¹⁸F-FDOPA Brain PET/CT 검사의 영상 대조도 분석 및 섭취 시간에 따른 SUV변화 고찰

서강록,이정은,고현수,류재광,남기표,Seo, Kang rok,Lee, Jeong eun,Ko, Hyun soo,Ryu, Jae kwang,Nam, Ki pyo 대한핵의학기술학회 2019 핵의학 기술 Vol.23 No.1

$^{18}F$-FDOPA는 뇌 종양의 아미노산 대사를 추적하는 방사성 의약품이다. 본 연구의 목적은 뇌 종양의 아미노산 대사를 영상화 하여 악성 종양을 진단하는 $^{18}F$-FDOPA와 포도당 대사를 통한 $^{18}F$-FDG의 Brain PET/CT 검사 영상의 대조도 분석을 통해 병변의 검출 능력을 비교하고, $^{18}F$-FDOPA Brain PET/CT 검사에서 섭취 시간에 따른 SUV의 변화를 분석하여 최적의 영상 획득 시간을 알아보기 위함이다. $^{18}F$-FDOPA 와 $^{18}F$-FDG 두 영상에서 종양(Tumor)과 소뇌(Cerebellum)의 중심에 각각 약 $350mm^2$의 관심 영역을 설정하여 $SUV_{max}$를 측정하였고, 종양과 소뇌의 $SUV_{max}$ 비율(T/C ratio)을 산출하였고, $^{18}F$-FDOPA 투여 직후 30분 동안 획득한 리스트 수집 방식 데이터(List mode data)를 활용해 2분씩 15프레임으로 나눈 뒤 각 프레임 별로 종양과 소뇌 중심에 $SUV_{max}$를 측정하여 위와 동일한 방법으로 T/C ratio를 산출하여 분석하였다. 종양의 평균 $SUV_{max}$를 비교해 본 결과, $^{18}F$-FDOPA Brain PET/CT 검사에서 $4.2{\pm}0.8$, $^{18}F$-FDG Brain PET/CT 검사에서는 $5.6{\pm}0.7$ 이었다. 또한, T/C ratio는 $^{18}F$-FDOPA 검사에서 $2.1{\pm}0.7$, $^{18}F$-FDG 검사에서는 $1.1{\pm}0.4$ 이었으며, $^{18}F$-FDOPA의 $SUV_{max}$는 $^{18}F$-FDG보다 낮지만 T/C ratio는 높게 나타나 종양 구별 능력이 더욱 뛰어난 것을 알 수 있었다(t=-5.214, p=0.000). $^{18}F$-FDOPA의 섭취 시간에 따른 $SUV_{max}$와 T/C ratio를 분석한 결과, $SUV_{max}$와 T/C ratio의 Peak는 모두 6~8분에서 나타났다. 이를 토대로 본원에서 $^{18}F$-FDOPA Brain PET/CT 검사에서 활용하는 10~30분의 영상과 Peak가 나타나기 시작한 6~26분의 영상을 비교한 결과 SUV와 T/C ratio가 각각 0.2, 0.1 증가하였다. 추후 지속적인 연구를 통해 검사 소요시간의 단축 가능성과 추가적인 스캔 정보 활용을 통한 정확한 진단에도 도움이 될 것으로 사료된다. Purpose $^{18}F$-FDOPA using amino acid is particularly attractive for imaging of brain tumors because of the high uptake in tumor tissue and the low uptake in normal brain tissue. But, on the other hand, $^{18}F$-FDG is highly uptake in both tumor tissue and normal brain tissue. The purpose of study is to evaluate comparison of contrasts in $^{18}F$-FDOPA Brain PET/CT and $^{18}F$-FDG Brain PET/CT and to find out optimal scan time by analysis of variation in SUV with the passage of uptake time. Materials and Methods A region of interest of approximately $350mm^2$ at the center of the tumor and cerebellum in 12 patients ($51.4{\pm}12.8yrs$) who $^{18}F$-FDG Brain PET/CT and $^{18}F$-FDOPA Brain PET/CT were examined more than once each. The $SUV_{max}$ was measured, and the $SUV_{max}$ ratio (T/C ratio) of the tumor cerebellum was calculated. In the analysis of SUV, T/C ratio was calculated for each frame after dividing into 15 frames of 2 minutes each using List mode data in 25 patients ($49.{\pm}10.3yrs$). SPSS 21 was used to compare T/C ratio of $^{18}F$-FDOPA and T/C ratio of $^{18}F$-FDG. Results The T/C ratio of $^{18}F$-FDOPA Brain PET/CT was higher than the T/C ratio of $^{18}F$-FDG Brain, and show a significant difference according to a paired t-test(t=-5.214, p=0.000). As a result of analyzing changes in $SUV_{max}$ and T/C ratio, the peak point of $SUV_{max}$ was $5.6{\pm}2.9$ and appeared in the fourth frame (6 to 8 minutes), and the peak of T/C ratio also appeared in the fourth frame (6 to 8 minutes). Taking this into consideration and comparing the existing 10 to 30 minutes image and 6 to 26 minutes image, the $SUV_{max}$ and T/C ratio increased by 0.2 and 0.1 each, compared to the 10 to 30 minutes image for 6 to 26 minutes image. Conclusion From this study, $^{18}F$-FDOPA Brain PET/CT is effective when reading the image, because the T/C ratio of $^{18}F$-FDOPA Brain PET/CT was higher than T/C ratio of $^{18}F$-FDG Brain PET/CT. In addition, in the case of $^{18}F$-FDOPA Brain PET/CT, there was no difference between the existing 10 to 30 minutes image and 6 to 26 minutes image. Through continuous research, we can find possibility of shortening examination time in $^{18}F$-FDOPA Brain PET/CT. Also, we can help physician to accurate reading using additional scan data.

몬테카를로 전산해석을 이용한 6 MeV 전자가속기에서의 타겟과 필터의 두께에 따른 광자 스펙트럼에 대한 평가

서강록(Kang Rok Seo),김선아(Suna Kim),강보선(Bo Sun Kang) 한국방사선학회 2015 한국방사선학회 학술대회 논문집 Vol.2015 No.춘계

전자 선형가속기는 전자를 가속시켜 타겟에 충돌시킴으로서 전자의 운동에너지를 광자로 변환 시키는 장치로서 방사선 치료에 가장 일반적으로 사용되는 방사선치료기기이다. 가속된 전자가 타겟에 수직방향으로 충돌하면 제동복사가 일어나 연속 에너지스펙트럼을 가진 광자가 발생된다. 이 연속 스펙트럼은 타겟의 구성 물질과 두께가 변하면 크게 변한다. 본 연구에서는 몬테카를로 방사선 모의수송 코드인 MCNPX 2.7.0을 사용하여 6 MeV 가속전자가 텅스텐 타겟과 WHA(Tungsten Heavy alloy) 타겟에 입사할 때 각 각의 최대 광자방출 두께를 계산하였다. 타겟이 순수한 텅스텐일 때와 WHA일 때 광자 스펙트럼에는 유의한 차이가 관찰되지 않았으며, 최대 광자방출 두께는 두 경우 모두 대략 0.9 ∼ 1mm였다. 또한, 방사선 치료에 불필요한 저 에너지 광자를 효과적으로 감소시킬 수 있는 알루미늄의 두께에 따른 광자 에너지 스펙트럼을 계산하였고, K-특성엑스선의 강도를 1/10으로 감쇄시키는 알루미늄 여과판의 두께는 약 4 cm 정도임을 확인하였다. Electron Linear Accelerator is the most common equipment for radiation therapy which accelerates electrons and bombard them on to the target to convert the electron’s kinetic energy to photon. Bremsstrahlung occurs when the accelerated electrons bombard vertically to the target, and photons are generated in a continuous-energy spectrum. The energy spectrum of the photons is changed by the difference in the material and thickness of target. In this study, we calculated the thicknesses for the maximum photon emission when 6 MeV electron interact with tungsten target and WHA (Tungsten Heavy alloy) target using MCNPX 2.7.0 a Monte Carlo radiation simulated transport code. The significant difference in the photon spectrum between a pure tungsten and WHA was not observed, and the thickness for the maximum photon emission was approximately 0.9 ∼ 1 mm for both target materials. In addition, we calculated the energy spectrum of photons corresponding to the varying thickness of the aluminum filter that can effectively reduce the unwanted low-energy photons, and confirmed that the thickness of aluminium filter to attenuate the intensity of the K characteristic X-ray to 1/10 was 4 cm.

핵의학 투고 논문 분류 및 방향성 고찰

조호연,우영란,서강록,홍건철,Ho-Yeon, Cho,Yeong-Ran, Woo,Kang-Rok, Seo,Gun-Chul, Hong 대한핵의학기술학회 2022 핵의학 기술 Vol.26 No.2

Purpose Since 1985, the Korean society of nuclear medicine technology (KSNMT) has been engaged in academic activities related to nuclear medicine imaging. From 2017 to 2021, the papers published in the journal were classified by the specific fields to examine the trends in the research and the direction of nuclear medicine in comparison with the papers submitted to the Korean Society of Nuclear Medicine (KSNM) during the same period. Materials and Methods From 2017 to 2021, papers submitted to KSNMT and KSNM were classified and databaseization using the Excel program by submission type, examination equipment, and examination field. Through this data, the number of papers published in journals by year, the number of papers submitted by detailed fields, and key words by era were analyzed and compared. Results The papers included by journal was 57 KSNMT and 280 KSNM. The major large classification of equipment, PET, Planar and SPECT was 26.3%, 21.1%, 19.3% in the KSNMT, KSNM was 49.6%, 6.4%, and 9.3%, with 66.7% and 65.3%, respectively. the major medium classification of equipment, industrial safety, urogenital system, nervous system, and quality control accounted for 54.4% of the total papers of the total ratio in the KSNMT, while the medium classification of oncology, endocrine system, urogenital system, therapy, and nervous system accounted for 61.1% of KSNM. In the major small classification of image acquisition, improvement effect, and exposure management accounted for 70.2% in KSNMT, while the items of image acquisition, report, and improvement effect accounted for 60.7% in KSNM. The major keywords except for equipment-related keywords such as PET/CT, PET/MR, and SPECT were SUV, Planar Image, and Respiration Gating Method in KSNMT and Ga68, Thyroid, and Lymphoma in the KSNM. Conclusion When checking the last 5 years of submissions, we can see that KSNMT is mainly concerned with image acquisition using existing radiotracers, while KSNM has focused on new radiotracers such as ⁶⁸Ga, ¹⁷⁷Lu, etc., and new medical technologies of theranostic. It has been confirmed that more PET-related papers than other examination equipment will account for a greater number of papers, and it is believed that future submissions will also account for a higher proportion of PET-related papers than other equipment.