최신 Multi-detector CT와 64 Multi-detector CT의 장비사별 선량비교: Filtered Back Projection과 Iterative Reconstruction 영상

• 영문명: Radiation Dose Reduction by Filtered Back Projection and different Iterative Reconstruction algorithms: Comparison between up-to-date and 64 section CT Scanners
• 발행기관: 대한CT영상기술학회
• 저자명: 김완역(Wan Youk Kim) 김문찬(Moon Chan Kim) 장광현(Kwan Hyun Chang)
• 간행물 정보: 『대한CT영상기술학회지』대한전산화단층기술학회지 제15권 제1호, 47~54쪽, 전체 8쪽
• 주제분류: 의약학 > 방사선과학
• 파일형태: PDF
• 발행일자: 2013.04.30

국문 초록

목적 최신장비와 64 MDCT 장비의 선량 감소효과를 noise를 이용하여 기존의 재구성 방법인 Filtered Back Projection(FBP)과 영상반복재구성(Iterative Reconstruction)을 이용하여 단계별 변화에 따른 각 장비 및 회사별 선량 감소 효과를 평가하고자 하였다. 대상 및 방법 장비는 GE사의 Discovery 750, LightSpeed VCT, Philips사의 Brilliance iCT, Brilliance 64, Siemens사의 Somatom Definition Flash(dual), Somatom Definition AS(single), Toshiba사의 Aquilion 640, Aquilion 64 장치를 비교 사용하였다. 고정 Effective mAs는 각 병원 흉부 protocol을 이용하여 AEC 적용 후 Ramdo phadom을 scan하여 가장 높은 선량을 고정 Effective mAs로 선택하였고 noise 검사는 ACR phantom을 사용하였으며 고정 Effective mAs를 변화시키며 검사하여 근접한 noise값이 나올 때까지 반복 검사하였다. ImageJ 프로그램을 이용하여 noise값을 측정하였으며, Effective mAs와 CTDIvol를 비교하였다. 결과 GE사의 Discovery 750, ASIR(Adaptive Statistical Iterative Dose Reconstruction)에서는 FBP에서 9%, ASIR 적용 시 25%, 42%, 60%, 73% 선량 감소, Philips사의 Brilliance iCT, iDose 1, 2, 3, 4, 5에서는 FBP에서 17%, iDose 적용시 29%, 34%, 42%, 50%, 60%, 68% 선량 감소, Siemens사의 Somatom Definition Flash, SAFIR 1, 2, 3, 4, 5에서는 FBP에서 10%, SAFIR 적용 시 20%, 31%, 50%, 62%, 71% 선량 감소, Toshiba 사의 Aquilion 640, AIDR(Adaptive Iterative Dose Reduction), MILD(50%), STD(75%), STR(75%)에서는, FBP에서 12%, AIDR 적용 시 34%, 50%, 65% 선량 감소 효과가 있었다. 결론 최신의 MDCT 장비는 회사별로 조금은 차이가 있지만 64 MDCT에 비해 FBP영상에서 선량 감소효과는 있었으며, IR영상 또한 기존의 FBP영상보다 선량 감소효과가 높은 것으로 측정되었다. 검사 부위별 적절한 IR 단계를 지정하여 검사하고 이를 임상 판독의사가 이용한다면 기존의 FBP보다 선량 감소효과가 높아 환자 선량감소에 도움이 될거라 사료된다.

영문 초록

Ⅰ. Purpose Iterative reconstruction (IR) algorithms are commercialized and it promising for further reduction of patient exposure in computed tomography (CT). However their detailed algorithms and dose reducing powers may be variable between manufacturers. Thus the purpose of this study was to analysis the effect of radiation dose reduction by IR in CT scanners of four major CT systems. Ⅱ. Meterial and Methods Effective mAs and CTDIVOL were measured on the filtered back projection (FBP) and three level (low, median, maximum) of IR in up-to date and 64 section CT scanner in each manufacturers; Discovery 750 vs. LightSpeed VCT (GE healthcare, USA), Brilliance iCT vs. Brilliance 64 (Philips Medical System, Netherlands), Somatom Definition Flash vs. Somatom Definition AS (Siemens Healthcare, Germany), and Aquilion 640 vs. Aquilion 64 (Toshiba Medical System, Japan). These data were obtained by using RANDO phantom at the same noise level under 120 kV in each manufacturer. Noise was evaluated using ACR phantom and ImageJ (NIH, USA). Data were analyzed and compared in each manufacturer using analysis of variance. Ⅲ. Result In up-to-date CT scanners compared with 64 section scanners, the decrease rate of effective mAs in ‘P’, ‘S’, ‘G’ and ‘D’ manufacturers were 15%, 2%, 17%, and 5% with FBP; 40%, 45%, 47%, and 29% with low level of IR; 59%, 58%, 63%, and 43% with median level; 67%, 68%, 76%, and 60% in maximum level. The decrease rate of CTDIVOL were 17%, 20%, 9%, and 12% with FBP; 42%, 50%, 42%, and 34% with low level; 60%, 62%, 60%, and 50% with median level; 68%, 71%, 73%, and 65% with maximum level of IR. Ⅳ. Conclusions Even with FBP, up-to-date CT scanners provide the decrease of about 10% in radiation dose than conventional 64 section scanners. While there are differences in the ability of IR between manufacturers, higher level of IR reveals the more effective reduction of radiation dose.

목차

Abstract

Ⅰ. 서론

Ⅱ. 대상 및 방법

Ⅲ. 결과

Ⅳ. 고찰

Ⅴ. 결론

참고문헌

국문초록

키워드

Iterative reconstruction filtered back projection effective mAs CTDIVOL