CT Guided Interventional Sturdy에서 Conventional Scan Mode 적용에 따른 선량 감소에 관한 연구

The Sturdy for Reduction of Radiation Dose According to Conventional Scan Mode in CT Guided lnterventional Sturdy

Purpose Recently CT guided interventional sturdy applied the helical scan mode which occurred overscanning dose. If you apply conventional scan mode, overscanning dose can be reduced. This sturdy intend to evaluate dose reduction and image quality from applying the protocol in conventional scan mode that decrease overscanning dose. Materials and methods All exams were proceeded on Aquilion 64 of Toshiba and used for ACR and CATPHAN phantom. the average number of pre. San was 1.0±0, scan range was an average of 9.2±2.6 cm in CT guided bone biopsy. the average number of pre. scan was 3.0±1.1, scan range lesion average of 11.1±3.3 cm in CT guided kidney RFA. we scanned repeatedly lesion area inserting the needle into the organ except for pre. scan. 7.2+3.2 times in CT guided bone biopsy, 14.0±5.1 times in CT guided kidney RFA. The conditions of helical scan mode protocol were as followed: 120 kVp, 70 mA, 0.6 sec, 2 mm slice thickness, 8 mm beam collimation, 0.938 pitch, and effective mAs was 45 mAs. to apply same CTDIvol with helical scan mode, the conditions of conventional scan mode were set on 120 kVp, 80 mA, 0.6 sec, 2 mm slice thickness, 8 mm beam collimation. We estimated the effect of dose reduction from effective dose derived from total DLP of conventional scan mode and thar of helical scan mode. ACR and CATVHAN phantom were used for evaluation of image quality. Results The estimate of dose showed total DPL 174.2±51.8 mGyㆍcm, effective dose 3.3±0.9 mSv in conventional scan mode, compared with total DPL 256.6±82.3 mGyㆍcm, effective dose 4.9±1.6 mSv in helical scan mode, which is reduced in 32.1±3.9% in CT guided bone biopsy. In CT guided kidney RFA, total DPL 465.3±139.7 mGyㆍcm, effective dose 7.0±2.0 mSv in conventional scan mode, compared with total DPL 647.5±200.6 mGyㆍcm, effective dose 9.7±3.0 mSv in helical scan mod, which is reduced in 29.1±6.8%. The result of noise is 15.4 HU in helical scan mode and 21.9 HU in conventional scan mode which is 6.5 HU higher d1an helical scan mode but almost did nor affect the image quality. Conclusion Accordingly, in conventional scan mode the ration of dose reduction was approximately 29.1~32.1% clue to decreased overscanning dose and the risk of stochastic effects and deterministic effects was not found in CT guided interventional sturdy. Therefore, we should sturdy more minimize dose for the patient while maintaining image quality through using optimal protocol.