• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2516-2523
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• 2024

This study aims to validate the dosimetric characteristics of Low Dose Rate (LDR) I-125 source Geant4-based Monte Carlo code. According to the recommendation of the American Association of Physicists in Medicine (AAPM) task group report (TG-43), the dosimetric parameters of a new brachytherapy source should be verified either experimentally or theoretically before clinical procedures. The simulation studies are very important since this procedure delivers a high dose of radiation to the tumor with only a minimal dose affecting the surrounding tissues. GEANT4 Monte Carlo simulation toolkit associated brachytherapy example was modified, adapted and several updated techniques have been developed to facilitate and smooth radiotherapy techniques. The great concordance of the current study results with the consensus data and with the results of other MC based studies is promising. It implies that Geant4-based Monte Carlo simulation has the potential to be used as a reliable and standard simulation code in the field of brachytherapy for verification and treatment planning purposes.

• Radiation Oncology Journal
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• 제29권3호
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• pp.199-205
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• 2011

Purpose: The present study compared the difference between intraoperative transrectal ultrasound (iTRUS)-based prostate volume and preplan computed tomography (CT), preplan magnetic resonance imaging (MRI)-based prostate volume to estimate the number of seeds needed for appropriate dose coverage in permanent brachytherapy for prostate cancer. Materials and Methods: Between March 2007 and March 2011, among 112 patients who underwent permanent brachytherapy with $^{125}I$, 60 image scans of 56 patients who underwent preplan CT (pCT) or preplan MRI (pMRI) within 2 months before brachytherapy were retrospectively reviewed. Twenty-four cases among 30 cases with pCT and 26 cases among 30 cases with pMRI received neoadjuvant hormone therapy (NHT). In 34 cases, NHT started after acquisition of preplan image. The median duration of NHT after preplan image acquisition was 17 and 21 days for cases with pCT and pMRI, respectively. The prostate volume calculated by different modalities was compared. And retrospective planning with iTRUS image was performed to estimate the number of $^{125}I$ seed required to obtain recommended dose distribution according to prostate volume. Results: The mean difference in prostate volume was 9.05 mL between the pCT and iTRUS and 6.84 mL between the pMRI and iTRUS. The prostate volume was roughly overestimated by 1.36 times with pCT and by 1.33 times with pMRI. For 34 cases which received NHT after image acquisition, the prostate volume was roughly overestimated by 1.45 times with pCT and by 1.37 times with pMRI. A statistically significant difference was found between preplan image-based volume and iTRUS-based volume (p<0.001). The median number of wasted seeds is approximately 13, when the pCT or pMRI volume was accepted without modification to assess the required number of seeds for brachytherapy. Conclusion: pCT-based volume and pMRI-based volume tended to overestimate prostate volume in comparison to iTRUS-based volume. To reduce wasted seeds and cost of the brachytherapy, we should take the volume discrepancy into account when we estimate the number of $^{125}I$ seeds for permanent brachytherapy.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2172-2174
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• 2014

• 한국의학물리학회지:의학물리
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• 제19권3호
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• pp.172-177
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• 2008

정량적인 방사선치료 선량을 예측하기위한 일환으로 한국표준남성에 기초하여 수학적 모의피폭체를 제작하였다. 이후 전립선을 선원장기로 하여 전립선암 근접치료 시 발생할 것으로 예상되는 전립선 및 주변장기의 흡수선량을 산정하였다. 모의모사를 위하여 방사성핵종은 전립선 근접치료에 유용하게 사용되는 $^{25}I$ 및 $^{103}Pd$선정하였고, 초기 방사능을 1 Ci를 투여하는 것으로 가정하였다. 그 결과 선원장기인 전립선이 $^{125}I$ 및 $^{103}Pd$ 경우 각각 101 Gy/Ci와 7.24 Gy/Ci를 나타냈으며, 전립선을 제외하고 흡수선량이 높은 장기는 비교적 전립선과 인접되어 있는 장기 즉 음경과 음낭, S자결장, 정소, 방광순으로 나타났다.

• 한국방사선학회논문지
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• 제10권1호
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• pp.39-44
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• 2016

본 연구는 전립선암의 치료방법 중 근접치료 시 환자 주변의 공간에 대한 선량을 평가한 것으로 환자, 시술자 그리고 보호자에 대한 선량을 예측함으로서 피폭을 최소한으로 예방하고자 수행하였다. 실험방법은 몬테칼로법을 기반으로 한 MCNPX를 사용하여 가상의 공간에서 모의피폭체를 만들어 실험하였으며, 선원은 $^{192}Ir$, $^{125}I$, $^{103}Pd$를 seed 형태로 이식하였다. 환자를 중심으로 전방 30, 50, 100, 200 cm 거리에 관심영역을 설정하여 공간 선량을 평가하였다. 그 결과 거리에 관계없이 $^{192}Ir$에서 가장 높은 선량을 나타내었다.

• 대한방사선치료학회지
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• 제6권1호
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• pp.56-60
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• 1994

In the past, brachytherapy was carried out mostly with radium or radon sources. Currently. use of artificially produced radionuclially produced radionuclides such as $^{137}Cs,\;^{192}Ir,\;^{198}Au,\;and\;^{125}I$ is rapidly increasing. Although electrons are often used as an alternative to interstitial implants, brachytherapy continues to remain an important mode of therapy, either alone or combined with external beam. The National Council on Radiation Protection and Measurements(NCRP) recommends that the strength of any ${\gamma}$ emitter should be specified directly in terms of exposure rate in air at a specified distance such as 1m. The air kerma strength is defined as the product of air kerma rate in 'free space' and the square of the disrance of the calibration point from the source center along the perpendicular bisector, i. e., $S_k=K_L{\times}L^2$. Where $S_K$ is the the air kerma strength and K is the air kerma rate at a specified distance L. (usually 1m). Recommended units for all kerma strength are ${\mu}Gym^{2}h^{-1}$.

• Asian Pacific Journal of Cancer Prevention
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• 제15권18호
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• pp.7805-7809
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• 2014

Objective: To explore the clinical efficacy and prognostic factors of chemoreduction combined with topical treatment of advanced intraocular retinoblastoma (RB). Materials and Methods: A total of 22 eyes from 17 children with RB were selected for the study and treated with chemoreduction combined with topical cryotherapy, transpupillary thermotherapy (TTT) or episcleral plaque brachytherapy. Clinical and follow-up data were retrospectively analyzed. Results: All children received 2~6 courses of chemoreduction treatment, ($4.5{\pm}0.8$ courses on average); 17 eyes from 13 children were treated by chemoreduction combined with cryotherapy or TTT and 5 eyes from 4 children with chemoreduction combined with $^{125}I$ episcleral plaque brachytherapy. The eye retention rate was 81.8% (18/22), among which 38.9% (7/18) featured restored or maintained good vision. Postoperative follow-up period was 7 to 34 months, ($18.6{\pm}5.2$ months on average). The recurrence rate was 41.2% (7/17), among which 57.1% (4/7) were controlled by supplementing or appending cryotherapy or TTT treatment during the follow-up period. The tumor basal diameter and thickness were significantly reduced (P<0.05 or P<0.01) after treatment. All children demonstrated different degrees of hair loss, 70.6% (12/17) with different degrees of gastrointestinal reactions, 5.88% (1/17) with neutropenia and 11.8% (2/17) being seriously infected during the chemotherapeutic treatment. Univariate and logistic regression analysis showed that tumor basal diameter before treatment had a significant effect on the prognosis (P<0.01). Conclusions: Chemoreduction combined with topical therapy can effectively control RB in the short term, and tumor basal diameter before treatment is an independent risk factor for prognosis.

• Asian Pacific Journal of Cancer Prevention
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• 제15권20호
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• pp.9009-9013
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• 2014

Background: The aim of this study was to explore the efficacy and adverse reactions of CT-guided radioactive 125I-seed implantation treatment combined with chemotherapy for platinum-resistant recurrent ovarian carcinoma. Materials and Methods: From September 2010 to December 2012, 23 patients with platinum-resistant recurrent ovarian carcinoma were enrolled. All the patients refused, could not bear, or were not suitable for surgery. They all had no more than 3 lesions, which were detected and could also be measured by CT. All were clarified as single-lesion or multiple-lesion groups. A total of 41 lesions underwent implantation of from 8 to 106 125I seeds (median=43). Multi-plane implanting was adopted and 125I-seeds of (0.4-0.7)mCi were placed at intervals of (0.5-1.0) cm. After implantation treatment, all patients underwent 4 cycles of chemotherapy with gemcitabine $800mg/m^2$ (days 1, 8 and 15). Results: The outcome was evaluated with CT 3 weeks and every 3 months after implantation treatment. After 6 months, the volume of 32 out of 41 lesions (78.0%) was reduced at least 30%, within which 9 lesions completely disappeared(22.0%). Complete response was observed in 7 cases (30.4%), with a partial response in 4 cases (17.4%), 4 cases stable(17.4%)and 8 cases showing progression (34.8%). The total clinical remission rate was 47.8% (11/23). The clinical remission rate was 77.8% (7/9) in the single-lesion group and 28.6% (4/14) in the multiple-lesion group with a significant difference between the two(P=0.036). The common side effects observed were mild gastrointestinal reactions. Conclusions: 125I-seed implantation combined with chemotherapy applies an effective way in the treatment of platinum-resistant recurrent ovarian epithelial carcinoma with the advantages of high local control rates, good short-term effects, little trauma and less side effects.

• Radiation Oncology Journal
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• 제18권3호
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• pp.182-186
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• 2000

목적 : 수술을 시행하지 않은 식도암 환자에서 방사선치료 후 생존율 및 예후 인자를 파악하여 향후 치료 방침 결정에 도움이 되고자 한다. 대상 및 방법 : 1992년부터 1996년까지 원자력병원 방사선종양학과에서 근치적 또는 고식적 목적으로 치료를 받은 식도암 환자를 대상으로 하여 후향적 분석을 시행 하였다. 수술 또는 방사선치료 후 재발한 환자 및 방사선조사를 40 Gy 미만으로 받은 환자를 제외한 40명의 환자를 대상으로 하였다. 이 중 남자는 35명, 여자는 5명이었다. 2 명의 환자는 생검을 시행하지 않았고 그 외 환자는 모두 편평 상피암이었다. AJCC 1997 병기별 분포는 I 1명, IIA 6명, IIB 6명, III 10명, IVA 12명, IVB 4명 이고 병기를 알 수 혀는 경우가 1명이었다. 보조 항암화학요법을 시행한 환자는 모두 10명이었다. 조사선량의 범위는 $40\~60$ Gy이고 중앙선량은 59.4 Gy 였다. 결과 : 전체 환자의 중앙생존기간은 6.5개월이고 1년 생존율은 $28.3\%$이다. 연령 및 병변위치, 방사선량, 항암화학요법 추가에 관한 생존율의 차이는 관찰되지 않았다. 각각의 병기에 따라 생존율의 차이는 관찰되지 않아 임상병기는 예후에 큰 도움이 되지 않았다. 그러나 병기 III이내의 환자와 병기 tV이상의 환자 사이에는 통계학적으로 의미있지는 않았지만 중앙생존기간이 각각 7.6개월 및 6.2개월로 차이를 보였다. 결론 : 식도암의 생존율은 극히 불량하였다. 환자의 전신 상태 등을 고려하여 완치 및 고식적 목적을 구별하고 항암화학요법의 추가 및 스텐트(Stent), 또는 근접 조사치료를 추가 함으로 생존율의 증가 및 고식적 치료 목적을 달성하여야 할 것이다.본 연구에서는 근치적 수술 등 국소조절의 중요성이 강조되었다.모양이 불규칙한 병변에 대하여도 정위방사선치료를 확대 적용할 수 있겠다.m$1.35 mSv 였으며 법적 선량한도인 50mSv보다 훨씬 적은 량이지만 그 중 125명(36$\%$)은 방사선과 관련 없는 일반인의 방사선 피폭의 선량한도인 1년간 1 mSv 보다 많은 양의 피폭을 받고 있었다 연령에 따른 방사선 피폭은 30세이하에서 평균 1.87$\pm$1.01 mSV, 31세에서 40세 사이가 평균 1.22$\pm$0.69 mSV, 41세 이상에서 평균 0.97$\pm$0.43 mSV로 연령이 적을수록 많은 양의 피폭을 받고 있었다(p<0.01). 병원 내에서 방사선 피폭을 많이 받는 장소가 한정되어 있었다. 방사선을 취급하는 과별로 받는 년간 평균 피폭 선량은 진단방사선과 1.65$\pm$1.54mSv, 치료방사선과 1.17$\pm$0.82 mSv, 핵의학과 1.79$\pm$1.42 mSv, 기타 0.99$\pm$0.51 mSv였으며 상대적으로 저선량율 에너지를 사용하는 핵의학과에서 다른 과와 비교해서 방사선 피폭이 높게 나타났으며(p<0.05), 핵의학과 내에서는 특히 동위원소 조작실과 주입실의 년간 평균 피폭량이 3.69$\pm$1.81 mSv으로 많은 피폭을 받고 있었다(p<0.01). 진단방사선과 내에서는 대장 촬영실 근무자의 연평균 피폭량이 3.74$\pm$1.74 mSv로 가장 많이받고 있으며(p<0.01) 그외 투시진단법(Fluoroscopy) 등 직접 투시를 요하는 촬영실,