복부CT에서 면적에 따른 CTDI와 유효선량 및 SNR의 비교 연구
A Comparative Study of CTDI and the Effective Dose and the SNR according to the Area in the Abdominal CT
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복부CT에서 면적을 산출하여 CTDI (computed tomography dose index) 변화에 따른 유효선량 및 SNR (signal to noise ratio)을 비교함으로써 진단적 가치가 높은 영상을 얻는 동시에 환자가 받는 피폭 선량 감소를 목적으로 한다. 복부CT 검사 환자 60명을 400-499 cm2 (12명), 500-599 cm2 (21명), 600-699 cm2 (17명), 700-799 cm2 (9명) 4그룹으로 나누었다. 복부CT 데이터를 ImageJ 프로그램을 이용하여 환자의 면적을 산출하였고, CTDI, DLP, SNR 및 유효선량을 계산하였다. 복부면적이 증가할수록 CTDI는 7.3 mGy에서 13 mGy로 증가였고, DLP는 394.4 mGy･cm에서 732로, 유효선량에서도 5.9 mSv가 11mSv로 증가하였다. SNR은 12.7에서 15 dB을 유지하였다. 복부면적에 따른 CTDI의 평균은 8.9 mGy, DLP의 평균은 481.5 mGy･cm, 유효선량은 7.2 mSV로 산출되었다. 복부하중계수에 DLP를 곱하여 산출한 유효선량은 통계적의로 유의한 차이가 없었고 (p < .05), SNR에서는 유의한 차이가 있었다(p > .05). 복부CT 영상검사에서 영상의 질 향상을 위해서는 환자의 면적에 따른 CTDI를 고려하여 환자의 피폭선량을 감소시킬 수 있어야 한다.
Abstract
To obtain the best SNR (signal to noise ratio) due to changes in CTDI (computed tomography dose index) made for the purpose of setting the optimum image obtained by reducing the dose in abdominal CT. Abdominal CT scans of 59 patients a 400-499 cm2 (n = 12), 500-599 cm2 (n = 21), 600-699 cm2 (n = 17), 700-799 cm2 (n = 9) were separated by four groups and the effective dose was used in the Excel to get the area of the patient using the ImageJ program. Patients of CTDI, DLP, SNR, the effective dose were analyzed. Abdominal CT area was increased to 13 mGy in CTDI is 7.3 mGy, DLP to 732 in 394.4 mGy･cm, also effec-tive dose was 5.9 mSv increase in 11mSv. SNR is 15 dB was maintained at 12.7. CTDI according to the aver-age of the abdominal area of 8.9 mGy, the average of the DLP was 481.5 mGy･cm, the effective dose is cal-culated to be 7.2 mSV. Effective dose was calculated by multiplying the load factor of DLP in the abdomen showed no statistically significant difference of (p < .05), there was a significant difference in SNR (p > .05). To improve image quality of abdominal CT scan image in consideration of the CTDI according to the volume of the patient it should be able to reduce the radiation exposure of the patients.
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