최근 PET/CT가 급격하게 증가하면서 의료기관 사이에 영상의 이동도 증가하고 있다. 이에 서로 다른 의료기관 간의 시스템 별 표준섭취계수 차이를 반영하기 위하여 1 Bed에서 표준섭취계수, 슬라이스 내의 표준섭취계수 변화율과 측정시간에 따른 표준섭취계수를 정량적으로 비교할 수 있는 팬텀을 이용한 비교측정이 필요하다. 본 연구에서는 임상에서 사용하는 다양한 PET/CT 시스템의 표준섭취계수 차이에 대한 연구를 통하여, PET/CT 영상의 표준화섭취계수의 신뢰성을 확보하고자 하였다. 대한민국 전국에 분포되어 의료기관에 설치된 PET/CT 장비 10대를 대상으로 하였으므로, 정확한 방사능 산출을 위하여, 한국표준과학원의 검출기로 검증을 통하여 실험하였다. NEMA PET$Phantom^{TM}$의 내부구조물을 제거하고 $^{18}F$-FDG 1 mCi를 6,000 mL 증류수에 균일하고 분포하도록 마그네틱 스터러와 마그네틱 바의 회전력으로 희석하여, 팬텀에 주입하였다. 주입 후 60분, 70분, 80분, 90분, 100분, 110분, 120분에 3분간 영상을 획득하고, 관심영역 $200\;cm^2$에 대하여 분석하였으며, 유용성 확인을 위하여 임상환자를 대상으로 교정표를 산출하였다. 1 Bed에서 표준섭취계수, 슬라이스 내의 표준섭취계수 변화율, 측정시간에 따른 표준 섭취계수 변화율과 함께 표준섭취계수의 변이계수가 -11.0~9.90%로 국제적으로 통용되는 기준인 ${\pm}10%$를 1개의 장비를 제외하고 모두 만족하였다. 또한, 시스템 별 평균 표준섭쉬계수 차이를 이용하여 0.803~1.246으로 이루어진 교정표를 도출하였고, 정상인을 통한 임상 적용에서 선형회귀분석을 통하여 유의함을 확인하였다. 본 연구를 통하여 PET/CT 장비간의 표준섭취계수 차이를 교정표를 이용하여 정량적으로 비교할 있는 근거를 제시한다면 정확한 진단에 도움이 되며, 아울러 이에 대한 세계적 기준이 명확하지 않기에 유사 연구에 도움이 되리라 사료된다.
최근 PET/CT가 급격하게 증가하면서 의료기관 사이에 영상의 이동도 증가하고 있다. 이에 서로 다른 의료기관 간의 시스템 별 표준섭취계수 차이를 반영하기 위하여 1 Bed에서 표준섭취계수, 슬라이스 내의 표준섭취계수 변화율과 측정시간에 따른 표준섭취계수를 정량적으로 비교할 수 있는 팬텀을 이용한 비교측정이 필요하다. 본 연구에서는 임상에서 사용하는 다양한 PET/CT 시스템의 표준섭취계수 차이에 대한 연구를 통하여, PET/CT 영상의 표준화섭취계수의 신뢰성을 확보하고자 하였다. 대한민국 전국에 분포되어 의료기관에 설치된 PET/CT 장비 10대를 대상으로 하였으므로, 정확한 방사능 산출을 위하여, 한국표준과학원의 검출기로 검증을 통하여 실험하였다. NEMA PET $Phantom^{TM}$의 내부구조물을 제거하고 $^{18}F$-FDG 1 mCi를 6,000 mL 증류수에 균일하고 분포하도록 마그네틱 스터러와 마그네틱 바의 회전력으로 희석하여, 팬텀에 주입하였다. 주입 후 60분, 70분, 80분, 90분, 100분, 110분, 120분에 3분간 영상을 획득하고, 관심영역 $200\;cm^2$에 대하여 분석하였으며, 유용성 확인을 위하여 임상환자를 대상으로 교정표를 산출하였다. 1 Bed에서 표준섭취계수, 슬라이스 내의 표준섭취계수 변화율, 측정시간에 따른 표준 섭취계수 변화율과 함께 표준섭취계수의 변이계수가 -11.0~9.90%로 국제적으로 통용되는 기준인 ${\pm}10%$를 1개의 장비를 제외하고 모두 만족하였다. 또한, 시스템 별 평균 표준섭쉬계수 차이를 이용하여 0.803~1.246으로 이루어진 교정표를 도출하였고, 정상인을 통한 임상 적용에서 선형회귀분석을 통하여 유의함을 확인하였다. 본 연구를 통하여 PET/CT 장비간의 표준섭취계수 차이를 교정표를 이용하여 정량적으로 비교할 있는 근거를 제시한다면 정확한 진단에 도움이 되며, 아울러 이에 대한 세계적 기준이 명확하지 않기에 유사 연구에 도움이 되리라 사료된다.
Purpose: As the number of domestic medical institutions installing PET/CT is increasing rapidly, the transfer of PET/CT images among medical institutions is also increasing. Thus, it is necessary to collect the comparative SUV data from several medical institutions' PET/CT systems through a phantom ...
Purpose: As the number of domestic medical institutions installing PET/CT is increasing rapidly, the transfer of PET/CT images among medical institutions is also increasing. Thus, it is necessary to collect the comparative SUV data from several medical institutions' PET/CT systems through a phantom study which semi-quantitatively compares the SUV on one bed, the change scale of the SUV on the slices, and the time of measuring. The phantom study to find differences among the SUVs from various PET/CT offers the opportunity to obtain the reliability of the SUV in PET/CT images. Materials and Methods: Ten PET/CT systems from medical institutions in Korea were used. To obtain the accurate data, the study has been using the radiation detector of Korea Research Institute of Standards and Science to verify. The internal structures of NEMA $phantom^{TM}$ were removed and Six thousand milliliters of distilled water which has 1mCi of $^{18}F$-FDG put into the phantom. The water was properly integrated with $^{18}F$-FDG using magnetic stirrer. The images were acquired at 60, 70, 80, 90, 100, 110 and 120-minutes for 3 minute each. Two hundred square centimeters of region of interests were placed and analyzed. To confirm the usefulness, the correction-table came out from patients' data. Results: The coefficient of variability of the SUV from -11.0 to 9.90 % fell into the range of international standards(${\pm}10%$) along with the SUV on a bed, the change scale of the SUV on the slices, and the time of measuring, except one PET/CT system. Using the data of the differences among the SUVs, we came to withdraw the correction-table ranging from 0.803 to 1.246. The correction-table was confirmed its usefulness through Linear Regression Analysis which was applied to normal cases. Conclusions: Although studies have been made on the variation of the SUV, there is little attention on the standardization of the SUV. Based on this study of the quantitatively comparable data about the SUV accommodating the correction-table, it would help to have more corrective diagnosis.
Purpose: As the number of domestic medical institutions installing PET/CT is increasing rapidly, the transfer of PET/CT images among medical institutions is also increasing. Thus, it is necessary to collect the comparative SUV data from several medical institutions' PET/CT systems through a phantom study which semi-quantitatively compares the SUV on one bed, the change scale of the SUV on the slices, and the time of measuring. The phantom study to find differences among the SUVs from various PET/CT offers the opportunity to obtain the reliability of the SUV in PET/CT images. Materials and Methods: Ten PET/CT systems from medical institutions in Korea were used. To obtain the accurate data, the study has been using the radiation detector of Korea Research Institute of Standards and Science to verify. The internal structures of NEMA $phantom^{TM}$ were removed and Six thousand milliliters of distilled water which has 1mCi of $^{18}F$-FDG put into the phantom. The water was properly integrated with $^{18}F$-FDG using magnetic stirrer. The images were acquired at 60, 70, 80, 90, 100, 110 and 120-minutes for 3 minute each. Two hundred square centimeters of region of interests were placed and analyzed. To confirm the usefulness, the correction-table came out from patients' data. Results: The coefficient of variability of the SUV from -11.0 to 9.90 % fell into the range of international standards(${\pm}10%$) along with the SUV on a bed, the change scale of the SUV on the slices, and the time of measuring, except one PET/CT system. Using the data of the differences among the SUVs, we came to withdraw the correction-table ranging from 0.803 to 1.246. The correction-table was confirmed its usefulness through Linear Regression Analysis which was applied to normal cases. Conclusions: Although studies have been made on the variation of the SUV, there is little attention on the standardization of the SUV. Based on this study of the quantitatively comparable data about the SUV accommodating the correction-table, it would help to have more corrective diagnosis.
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제안 방법
For an accurate calculation from the radiation of 18F-FDG which goes into Phantom, we compared the Dose Calibrators normally used for PET/CT systems were compared by measuring the accuracy and precision, and corrected the radiation. 18F-FDG was produced from the Cyclotron HM-18 (Sumitomo Heavy industries, Ltd.
The accuracy and precision of Dose Calibrators were obtained and corrected to have quantitative analysis and to calculate the accurate level of radiation. The usefulness was confirmed as the correction-table about the differences of SUV of PET/CT systems applied for clinical data.
The images were acquired at 60, 70, 80, 90, 100, 110 and 120-minutes from the beginning of the injection.
3. To check the repeatability, the images were acquired at 60, 70, 80, 90, 100, 110 and 120-minutes. SUV were measured.
대상 데이터
NEMA PET PhantomTM(NU2-1994) was used (Table 1).
Positron emission tomography (PET) is a nuclear medicine imaging technique which produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays which has 511 KeV as the energy emitted indirectly on the 180 degrees by a positron-emitting radionuclide.PET scans are increasingly read alongside CT scan, the combination could give both anatomic and metabolic information.
데이터처리
The usefulness was confirmed as comparing between the correction-table of SUV differences and the correction-table of phantom SUV drawing in both lung and 3 areas of the liver. In terms of having the statistical confidence level of usefulness, a coefficient of correlation was taken through a linear regression analysis (Fig. 4).
Precision was calculated from RMSE (Root Mean Square Error).
성능/효과
In 60 minutes delayed images, The averages and standard deviations of G1, G2, G3, S1, S2, and S3 about SUVmean of ROI in one slice of the image and SUVmean of the valid area in one bed image are 0.934±0.072, 1.045±0.091, 1.065±0.185, 0.951±0.046, 1.098±0.079, and 0.884±0.059, respectively (Fig. 6).
In 60 minutes delayed images, the averages and standard deviations of G1, G2, G3, S1, S2, and S3 about SUVmax of ROI in one slice of the image and SUVmax of the valid area in one bed image are 1.210±0.048, 1.409±0.064, 1.780±0.099, 1.115±0.020, 1.372±0.049, and 1.098±0.02, respectively (Fig. 7).
In the results of the measurement of 9 Dose calibrators, 6 were less than 2% and 3 were more than 5%. The largest fluctuation of the numerical value was 9% (-5% and +4.
On the Region of Interest of images acquired at 60, 70, 80, 90, 100, 110 and 120-minutes from the beginning of the injection, Coefficient of Variability of Repeatability of SUV max for G1, G2, G3, S1, S2, and S3 are 0.19%, 0.18%, 0.24%, 0.30%, 0.16%, and 0.27%, respectively (Table 4.).
On the Region of Interest of images acquired at 60, 70, 80, 90, 100, 110 and 120-minutes from the beginning of the injection, Coefficient of Variability of Repeatability of SUV mean for G1, G2, G3, S1, S2, and S3 are 0.19%, 0.18%, 0.24%, 0.30%, 0.16%, and 0.27%, respectively (Table 3.).
The SUV Coefficient of Variability(%) which shows the proportions of SUVmean and standard deviations of G1, G2, G3, S1, S2, and S3 are 8.078%, 9.092%, 18.121%, 5.124%, 7.4787%, and 6.904%, respectively (Fig. 8).
The correlation coefficient from the linear regression analysis which was compared the correction-table of the difference of SUVtotal-max from PET/CT systems in the region of both lung and liver with the correction-table of SUVmax of the phantom were 0.93458 (p<0.0001), 0.98488 (p<0.0001), 0.79443 (p=0.00202), 0.89832 (p<0.0001), respectively (Fig. 13).
The correlation coefficient from the linear regression analysis which was compared the correction-table of the difference of SUVtotal-mean from PET/CT systems in the region of both lung and liver with the correction-table of SUVmean of the phantom were 0.97184 (p<0.0001), 0.87981 (p=1.60898E-4), 0.85245 (p=4.27671E-4), 0.88938 (p<0.0001), respectively (Fig. 12).
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