Assessment of Radiation Dose from Radioactive Wedge Filters during High-Energy X-Ray Therapy

Back, Geum-mun,Park, Sung Ho,Kim, Tae-Hyung Korean Society of Medical Physics 2017 의학물리 Vol.28 No.2

This paper evaluated the amount of radiation generated by wedge filters during radiation therapy using a high-energy linear accelerator, and the dose to the worker during wedge replacement. After 10-MV photon beam was irradiated with wedge filter, the wedge was removed from the linear accelerator, and the dose rate and energy spectrum were measured. The initial measurement was approximately 1 uSv/h, and the radiation level was reduced to 0.3 uSv/h after 6 min. The effective half-life derived from the dose rate measurement was approximately 3.5 min, and the influence of AI-28 was about 53%. From the energy spectrum measurements, a peak of 1,799 keV was measured for AI-28, while the peak for Co-58 was not measured in the control room. The peaks for Au-106 and Cd-105 were found only measurement was done without wedge removement from the linear accelerator. The additional doses received by the radiation worker during wedge replacement were estimated to be 0.08-0.4 mSv per year.

텅스텐 엣지 블록을 이용하여 Megavoltage (MV) 영상의 질 평가

민정환,손진현,김기원,이정우,손순룡,백금문,김정민,김연래,정재용,김상영,이도완,최보영,Min, Jung-Whan,Son, Jin-Hyun,Kim, Ki-Won,Lee, Jung-Woo,Son, Soon-Yong,Back, Geum-Mun,Kim, Jung-Min,Kim, Yeon-Rae,Jung, Jae-Yong,Kim, Sang-Young,Lee, Do- 한국의학물리학회 2012 의학물리 Vol.23 No.3

최근 백만 볼트 영상(megavoltage imaging, MVI)에서 급격히 발전해 온 디지털 방사선영상(digital radiography, DR)은 치료용 방사선영상 기술이 발전함에 따라 매우 정확하면서 간단하게 측정할 수 있는 일반적인 정도관리(quality assurance, QA) 방법을 요구하게 되었다. 본 연구의 목적은 일반적인 QA 방법과 computed radiography (CR) 장비를 사용하여 MVI의 변조전달함수(modulation transfer function, MTF), 잡음전력스펙트럼(noise power spectrum, NPS), 양자검출효율(detective quantum efficiency, DQE)를 평가하고자 하였다. 텅스텐으로 구성된 $19{\times}10{\times}1cm^3$ 두께의 엣지(edge) 블록을 사용하였으며, 6 MV energy를 사용하였다. 또한 검출기는 CR-IP (image plate), CR-IP-lead, the CR-IP-back (lanex TM fast back screen), CR-IP-front (lanex TM fast front screen)를 사용하였으며, pre-sampling MTF를 계산하였다. CR-IP의 MTF는 0.70 lp/mm를 나타내었고, CR-IP front의 MTF는 1.10 lp/mm로서 가장 높은 값의 고해상도 공간분해능을 보였다. 가장 우수한 검출기의 NPS는 CR-IP front screen에서 확인되었다. 공간주파수가 증가함에 따라 1.0 cycles/mm의 가까운 DQE를 획득하였다. 본 연구결과로서 자체 제작한 엣지 블록 방법은 MVI의 MTF, NPS, DQE를 평가하는 일반적인 QA 방법으로 사용될 수 있음을 확인하여 주었다. Digital Radiography (DR) has rapidly developed in megavoltage X-ray imaging (MVI). Thus, a very simple and general quality assurance (QA) method is required. The purpose of this study was to evaluate the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE) for MVI using general QA method and computed radiography (CR) device. We used tungsten edge block with $19{\times}10{\times}1cm^3$ thickness and 6MV energy. For detector, CR-IP (image plate), CR-IP-lead, the CR-IP-back (lanex TM fast back screen), CR-IP-front (lanex TM fast front screen) were used and pre-sampling MTF was calculated. The MTF of CR-IP-front showed the highest value with 1.10 lp/mm although the CR-IP showed the only 0.70 lp/mm. The best NPS was observed in CR-IP front screen. According to the increase in spatial frequency, our results showed that DQE was approximately 1.0 cycles/mm. The present study demonstrates that the QA method with our home-made edge block can be used to evaluate MTF, NPS and DQE for MVI.

비인강암의 세기조절방사선치료기술을 이용한 동시차등조사가속치료의 예비성적

이상욱(Sang wook Lee),백금문(Geum Mun Back),이병용(Byong Yong Yi),최은경(Eun Kyung Choi),김종훈(Jong Hoon Kim),안승도(Seung Do Ahn),신성수(Seong Soo Shin),김상윤(Sang Yoon Kim),남순열(Soon Yuhl Nam),최승호(Seung Ho Choi),김성배(Sung 대한두경부종양학회 2003 대한두경부 종양학회지 Vol.19 No.1

Purpose: To introduce our early experience with intensity-modulated radiotherapy (IMRT) in the treatment of nasopharyngeal carcinoma. Methods and Materials: Eight patients who underwent IMRT for no disseminated nasopharyngeal carcinoma at the Asan Medical Center between September 2001 and November 2002 were evaluate by prospective analysis. According to the 1997 American Joint Committee on Cancer staging classification, 5 had Stage III, and 3 had Stage IVB disease. The IMRT plans were designed to be delivered as a 'Simultaneous Modulated Accelerated Radiation Therapy' (SMART) using the 'step and shoot' technique with a MLC (multileaf collimator). Daily fractions of 2.2-2.5Gy and 1.9-2Gy were prescribed and delivered to the GTV and CTV and clinically negative neck node, respectively. The prescribed dose was 70A-79.0Gy to the gross tumor volume (GTV), 60Gy to the clinical target volume (CTV) and metastatic nodal station, and 46Gy to the clinically negative neck. All patients also received weekly cisplatin during radiotherapy. Acute and late normal tissue effects were graded according to the Radiation Therapy Oncology Group (RTOG) radiation morbidity scoring criteria. Results: Follow-up period was ranging from 5 to 18 months. All patients showed complete response and loco-regional control rate was 100% but one patient died of malnutrition due to treatment related toxicity. There were no Grade 3 or 4 xerostomia and all patients had experienced improvement of salivary gland function. Conclusion: 'Simultaneous Modulated Accelerated Radiation Therapy' (SMART) boost intensity-modulated radiotherapy technique allows parotid sparing as evidenced both clinically and by dosimetry. Initial tumor response and loco-regional control was promising. It is clinically feasible. A larger population of patients and a long-term follow-up are needed to evaluate ultimate tumor control and late toxicity.

전립선암 방사선치료 시 광자극발광선량계를 이용한 광중성자선량 평가

이주아(Joo Ah Lee),백금문(Geum Mun Back),김연수(Yeon Soo Kim),손순룡(Soon Yong Son),최관우(Kwan Woo Choi),유병규(Beong Gyu Yoo),정회원(Hoi Woun Jeong),정재홍(Jae Hong Jung),김기원(Ki Won Kim),민정환(Jung Whan Min) 대한방사선과학회(구 대한방사선기술학회) 2014 방사선기술과학 Vol.37 No.2

본 연구는 전립선암의 방사선치료에 적용되는 치료기법별 세기조절방사선치료의 적절한 조사문수의 선택 및 광중성자 피폭을 고려한 방사선 치료계획 수립을 위한 기초자료를 제공하고자 하였다. 연구대상은 2013년 9월부터 2014년 1월까지 5개월 동안 전립선암으로 방사선치료를 받은 환자 10명을 대상으로 하였다. 그리고 3-dimensional conformal radiotherapy (3D-CRT), volumetric-modulated arc radiotherapy (VMAT), intensity modulated radiation therapy (IMRT) 5, 7, 9 조사문으로 각각 치료계획을 수립하였다. 기술통계와 분산분석으로 광중성자선량의 평균적 차이를 비교하였으며, 상관관계분석과 회귀분석으로 상관성 및 영향을 분석하였다. 연구 결과, 치료기법별로는 3D-CRT가 가장 낮았다. 또한 IMRT가 가장 높게 측정되었으며, 통계적으로 매우 유의하였다 (p<.01). 세기조절방사선치료 조사문수별 광중성자선량은 평균 4.37 ± 1.08 mSv였으며, 조사문수 간에 통계적으로 매우 유의한 차이를 보였다(p<.01). 그리고 조사문수와 광중성자선량은 상관계수가 0.570으로 나타나 통계적으로 매우 유의한 양의 상관관계를 보였다 (p<.01). 조사문수와 광중성자 선량의 선형회귀분석 결과, 조사문수가 1단계 증가할 때마다 평균적으로 광중성자선량이 0.373배로 유의하게 증가하였다. 결론적으로 전립선암의 방사선치료에 빈번히 사용하고 있는 IMRT의 조사문수의 선택 및 광중성자 피폭선량 및 방사선 치료계획의 질적 수준 평가를 고려한 적절한 치료계획 선택에 있어 기초자료로 활용될 수 있으리라 기대된다. This study is to provide basic information regarding photoneutron doses in terms of radiation treatment techniques and the number of portals in intensity-modulated radiation therapy (IMRT) by measuring the photoneutron doses. Subjects of experiment were 10 patients who were diagnosedwithprostate cancer and have received radiation treatment for 5 months from September 2013 to January 2014 in the depart-ment of radiation oncology in S hospital located in Seoul. Thus, radiation treatment plans were created for 3-Dimensional Conformal Radiotherapy (3D-CRT), Volumetric-Modulated Arc Radiotherapy (VMAT), IMRT 5, 7, and 9 portals. The average difference of photoneutron dose was compared through descriptive statistics and variance analysis, and analyzed influence factors through correlation analysis and regression analysis. In summarized results, 3D-CRT showed the lowest average photoneutron dose, while IMRT caused the highest dose with statistically significance (p <.01). The photoneutron dose by number of portals of IMRT was 4.37 ± 1.08 mSv in average and statistically showed very significant difference among the number of portals (p <.01). Number of portals and photoneutron dose are shown that the correlation coefficient is 0.570, highly statistically significant positive correlation (p <.01). As a result of the linear regression analy-sis of number of portals and photoneutron dose, it showed that photoneutron dose significantly increased by 0.373 times in average as the number of portals increased by 1 stage. In conclusion, this study can be expected to be used as a quantitative basic data to select an appropriate IMRT plans regarding photo-neutron dose in radiation treatment for prostate cancer.

두경부 IMRT 및 VMAT 시 체적 감소가 전산화치료계획에 미치는 영향

엄기천(Ki-Cheon Um),김가중(Gha-Jung Kim),백금문(Geum-Mun Back) 대한방사선과학회(구 대한방사선기술학회) 2023 방사선기술과학 Vol.46 No.3

전산화단층모의치료기를 이용한 경기관지 근접치료환자의 치료계획에 관한 고찰

서동린,김대섭,백금문,Seo, Dong Rin,Kim, Dae Sup,Back, Geum Mun 대한방사선치료학회 2013 대한방사선치료학회지 Vol.25 No.1

목 적: 경기관지 근접치료에 이용되는 2차원 치료계획의 경우 환부를 확인하는 과정에서 종양의 위치 파악에 어려움이 있어 정확한 치료계획 분석이 어려울 수 있다. 이에 본 연구에서는 전산화단층모의치료기를 이용한 3차원 치료계획으로 환자의 치료계획을 비교 분석하고자 한다. 대상 및 방법: 2012년 6월 본원을 내원한 환자를 대상으로 전산화모의치료장비(Lightspeed RT, GE, USA)와 Oncentra Brachy planning system (Nucletron, Netherland)를 사용하여 3차원 치료계획을 시행하여 2차원 치료계획과 비교 분석하였다. 결 과: 분할 조사로 시행되는 경기관지 근접치료에서 매회 카테터의 위치 파악이 치료계획 상에서 확인 되었고, GTV 용적은 $3.5cm^3$, $3.3cm^3$로 확인 할 수 있었다. 또한 종양의 선량분포 파악이 용이하여 GTV에 대하여 첫 번째 치료 시 처방선량의 92%, 두 번째 치료 시 88%로 파악되어 선량전달 오차를 파악할 수 있었다. 결 론: 2차원 치료계획을 통한 근접치료의 문제점을 보완하기 위하여 치료용적과 선량분포의 정확한 파악과 분석이 가능한 3차원 치료계획으로 검증이 필요하고, 선량전달 오차를 정량적으로 파악하여 치료계획에 반영하는 과정이 필요하다고 생각된다. Purpose: Transbronchial brachytherapy used in the two-dimensional treatment planning difficult to identify the location of the tumor in the affected area to determine the process analysis. In this study, we have done a comparative analysis for the patient's treatment planning using a CT simulator. Materials and Methods: The analysis was performed by the patients who visited the hospital to June 2012. The patient carried out CT-image by CT simulator, and we were plan to compare with a two-dimensional and threedimensional treatment planning using a Oncentra Brachy planning system (Nucletron, Netherland). Results: The location of the catheter was confirmed the each time on a treatment planning for fractionated transbronchial brachytherapy. GTV volumes were $3.5cm^3$ and $3.3cm^3$. Also easy to determine the dose distribution of the tumor, the errors of a dose delivery were confirmed dose distribution of the prescibed dose for GTV. In the first treatment was 92% and the second was 88%. Conclusion: In order to compensate for the problem through a two-dimensional treatment planning, it is necessary to be tested process for the accurate identification and analysis of the treatment volume and dose distribution. Quantitatively determine the dose delivery error process that is reflected to the treatment planning is required.

광유도발광선량계(Optically Stimulated Luminescent Dosimeter)의 선량 특성에 관한 고찰

김정미,전수동,백금문,조영필,윤화룡,권경태,Kim, Jeong-Mi,Jeon, Su-Dong,Back, Geum-Mun,Jo, Young-Pil,Yun, Hwa-Ryong,Kwon, Kyung-Tae 대한방사선치료학회 2010 대한방사선치료학회지 Vol.22 No.2

Purpose: The purpose of this study was to evaluate dosimetric characteristics of Optically stimulated luminescent dosimeters (OSLD) for dosimetry Materials and Methods: InLight/OSL $NanoDot^{TM}$ dosimeters was used including $Inlight^{TM}MicroStar$ Reader, Solid Water Phantom, and Linear accelerator ($TRYLOGY^{(R)}$) OSLDs were placed at a Dmax in a solid water phantom and were irradiated with 100 cGy of 6 MV X-rays. Most irradiations were carried out using an SSD set up 100 cm, $10{\times}10\;cm^2$ field and 300 MU/min. The time dependence were measured at 10 minute intervals. The dose dependence were measured from 50 cGy to 600 cGy. The energy dependence was measured for nominal photon beam energies of 6, 15 MV and electron beam energies of 4-20 MeV. The dose rate dependence were also measured for dose rates of 100-1,000 MU/min. Finally, the PDD was measured by OSLDs and Ion-chamber. Results: The reproducibility of OSLD according to the Time flow was evaluated within ${\pm}2.5%$. The result of Linearity of OSLD, the dose was increased linearly up to about the 300 cGy and increased supralinearly above the 300 cGy. Energy and dose rate dependence of the response of OSL detectors were evaluated within ${\pm}2%$ and ${\pm}3%$. $PDD_{10}$ and PDD20 which were measured by OSLD was 66.7%, 38.4% and $PDD_{10}$ and $PDD_{20}$ which were measured by Ion-chamber was 66.6%, 38.3% Conclusion: As a result of analyzing characteration of OSLD, OSLD was evaluated within ${\pm}3%$ according to the change of the time, enregy and dose rate. The $PDD_{10}$ and $PDD_{20}$ are measured by OSLD and ion-chamber were evaluated within 0.3%. The OSL response is linear with a dose in the range 50~300 cGy. It was possible to repeat measurement many times and progress of the measurement of reading is easy. So the stability of the system and linear dose response relationship make it a good for dosimetry.

종양의 움직임과 호흡주기에 따른 체적 변화에 대한 연구: 팬텀 Study

김민수,백금문,김대섭,강태영,홍동기,권경태,Kim, Min-Su,Back, Geum-Mun,Kim, Dae-Sup,Kang, Tae-Yeong,Hong, Dong-Ki,Kwon, Kyung-Tae 대한방사선치료학회 2010 대한방사선치료학회지 Vol.22 No.2

Purpose: To accurately define internal target volume (ITV) for treatment of moving target considering tumor size and respiratory motion, we quantitatively investigated volume of target volume delineated on CT images from helical CT and 4D CT scans. Materials and Methods: CT images for a 1D moving phantom with diameters of 1.5, 3, and 6 cm, acryl spheres were acquired using a LightSpeed $RT^{16}CT$ simulator. To analyze effect of tumor motion on target delineation, the CT image of the phantoms with various moving distances of 1~4 cm, and respiratory periods of 3~6 seconds, were acquired. For investigating the accuracy of the target trajectory, volume ratio of the target volumes delineated on CT images to expected volumes calculated with diameters of spherical phantom and moving distance were compared. Results: Ratio$_{helical}$ for the diameter of 1, 5, 3, and 6 cm targets were $32{\pm}14%$, $45{\pm}14%$, and $58{\pm}13%$, respectively, in the all cases. As to 4DCT, RatioMIP were $98{\pm}8%$, $97{\pm}5%$, and $95{\pm}1%$, respectively. Conclusion: The target volumes delineated on MIP images well represented the target trajectory, in comparison to those from helical CT. Target volume delineation on MIP images might be reasonable especially for treatment of early stage lung cancer, with meticulous attention to small size target, large respiratory motion, and fast breathing.

Evaluation of the Modulation Transfer Function of Megavoltage X-rays

Jung-Whan Min,Ki-Won Kim,김정민,최인석,정회원,Soon-Yong Son,Geum-Mun Back,정재홍,정재용,최보영 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.11

The modulation transfer function (MTF) must be measured against the requirements of thespecific digital imaging application under consideration in order to evaluate the performance ofdetector equipment and to further develop the detector by performing quality-assurance (QA)procedures. The purpose of this study was to measure the MTF in digital megavoltage images(DMVs) for radiation therapy (RT) by using an edge block. We used 6 megavolts (MVs) of energy forthe pre-sampling MTF, along with a photo-stimulating phosphor-based computed radiography (CR)system and a hexalon lead screen that contained a terbium-doped gadolinium oxysulfide granularphosphor (Gd2O2S:Tb). The DMV MTF was measured at both low and high resolutions accordingto changes in the dose in monitor units (MUs) by using four different detector combinations: CR-IP(image plate: photo-stimulable phosphor screen), CR-IP-Lead (image plate + lead screen), CR-IPRegular(fast front screen + image plate + fast front screen) and CR-IP-Fast (fast back screen +image plate + fast front screen). At a low resolution, the MTF 50% and the MTF 10% when usingthe CR-IP detector increased by about 30% and 46%, in proportion to the increase in the dose from1 to 20 MU, respectively. At a high resolution, the CR-IP and the CR-IP-Lead detectors showedincreases in the MTF of about 8% or 10% when the dose increased from 1 to 20 MU. The presentstudy, therefore, evaluates how edge methods can be helpful in taking MTF measurements duringQA tests of a megavoltage imaging (MVI) system.

비인강암의 치료에서 동시차등조사가속치료를 적용한 제1상/2상 연구의 예비적 결과

박진홍(Jin-hong Park),이상욱(Sang-wook Lee),배금문(Geum Mun Back),이병용(Byong Yong Yi),최은경(Eun Kyung Choi),안승도(Seung Do Ahn),신성수(Seong Soo Shin),김정훈(Jung-hun Kim),김상윤(Sang Yoon Kim),이봉재(Bong-Jae Lee),남순열(Soon-Yu 대한방사선종양학회 2006 Radiation Oncology Journal Vol.24 No.1

목 적: 비인강암 환자를 대상으로 시행한 동시차등조사가속치료(simultaneous modulated accelerated radiation therapy, SMART)를 이용한 세기조절방사선치료(intensity modulated radiation therapy, IMRT)의 예비적 임상결과를 보고하고자 하였다. 대상 및 방법: 2001년 9월부터 2003년 12월까지 서울아산병원에서 근치적 목적의 동시차등조사가속치료를 시행받은 20명의 비전이성 비인강암 환자를 대상으로 전향적 분석을 시행하였다. IMRT는 “step and shoot” SMART를 사용하여 시행되었으며, 각각 육안적종양체적(gross tumor volume, GTV)에 72 Gy (2.4 Gy/day), 비인강과 전이성 림프절부위(metastatic nodal station) 등을 포함하는 임상표적체적 1 (Clinical target volume 1, CTV1)에 60 Gy (2.0 Gy/day), 그리고 임상적으로 전이가 없는 경부 부위림프절을 포함하는 임상표적체적 2 (clinical target volume 2, CTV2)에 46 Gy (2 Gy/day)를 조사하였다. 18명의 환자는 주당 1회의 cisplatin 화학요법을 시행받았다. 결 과: 연구대상에 포함된 환자의 추적관찰 기간의 중앙값은 27개월이었다. 19명의 환자는 치료 중단 없이 계획된 치료를 성공적으로 수행하였으나, 1명은 고도의 인두염과 영양불량으로 2주간 치료가 중단되었다. 치료 기간 중급성 독성은 RTOG 3도의 점막염과 인두염이 각각 5명(25%)과 9명(45%)에서 관찰되었다. 7명(35%)은 10% 이상의 체중 감소를 보였으며 11명(55%)은 정맥수액요법 혹은 경관영양요법을 필요로 하였다. 만성 독성에서 3급 이상의 구강건조증은 관찰되지 않았다. 치료 반응은 모든 환자에서 완전관해를 보였고, 원격전이와 국소재발이 각각 2명과 1명에서 관찰되었다. 결 론: SMART를 사용한 IMRT를 도입하여 임상적으로나 선량측정상 이하선의 기능 보존이 가능하였으며, 또한 생물학적으로 더욱 효과적일 것으로 생각되었다. 향후 정확한 종양억제 효과와 만기 독성을 알기 위해서는 추가적인 연구대상과 추적관찰이 필요하다고 생각한다. Purpose: To present preliminary results of intensity-modulated radiotherapy (IMRT) using the simultaneous modulated accelerated radiation therapy (SMART) boost technique in patients with nasopharyngeal carcinoma (NPC). Materials and Methods: Twenty patients who underwent IMRT for non-metastatic NPC at the Asan Medical Center between September 2001 and December 2003 were prospectively evaluated. IMRT was delivered using the “step and shoot” SMART technique at prescribed doses of 72 Gy (2.4 Gy/day) to the gross tumor volume (GTV), 60 Gy (2 Gy/day) to the clinical target volume (CTV) and metastatic nodal station, and 46 Gy (2 Gy/day) to the clinically negative neck region. Eighteen patients also received concurrent chemotherapy using cisplatin once per week. Results: The median follow-up period was 27 months. Nineteen patients completed the treatment without interruption; the remaining patient interrupted treatment for 2 weeks owing to severe pharyngitis and malnutrition. Five patients (25%) had RTOG grade 3 mucositis, whereas nine (45%) had grade 3 pharyngitis. Seven patients (35%) lost more than 10% of their pretreatment weight, whereas 11 (55%) required intravenous fluids and/or tube feeding. There was no grade 3 or 4 chronic xerostomia. All patients showed complete response. Two patients had distant metastases and loco-regional recurrence, respectively. Conclusion: IMRT using the SMART boost technique allows parotid sparing, as shown clinically and by dosimetry, and may also be more effective biologically. A larger population of patients and a longer follow-up period are needed to evaluate ultimate tumor control and late toxicity.