contrast resolution phantoms phantom image evaluation