Voxel-Based Dosimetry of Iron Oxide Nanoparticle-Conjugated ¹⁷⁷Lu-Labeled Folic Acid Using SPECT/CT Imaging of Mice

Gupta, Arun,Shin, Jae H.,Lee, Min S.,Park, Ji Y.,Kim, Kyuwan,Kim, Joong H.,Suh, Minseok,Park, Cho R.,Kim, Young J.,Song, Myung G.,Jeong, Jae M.,Lee, Dong S.,Lee, Yun-Sang,Lee, Jae S. American Chemical Society 2019 Molecular pharmaceutics Vol.16 No.4

<P>Several radiolabeled folic acid conjugates have been developed for targeted imaging and therapy. However, the therapeutic concept with radiolabeled folate conjugates has not yet been applied to clinical applications owing to the high renal absorbed dose. The effectiveness of targeted radionuclide therapy (TRT) depends primarily on the absorbed dose rate and on the total absorbed dose delivered to the tumor and to normal tissue. Owing to various limitations associated with organ level dosimetry, voxel-based dosimetry has become essential for the assessment of a more accurate absorbed dose during TRT. In this study, we synthesized iron oxide nanoparticle (IONP)-conjugated radiolabeled folate (<SUP>177</SUP>Lu-IONP-Folate) and performed voxel-based dosimetry using SPECT/CT images of normal mice through direct Geant4 application for emission tomography (GATE) Monte Carlo (MC) simulation. We also prepared <SUP>177</SUP>Lu-Folate and <SUP>177</SUP>Lu-IONPs for the comparison of absorbed doses with that of <SUP>177</SUP>Lu-IONP-Folate. In addition, we calculated the mean absorbed dose at the organ-level using the medical internal radiation dose (MIRD) schema. The radioactivities of all three radiotracers were mainly accumulated in the liver and kidneys immediately after injection. For the kidneys, the voxel-based absorbed doses obtained with <SUP>177</SUP>Lu-IONP-Folate, <SUP>177</SUP>Lu-Folate, and <SUP>177</SUP>Lu-IONPs were 1.01 ± 0.17, 2.46 ± 0.50, and 0.52 ± 0.08 Gy/MBq, respectively. The renal absorbed dose decreased significantly (∼half) when <SUP>177</SUP>Lu-IONP-Folate was used compared with when the <SUP>177</SUP>Lu-Folate only was used. The mean absorbed dose values obtained at organ-level using the MIRD schema were comparable to voxel-based absorbed doses estimated with GATE MC. The voxel-based absorbed dose values obtained in this study of individualized activity show that the renal absorbed dose could be reduced to almost half with <SUP>177</SUP>Lu-IONP-Folate. Therefore, <SUP>177</SUP>Lu-IONP-Folate could be clinically applicable in the TRT of folate receptor-positive cancers in a personalized manner when using the voxel-based dosimetry method.</P> [FIG OMISSION]</BR>

CT검사 시 방사선 흡수선량에 따른 혈액학적 변화 관찰

최연상(Yeon Sang Choi),박환상(Hwan Sang Park),정창기(Chang Gi Jeong),이종호(Jong Ho Lee),최남길(Nam Gil Choi) 대한CT영상기술학회 2012 대한CT영상기술학회지 Vol.14 No.1

목적 환자의 CT검사 시 흡수선량에 따른 혈액수치를 검사 전과 검사 후로 나누어 흡수선량범위에 따른 급성장애에 관한 혈액학적 변화 관계를 알아보고자 한다. 대상과 방법 2011년 5월부터 7월까지 CT검사를 시행한 병동환자(남: 74명, 여: 53명-평균연령 60.9세)를 중심으로 검사 전 혈액검사 검사 후 1~2일 후 혈액검사결과를 수집하여 흡수선량 범위(500mGy 이하, 500~1000mGy, 1000 mGy 이상)를 구분, 환자의 급성장애에 관한 혈액수치를 비교 분석하였다. *사용장비: GE Light VCT (Dose Report: DLP <mGy-cm>) 결과 1. CT 검사 전과 검사 후(혈액검사 1~2일 후 이내) 혈액수치결과. 127명(남: 74명, 여: 53명) 평균나이: 60.9세 평균Dose: 846mGy-cm WBC(5.6→4.9) 10³/mm³ 12,5% 감소, RBC(4.8→4.5) 106/mm³ 6,3% 감소, Platelet(l76.9→165.6) 10³/mm³ 6.4% 감소, Lymphocyte(20.7%→19.2%) 7.2% 감소. 1) 500mGy-cm 이하:(남: 23명, 여: 13명) 평균나이: 60.2세, 평균Dose DLP 452 mGy-cm WBC(5.4→5.1) 10³/mm³ 5.6% 감소, RBC(5.1→4.9) 10⁶/mm³ 3.9% 감소 Platelet(185.1→178.3) 10³/mm3 3.7% 감소, Lymphocyte(18.2%→17.8%) 2.2% 감소. 2) 500mGy~1000mGy-cm: (남: 27명, 여: 15명) 평균나이: 60.5세 평균 DLP Dose: 867mGy-cm WBC(5.8→5.2) 10³/mm3 10.3% 감소, RBC(4.5→4.2) 10⁶/mm³ 6.7% 감소 Platelet(191.4→183.2) 10³/mm3 4.3% 감소, Lymphocyte(20.9%→19.4%) 7.2% 감소. 3) 1000mGy-cm 이상 -(남: 30명, 여: 19명) 평균나이: 61.2세 평균 DLP Dose: 1356 mGy-cm WBC(5.7→4.6)10³/mm³ 19.3% 감소, RBC(4.7→4.3) 10⁶/mm³ 8.5% 감소, Platelet(154.2→135.4) 10³/mm³ 12.2% 감소, Lymphocyte(23.1%→20.3%) 12.1% 감소. 결론 CT검사 전과 검사 후 흡수선량의 범위에 따른 혈액수치를 비교해 본 결과 검사 전에 비해 WBC, RBC, Platelet Count, Lymphocyte 수치 모두 검사 후에 혈액수치가 감소하였으며 흡수선량이 높은 구간에서 혈액수치의 감소폭이 비교적 높게 나타나는 걸 확인할 수 있었다. I. Purpose Absorbed dose during CT examinations of patients according to blood tests before and after the test is divided into levels. According to the absorbed dose range for acute disorders To evaluate the relationship between changes in hematology. II. MATERIALS and METHODS May to July 2011 who underwent CT scans ward patients (M: 94, F: 63 people - average age 60.9 years) before checking into the center of one to two days after a blood test after the test results of blood tests were collected. Absorbed dose range(less than 500mGy, 500~1000mGy, more than 1000mGy) separate the patients with acute disorders of On the blood levels were compared. *Equipment used: GE Light speed VCT (Dose Report: DLP <mGy-cm>) III. Result 1. CT scans before and after the test (blood test within 1-2 days)127 People (M: 74, F: 53), Average age: 60.9, Average DLP Dose: 846 mGy-cm WBC(5.6→4.9) 10³/mm³: 12.5% reduction, RBC(4.8→4.5) 106/mm³: : 6.3% reduction, Platelet(176.9→165.6) 10³/mm³: 6.4% reduction, Lymphocyte(20.7%→19.2%): 7.2% reduction. 1) Less than 500 mGy-cm People(M:23, F:13) Average age: 60.2, Average DLP Dose: 452 mGy-cm WBC (5.4→5.1) 10³/mm³: 5.6% reduction, RBC(5.1→4.9) 106/mm³: 3.% reduction Platelet(185.1→178.3) 10³/mm³: 3.7% reduction, Lymphocyte (18.2%→17.8%): 2.2% reduction 2) 500 mGy~1000 mGy-cm People(M:27, F:15), Average age:60.5, Average DLP Dose: 867 mGy-cm WBC(5.8→5.2) 10³/mm³: 10.3% reduction, RBC(4.5→4.2)106/mm³: 6.7% reduction Platelet(191.4→183.2) 10³/mm³: 4.3% reduction, Lymphocyte(20.9%→19.4%): 7.2% reduction 3) More than 1000mGy-cm People(M:30,F:19) Average age: 61.2, Average DLP Dose: 1356 mGy-cm WBC(5.7→4.6) 10³/mm³: 19.3% reduction, RBC(4.7→4.3) 106/mm³: 8.5% reduction, Platelet(154.2→135.4) 10³/mm³: 12.2% reduction, Lymphocyte (23.1%→20.3%): 12.1% reduction. IV. Conclusion CT scans before and after the test to the range of absorbed dose results in blood levels were compared. Before the test, compared to the WBC, RBC, Platelet Count, Lymphocyte numbers in blood levels after checking all the Decreased. In particular, the higher the absorbed dose to blood levels were more significantly reduced actin know.

Estimating the Absorbed Dose to Critical Organs During Dual X-ray Absorptiometry

M Mokhtari-Dizaji,A A Sharafi,B Larijani,N Mokhlesian,H Hasanzadeh 대한영상의학회 2008 Korean Journal of Radiology Vol.9 No.2

Objective: The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom. Materials and Methods: An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus. Results: There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 Gy and 1.81 Gy, respectively. Also, the scan center dose in the women was 5.70 Gy. There was correlation between the thyroid and uterus surface doses, and the scan center dose. Conclusion: We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry. Objective: The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom. Materials and Methods: An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus. Results: There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 Gy and 1.81 Gy, respectively. Also, the scan center dose in the women was 5.70 Gy. There was correlation between the thyroid and uterus surface doses, and the scan center dose. Conclusion: We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry.

Urography CT에서 Low dose protocol 사용시 선량 감소 효과에 관한 연구

김기범(Ki Bum Kim),이상우(Sang woo Lee) 대한CT영상기술학회 2013 대한CT영상기술학회지 Vol.15 No.1

목적 : CT 검사 중 다소 긴 시간과, 여러 phase를 가진 Urography CT 검사에서의 과거 조건과, low dose를 사용한 현재의 조건에서의 환자의 주요장기의 직접적인 선량을 비교하고, 이에 따른 noise를 측정, 임상의 유용성을 평가해보고자 한다. 대상 및 방법 : 본원에서 Urography CT검사로 follow-up 시행하는 총 20명의 환자를 대상으로 진행하였고, 사용된 장비는 64-MDCT Light Speed VCT Xte(USA), Rando phantom(Model ART-200-5 Fluke Biomedical) 그리고 Glass Dosimetry System(Dose Ace FGD-1000, GD-352M, Asahi Techno Glass Corporation Shizuoka, Japan)을 사용하여 실험하였다. Noise 분석은Image J- software(version 1.46r, National Institutes of Health, USA)를 통하여 SD값을 도출하였다. 이전의 기존 protocol과 low dose 조건을 사용한 현재의 protocol 로 각각 CTDIvol, DLP값을 비교 및 통계분석하고, 유리선량계를 Rando phantom의 비뇨기계 중요장기 부위에 직접 삽입하여 선량을 산출하였다. 결과 : 본 연구에서의 방사선 피폭선량에 대한 비교는 환자를 대상으로 한 통계치에서 CTDIvol은 평균 41%, DLP값은 49% 감소하였고, phantom을 사용하여 시행한 실험에서는 CTDIvol은 12%, 그리고 DLP값은 24%의 감소를 확인할 수 있었다. 중요장기부위의 선량계를 직접 삽입하여 산출해낸 부분 흡수선량은 오른 신장은 41%, 왼 신장은 42% 크게 감소하였고, 요관과 방광에서는 각각 0.5%, 4%의 증가를 보였다. 다른 비교대상인 software를 이용한 noise 측정에서는unenhanced phase에서는 33%의 큰 증가를 보였지만, low dose를 적용한 enhanced abdomen pelvis와 excretory phase에서는 증가를 보였다. 결론 : 환자의 피폭선량에는 큰 변화를 주었지만, mAs 감소로 인한 noise가 증가하였다. 하지만 low-dose가 적용된 phase에서는 큰 차이가 없었고, standard algorithm, ASIR가 작용하여 영상의 질에는 크게 작용하지 않았다. 하지만 흡수선량 측정에 있어, 주요장기만을 측정하였기에, 전체 선량은 훨씬 초과 할 것이며, 이에 있어 다른 검사조건을 조절 및 적용하면 선량의 최적화 및 환자의 선량 감소에 더욱 유용할 수 있을 것으로 사료된다. Purpose : The Urography CT has multiphase and scan is long time than others. This former and current low dose adaptive protocol were compared with radiation dose of patient to sensitive organ and noise of image. And than, tried to evaluate the clinical usefulness. Materials and Methods : The Target is total 20 patients performed follow-up Urography CT scan, scanner was performed with a 64-slice MDCT VCT Light Speed Xte (GE Healthcare, USA), Rando phantom(Model ART-200-5 Fluke Biomedical) and Glass Dosimetry System (Dose Ace FGD-1000, GD-352M, Asahi Techno Glass Corporation Shizuoka, Japan). The noise was analyzed in SD by using image J software (version 1.46r, National Institutes of Health, USA). The former protocol and low dose pointed protocol, measured CTDIvol and DLP value. Also the glass dosimeter was inserted in phantom sensitive organ, exposure dose was calculated. Results : When patient statistics were Compared with the before-after study, radiation dose was reduced to average 41% in CTDIvol and 49% in DLP value. Using the phantom, radiation dose was reduced to average 12% in CTDIvol and 24% in DLP value. The absorbed dose of phantom sensitive organ was decreased to average 41% in RT(right kidney) and 42% in LT(left kidney). The ureter and bladder was a little increase to 0.5% and 4%, but there is not much difference. In other comparable noise value was great increase 33% in unenhanced phase, however applying the low dose the enhanced abdomen pelvis and excretory phase was not that different. Conclusion : The patient radiation dose was great variance. If the mAs decreased, noise increased. But it was not much slight contrast in the low dose phase adaptation, owing to standard algorithm, practiced ASIR. Then, direct absorbed dose measured only sensitive organ, all body absorbed dose was predicted to exceed data. Consequentially, If applied the other conditions, can provide reducing absorbed dose to patients and balance radiation dose.

Bias-corrected H_p(10)-to-Organ-Absorbed Dose Conversion Coefficients for the Epidemiological Study of Korean Radiation Workers

Jeong, Areum,Kwon, Tae-Eun,Lee, Wonho,Park, Sunhoo The Korean Association for Radiation Protection 2022 방사선방어학회지 Vol.47 No.3

Background: The effects of radiation on the health of radiation workers who are constantly susceptible to occupational exposure must be assessed based on an accurate and reliable reconstruction of organ-absorbed doses that can be calculated using personal dosimeter readings measured as H_p(10) and dose conversion coefficients. However, the data used in the dose reconstruction contain significant biases arising from the lack of reality and could result in an inaccurate measure of organ-absorbed doses. Therefore, this study quantified the biases involved in organ dose reconstruction and calculated the bias-corrected H_p(10)-to-organ-absorbed dose coefficients for the use in epidemiological studies of Korean radiation workers. Materials and Methods: Two major biases were considered: (a) the bias in H_p(10) arising from the difference between the dosimeter calibration geometry and the actual exposure geometry, and (b) the bias in air kerma-to-H_p(10) conversion coefficients resulting from geometric differences between the human body and slab phantom. The biases were quantified by implementing personal dosimeters on the slab and human phantoms coupled with a Monte Carlo method and considered to calculate the bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients. Results and Discussion: The bias in H_p(10) was significant for large incident angles and low energies (e.g., 0.32 for right lateral at 218 keV), whereas the bias in dose coefficients was significant for the posteroanterior (PA) geometry only (e.g., 0.79 at 218 keV). The bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients derived in this study were up to 3.09- fold greater than those from the International Commission on Radiological Protection publications without considering the biases. Conclusion: The obtained results will aid future studies in assessing the health effects of occupational exposure of Korean radiation workers. The bias-corrected dose coefficients of this study can be used to calculate organ doses for Korean radiation workers based on personal dose records.

Comparative Study of the Effective Dose from Panoramic Radiography in Dentistry Measured Using a Radiophotoluminescent Glass Dosimeter and an Optically Stimulated Luminescence Detector

Kyeong Hee Lee,Myeong Seong Kim,Dae Cheol Kweon,Jiwon Choi 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.9

Accurate measurement of the absorbed dose and the effective dose is required in dental panoramic radiography involving relatively low energy with a rotational X-ray tube system using long expo- sures. To determine the effectiveness of measuring the irradiation by using passive dosimetry, we compared the entrance skin doses by using a radiophotoluminescent glass dosimeter (RPL) and an optically stimulated luminescence detector (OSL) in a phantom model consisting of nine and 31 transverse sections. The parameters of the panoramic device were set to 80 kV, 4 mA, and 12 s in the standard program mode. The X-ray spectrum was applied in the same manner as the panoramic dose by using the SpekCalc Software. The results indicated a mass attenuation coe- cient of 0.008226 cm2/g, and an effective energy of 34 keV. The equivalent dose between the RPL and the OSL was calculated based on a product of the absorbed doses. The density of the alu- minum attenuators was 2.699 g/cm3. During the panoramic examination, tissue absorption doses with regard to the RPL were a surface dose of 75.33 Gy and a depth dose of 71.77 Gy, those with regard to the OSL were surface dose of 9.2 Gy a depth dose of 70.39 Gy and a mean dose of 74.79 Gy. The effective dose based on the International Commission on Radiological Protection Publication 103 tissue weighting factor for the RPL were 0.742 Sv, 8.9 Sv, 2.96 Sv and those for the OSL were 0.754 Sv, 9.05 Sv, and 3.018 Sv in the parotid and sublingual glands, orbit, and thyroid gland, respectively. The RPL was more effective than the OSL for measuring the absorbed radiation dose in low-energy systems with a rotational X-ray tube.

Evaluated Absorbed Dose According to Prescribed Dose and Therapeutic Technique in Radiation Therapy

Deuk-hee Lee(이득희),Eun-tae Park(박은태),Jung-hoon Kim(김정훈),In-chul Im(임인철) 한국방사선학회 2016 한국방사선학회 논문지 Vol.10 No.6

본 논문에서는 움직이는 타깃을 대상으로 처방선량과 치료기법에 따른 흡수선량을 유리선량계를 이용하여 평가하였다. 타깃의 움직임에 따라 조사야에서 벗어나는 정도에 따른 선량을 MCNPX를 이용하여 모의 모사하였으며 그 결과 조사야에서 이격하는 거리에 비례하여 감소하는 것으로 나타났다. 처방선량에 따른 흡수선량의 결과는 3D CRT의 경우 저선량에서 IMRT보다 흡수선량이 높은 것으로 나타났으며, 대선량에서는 IMRT가 더 높은 비율을 보였다. 치료기법에 따른 결과는 3D CRT가 가장 우수한 것으로 나타났으며, IMRT의 sliding window방식이 가장 낮은 것으로 나타났다. 본 연구를 통하여 3D CRT가 움직이는 타깃에 가장 높은 선량을 조사할 수 있는 기법으로 평가되었다. 하지만 정상조직의 보호효과와 환자의 상태 등을 고려한 적절한 치료기법의 선택으로 치료효과를 높일 수 있는 노력이 필요할 것이다. In this study, evaluated absorbed dose of moving target using PLD according to prescribed dose and therapeutic technique. First, result of MCNPX when target was deviated from exposure field was reduced dose in proportion to distance. According to prescribed dose, absorbed dose of 3D CRT was better than IMRT in low dose and IMRT was more better in high dose. Absorbed dose of 3D CRT was highest according to therapeutic technique. Therefore, 3D CRT was technique of irradiated highest dose to moving target. But, considered protective effect of normal tissue and patient condition that therapeutic technique was selected to maximized treatment efficiency.

소아 5세 표준촬영 가이드라인과 임상 촬영조건의 입사표면선량과 주요 장기흡수선량 비교

강아름(Kang, A-Rum),이인자(Lee, In-Ja),안성민(Ahn Sung-Min) 대한방사선과학회(구 대한방사선기술학회) 2017 방사선기술과학 Vol.40 No.3

소아는 성인보다 장기의 방사선에 대한 감수성이 크고 성장 중이기 때문에 더 민감하다. 피폭으로 인한 부작용을 겪는 기대수명이 길기 때문에 피폭선량의 관리가 어른의 경우보다 중요하게 다뤄진다. 본 연구는 10세 팬텀을 사용하여 현재 우리나라에 권고되어 있는 5세 소아의 촬영기준과 입사표면선량의 적합성을 확인하고 추가적으로 제시된 촬영기준으로 장기흡수선량을 측정해보았다. 임상에서 사용 중인 5세와 10세의 촬영조건과 장기흡수선량, 입사표면선량을 비교하였다. 임상 5세 촬영조건이 권고촬영조건보다 약간 높으며 임상 10세 촬영조건은 많이 높게 나타났다. 또한 권고 촬영조건으로 ESD를 측정한 결과 임상 촬영조건의 ESD가 43% 높게 나타났으며 10세의 ESD 는 5세의 권고 촬영조건의 ESD 보다 126% 증가를 나타냈다. 5세의 권고된 ESD와 임상 촬영조건에 의한 ESD를 비교한 결과 31.6%의 차이를 나타냈다. 5세의 권고 촬영조건과 임상 촬영조건에 의한 장기흡수선량은 큰 차이는 없으나 흉부와 골반검사에서는 차이가 컸다. 그러나 10세의 임상 촬영조건에 의한 장기흡수선량을 비교하면 월등한 차이가 있었음을 알 수 있었다. 따라서 소아의 권고 선량에 대한 더욱 세분화된 기준안이 연구되어야 할 것으로 사료된다. Pediatrics are more sensibility to radiation than adults and because they are organs that are not com-pletely grown, they have a life expectancy that can be adversely affected by exposure. Therefore, the management of exposure dose is more important than the case of adult. The purpose of this study was to determine the suitability of the 10 year old phantom for the 5 year old pediatric s recommendation and the incident surface dose, and to measure the organ absorbed dose. This study is compared the organ absorbed dose and the entrance surface dose in the clinical conditions at 5 and 10 years old pediatric. Clinical 5 year old condition was slightly higher than recommendation condition and 10 year old condition was very high. In addition, recommendation condition ESD was found to be 43% higher than the ESD of the 5 year old group and the ESD of the 10 year old group was 126% higher than that of the 5 year old group. The recommended ESD at 5 years old and the ESD according to clinical imaging conditions were 31.6%. There was no significant difference between the 5 year old recommended exposure con-ditions and the organ absorbed dose due to clinical exposure conditions, but there was a large difference between the Chest and Pelvic. However, it was found that there was a remarkable difference when com-paring the organ absorbed dose by 10 year clinical exposure conditions. Therefore, more detailed standard exposure dose for the recommended dose of pediatric should be studied.

소아 Brain, Chest CT검사 시 차폐정도에 따른 유효선량 감소 효과에 관한 연구

김은경(Eun Kyeong Kim),이성주(Seong Joo Lee),유상재(Sang Jae Yu),김동성(Dong Seong Kim) 대한전산화단층기술학회 2014 대한CT영상기술학회지 Vol.16 No.2

목적 : 소아 brain, chest CT 검사 시 검사부위를 제외한 장기가 받는 흡수선량을 측정하고 이를 유효선량을 계산하여 차폐 정도에 따른 유효선량 감소 효과에 대하여 알아보고자 하였다. 대상 및 방법 : brⅢiance TM CT(WCT-500-140, Philips, Netherlands)장비로 5세 소아 phantom을 사용하여 phantom내 갑상선, 부신, 생식선 위치에 해당하는 organ hole에 광자극 발광 선량계를 각각 좌 우 두 개씩 삽입하고 검사부위를 제외한 부분을 전혀 차폐하지 않은 경우, 전면부만 덮어서 차폐한 경우, 전 후면을 둘러싸서 차폐한 경우로 구분하여 brain과 chest CT scan하여 흡수선량을 측정하였고 이를 유효선량으로 변환하였다. 선량 판독은 InLight microStar Reader기(LANDAUER, INC)를 사용하였다. 결과 : brain CT 검사에서 차폐를 전혀 하지 않은 경우를 기준으로 하였을 때 전면부만 차폐한 경우는 갑상선 17.72%, 부신 37.5%, 생식선 66.67%의 유효선량 감소율을 보였고 전체를 차폐한 경우는 갑상선 31.04%, 부신 84.38%, 생식선 66.67%의 유효선량 감소율을 보였다. 전면부만 차폐한 경우를 기준으로 하였을 때 전 후면 모두 차폐한 경우 갑상선 16.19%, 부신 75%, 생식선 0%의 유효선량 감소율을 보였다. chest CT검사에서 차폐를 전혀 하지 않은 경우를 기준으로 하였을 때 전면부만 차폐한 경우는 갑상선 41.94%, 부신 24.53%의 유효선량 감소율을 보였고, 생식선 11.11%로 유효선량이 증가하였다. 전체를 차폐한 경우는 갑상선 88.56%, 부신 46.4%, 생식선은 11.11%의 유효선량 감소율을 보였다. 전면부만 차폐한 경우를 기준으로 하였을 때 전 후면 모두 차폐한 경우 갑상선 80.3%, 부신 28.98%, 생식선 10%의 유효선량 감소율이 나타났다. 결론 : 소아 brain, chest CT검사 시 전면부만 차폐한 경우에 비해 전 후면 모두 차폐한 방법이 평균 35.08%의 유효선량 감소효과가 나타났으며 전혀 차폐하지 않은 경우보다 최고 88.56%의 유효선량 감소율을 보였다. 그러므로 CT검사의 특성을 고려하여 검사부위를 제외한 장기의 전 후면을 모두 차폐하여 검사하는 것이 불필요한 선량을 감소시키는데 유용할 것으로 생각된다. Purpose : Measuring the absorbed dose organ in pediatric brain and chest CT, as calculated in effective dose, and are let investigated effective dose reduction effect according to the degree of the shield. Materials and methods : It was inserted by two left and right in thyroid, adrenal, gonadal optically stimulated luminescence dosimeter in organ hole to use the phantom. And It was measured by separating non shield, half shield, in all around shield and measured the absorbed dose, which was converted to effective dose it. Results : On brain CT, when it was based on a half shield, all around shield showed a reduction ratio of thyroid 16.19%, adrenal 75%, gonads 0% effective dose. And when it was based on a half shield, all around shield showed a reduction ratio of thyroid 80.3%, adrenal 28.98%, gonads 10% effective dose in chest CT. Conclusion : On brain and chest CT, dose reduction of 35.08% has become clear that all round shield from non shield. And it showed a decrease of dose rate of 88.56% from the best all round shield. Therefore, it is useful to use all around shield is to reduce the dose in pediatric brain and chest CT.

An innovative idea for developing a new gamma-ray dosimetry system based on optical colorimetry techniques

Mihail-Razvan Ioan 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.3

Obtaining knowledge of the absorbed dose up-taken by a certain material when it is exposed to a specificionizing radiation field is a very important task. Even though there are a plenitude of methods fordetermining the absorbed dose, each one has its own strong points and also drawbacks. In this article, aninnovative idea for the development of a new gamma-ray dosimetry system is proposed. The methoddescribed in this article is based on optical colorimetry techniques. A color standard is fixed to the back ofa BK-7 glass plate and then placed in a point in space where the absorbed dose needs to be determined. Gamma-rayeinduced defects (color centers) in the glass plate start occurring, leading to a degree ofsaturation of the standard color, which is proportional, on a certain interval, to the absorbed dose. Afterthe exposure, a high-quality digital image of the sample is taken, which is then processed (MATLAB), andits equivalent IRGB intensity value is determined. After a prior corroboration between various well-knownabsorbed dose values and their corresponding IRGB values, a calibration function is obtained. By using thiscalibration function, an "unknown" up-taken dose value can be determined