• Radiation Oncology Journal
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• 제28권1호
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• pp.39-49
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• 2010

목 적: 좌측 유방의 방사선치료에 있어, 3 빔 또는 5 빔을 이용한 세기변조방사선치료(intensity modulated radiation therapy, IMRT)와 다중빔조사영역 치료기법(multistatic fields techniques, MSF) 사이의 선량학적 차이를 분석하고자 하였다. 대상 및 방법: 개선된 선량 균일성을 만들 수 있는 가능성을 지닌 두 종류의 방사선치료 기술을 서로 비교 분석하였다. 첫째, 다중빔조사영역치료로 주조사야와 소조사야를 동시에 사용하여 치료하였다. 둘째, 고정된 다엽 조준기를 사용하는 IMRT로, 3 빔 또는 5 빔을 이용하였다. 유방보존술 후 방사선치료를 받은 16명의 초기 좌측 유방암 환자들을 대상으로 방사선치료계획들을 세운 다음, 이들을 선량학적 측면에서 비교 분석하였다. 결 과: $V_{95}$와 선량균일지수의 평균값은, 이 세 치료 사이에 통계학적으로 유의한 차이가 없었다. 방사선처방선량의 110% 이상을 받는 극심한 열점은 세 치료 모두에서 관찰되지 않았다. 동측 폐와 심장의 피폭 선량측정인자들에 대한 Tukey 검정에서, 세기변조방사선치료가 다중빔조사영역치료에 비해 저선량 영역의 피폭 선량을 유의하게 증가시킨 반면, 오히려 고선량 영역에서는 다중빔조사영역치료가 방사선 피폭을 약간 증가시켰다. 결 론: 선량 균일성 개선을 위해, 통상적인 쐐기기법 대신, 세기변조방사선치료보다 쉽게 계획되고 실시 될 수 있는 다중빔조사영역치료의 적용은 초기 좌측 유방암의 방사선치료 기술로 적합하다고 생각한다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.248-251
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• 2002

The intensity modulated radiation therapy (IMRT) with a multileaf collimator (MLC) requires the conversion of a radiation fluence map into a leaf sequence file that controls the movement of the MLC during radiation treatment of patients. Patient dose verification is clinically one of the most important parts in the treatment delivery of the radiation therapy. The three dimensional (3D) reconstruction of dose distribution delivered to the target helps to verify patient dose and to determine the physical characteristics of beams used in IMRT. A new method is presented for the pretreatment dosimetric verification of two dimensional distributions of photon intensity by means of Beam Intensity Scanner System (BISS) as a radiation detector with a custom-made software for dose calculation of fluorescence signals from scintillator. The scintillator is used to produce fluorescence from the irradiation of 6MV photons on a Varian Clinac 21EX. The BISS reproduces 3D- relative dose distribution from the digitized fluoroscopic signals obtained by digital video camera-based scintillator(DVCS) device in the IMRT. For the intensity modulated beams (IMBs), the calculations of absorbed dose are performed in absolute beam fluence profiles which are used for calculation of the patient dose distribution. The 3D-dose profiles of the IMBs with the BISS were demonstrated by relative measurements of photon beams and shown good agreement with radiographic film. The mechanical and dosimetric properties of the collimating of dynamic and/or step MLC system alter the generated intensity. This is mostly due to leaf transmission, leaf penumbra and geometry of leaves. The variations of output according to the multileaf opening during the irradiation need to be accounted for as well. These phenomena result in a fluence distribution that can be substantially different from the initial and calculative intensity modulation and therefore, should be taken into account by the treatment planning for accurate dose calculations delivered to the target volume in IMRT.

• Radiation Oncology Journal
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• 제34권2호
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• pp.145-155
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• 2016

Purpose: Radiation therapy targeting axilla and groin lymph nodes improves regional disease control in locally advanced and high-risk skin cancers. However, trials generally used conventional two-dimensional radiotherapy (2D-RT), contributing towards relatively high rates of side effects from treatment. The goal of this study is to determine if three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), or volumetric-modulated arc therapy (VMAT) may improve radiation delivery to the target while avoiding organs at risk in the clinical context of skin cancer regional nodal irradiation. Materials and Methods: Twenty patients with locally advanced/high-risk skin cancers underwent computed tomography simulation. The relevant axilla or groin planning target volumes and organs at risk were delineated using standard definitions. Paired t-tests were used to compare the mean values of several dose-volumetric parameters for each of the 4 techniques. Results: In the axilla, the largest improvement for 3D-CRT compared to 2D-RT was for homogeneity index (13.9 vs. 54.3), at the expense of higher lung $V_{20}$ (28.0% vs. 12.6%). In the groin, the largest improvements for 3D-CRT compared to 2D-RT were for anorectum $D_{max}$ (13.6 vs. 38.9 Gy), bowel $D_{200cc}$ (7.3 vs. 23.1 Gy), femur $D_{50}$ (34.6 vs. 57.2 Gy), and genitalia $D_{max}$ (37.6 vs. 51.1 Gy). IMRT had further improvements compared to 3D-CRT for humerus $D_{mean}$ (16.9 vs. 22.4 Gy), brachial plexus $D_5$ (57.4 vs. 61.3 Gy), bladder $D_5$ (26.8 vs. 36.5 Gy), and femur $D_{50}$ (18.7 vs. 34.6 Gy). Fewer differences were observed between IMRT and VMAT. Conclusion: Compared to 2D-RT and 3D-CRT, IMRT and VMAT had dosimetric advantages in the treatment of nodal regions of skin cancer patients.

• 한국의학물리학회지:의학물리
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• 제32권4호
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• pp.83-91
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• 2021

Various types of high-precision radiotherapy, such as intensity-modulated radiation therapy (IMRT), tomotherapy (Tomo), and stereotactic body radiation therapy have been available since 1997. After being covered by insurance in 2015, the number of IMRT cases rapidly increased 18-fold from 2011 to 2018 in Korea. IMRT, which uses a high-beam irradiation monitor unit, requires higher shielding conditions than conventional radiation treatments. However, to date, research on the shielding of facilities using IMRT and the current understanding of its status are insufficient, and detailed safety regulation procedures have not been established. This study investigated the recommended criteria for the shielding evaluation of facilities using medical linear accelerators (LINACs), including 1) the current status of safety management regulations and systems in domestic and international facilities using medical LINACs and 2) the current status of the recommended standards for safety management in domestic and international facilities using medical LINACs. It is necessary to develop and introduce a safety management system for facilities using LINACs for clinical applications that is suitable for the domestic medical environment and corresponds to the safety management systems for LINACs used overseas.

• 대한방사선치료학회지
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• 제34권
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• pp.7-12
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• 2022

목 적: 볼루스 적용이 어려운 코와 같은 요철 부위 치료 시 피부 선량 확보에 어려움이 있는 경우, IMRT(Intensity Modulated Radiation Therapy)전달 기법 과 평균 에너지가 낮은 FFF(Flattening Filter Free)를 조합한 치료 계획으로 피부 선량 증가 여부를 팬텀 실험을 통해 알아보고자 하였다. 대상 및 방법: 두경부암 치료시 가장 흔하게 사용하는 6MV-FF(Flattening Filter) VMAT(Volumetric-Modulated Arc Therapy) 치료계획을 기준으로 정하고, VMAT와 IMRT, FF와 FFF, 5 mm 볼루스 적용 유무를 조합하여 비교군을 생성하였다. 란도 팬텀 콧등에 가상 타겟을 생성하였고, 5 mm 의 가상의 볼루스를 란도 팬텀 콧등 위에 완전 밀착을 가정하여 적용하였다. 팬텀의 코를 기준으로 5개 측정지점을 정하고 각각의 치료계획 을 치료테크닉과 bolus 적용유무에 맞게 치료계획 당 3회를 조사하여 흡수선량을 측정하였다. 결 과: FF vs FFF 에서의 피부선량 차이는 VMAT bolus off에서 FFF인 경우 증가하였고, IMRT bolus off의 경우 차이를 나타내지 않았다. VMAT bolus 5 mm, IMRT bolus 5 mm에서는 FFF에서 오히려 피부선량이 감소되는 것을 확인 할 수 있었다. VMAT vs IMRT 피부선량 차이는 FFF bolus off 의 경우에만 피부선량이 증가했고, 나머지는 통계적 차이가 없었다. bolus off vs bolus 5 mm 에서의 피부선량 차이는 IMRT FFF 을 사용했을 경우만 제외하고는 모두 bolus 5 mm 에서 피부선량이 증가하는 것을 확인하였다. IMRT와 FFF를 조합한 치료 계획은 통상적으로 사용되는 VMAT와 FF를 사용하여 5 mm 볼루스를 적용한 치료 계획 피부선량의 측정값을 분석한 결과 통계적으로 유의미한 차이를 발견하지 못했다. 따라서 IMRT_FFF 를 사용함으로써 VMAT_FF 에 5 mm 볼루스 적용한 것과 비슷한 수준의 피부선량 전달이 가능할 것이라 사료되며, 이는 높은 피부선량이 필요하지만, 볼루스 적용이 어려운 환자와 같은 경우에 유용할 수 있다. 결 론: 볼루스 적용이 어려운 환자의 경우, VMAT와 FF에 비교하여 IMRT와 FFF를 적절히 조합한 치료 계획으로 피부 선량 증가를 기대할 수 있다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권8호
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• pp.3257-3265
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• 2015

Background: Radiotherapy is an important treatment of choice for breast cancer patients after breast-conserving surgery, and we compare the feasibility of using dual arc volumetric modulated arc therapy (VMAT2), single arc volumetric modulated arc therapy (VMAT1) and Multi-beam Intensity Modulated Radiotherapy (M-IMRT) on patients after breast-conserving surgery. Materials and Methods: Thirty patients with breast cancer (half right-sided and half left-sided) treated by conservative lumpectomy and requiring whole breast radiotherapy with tumor bed boost were planned with three different radiotherapy techniques: 1) VMAT1; 2) VMAT2; 3) M-IMRT. The distributions for the planning target volume (PTV) and organs at risk (OARs) were compared. Dosimetries for all the techniques were compared. Results: All three techniques satisfied the dose constraint well. VMAT2 showed no obvious difference in the homogeneity index (HI) and conformity index (CI) of the PTV with respect to M-IMRT and VMAT1. VMAT2 clearly improved the treatment efficiency and can also decrease the mean dose and V5Gy of the contralateral lung. The mean dose and maximum dose of the spinal cord and contralateral breast were lower for VMAT2 than the other two techniques. The very low dose distribution (V1Gy) of the contralateral breast also showed great reduction in VMAT2 compared with the other two techniques. For the ipsilateral lung of right-sided breast cancer, the mean dose was decreased significantly in VMAT2 compared with VMAT1 and M-IMRT. The V20Gy and V30Gy of the ipsilateral lung of the left-sided breast cancer for VMAT2 showed obvious reduction compared with the other two techniques. The heart statistics of VMAT2 also decreased considerably compared to VMAT1 and M-IMRT. Conclusions: Compared to the other two techniques, the dual arc volumetric modulated arc therapy technique reduced radiation dose exposure to the organs at risk and maintained a reasonable target dose distribution.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2003년도 제27회 추계학술대회
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• pp.64-64
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• 2003

Objectives: Patient dose verification is clinically the most important parts in the treatment delivery of radiation therapy. The three dimensional(3D) reconstruction of dose distribution delivered to target volume helps to verify patient dose and determine the physical characteristics of beams used in intensity modulated radiation therapy(IMRT). We present Beam Intensity Scanner(BInS) system for the pre treatment dosimetric verification of two dimensional photon intensity. The BInS is a radiation detector with a custom made software for relative dose conversion of fluorescence signals from scintillator. Methods: This scintillator is fabricated by phosphor Gadolinium Oxysulphide and is used to produce fluorescence from the irradiation of 6MV photons on a Varian Clinac 21EX. The digitized fluoroscopic signals obtained by digital video camera will be processed by our custom made software to reproduce 3D relative dose distribution. For the intensity modulated beam(IMB), the BInS calculates absorbed dose in absolute beam fluence, which are used for the patient dose distribution. Results: Using BInS, we performed various measurements related to IMRT and found the followings: (1) The 3D dose profiles of the IMBs measured by the BInS demonstrate good agreement with radiographic film, pin type ionization chamber and Monte Carlo simulation. (2) The delivered beam intensity is altered by the mechanical and dosimetric properties of the collimating of dynamic and/or static MLC system. This is mostly due to leaf transmission, leaf penumbra, scattered photons from the round edges of leaves, and geometry of leaf. (3) The delivered dose depends on the operational detail of how to make multileaf opening. Conclusions: These phenomena result in a fluence distribution that can be substantially different from the initial and calculative intensity modulation and therefore, should be taken into account by the treatment planing for accurate dose calculations delivered to the target volume in IMRT.

• 대한방사선치료학회지
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• 제33권
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• pp.89-97
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• 2021

목 적: 본 연구에서는 자궁경부암 방사선치료 시 전산화치료계획에 없던 직장 내 가스 용적 변화에 따른 선량변화를 비교 평가하고자 한다. 대상 및 방법: 인체모형 팬텀(Anderson Research Laboratories Inc, RANDO^TM phantom, USA)의 전산화 단층촬영 영상에 전산화치료계획시스템(Eclipse^TM Treatment Planning System, Varian, Palo Alto, version 15.6, USA)으로 9개의 필드를 이용한 정적 세기조절방사선치료계획(Static Intensity Modulated Radiation Therapy, S-IMRT)과 Full arc로 두 방향의 체적변조회전방사선치료계획(Volumetric Modulated Arc Therapy, VMAT)을 수립하였다. 임의의 가스 변수는 0.5 cm 단위로 2.0 cm까지 변화를 주어 계획표적체적(Planning Target Volume, PTV)에 포함될 수 있도록 하였다. 표적에 대한 처방선량지수(Conformity Index, CI), 선량균질지수(Homogeneity Index, HI), PTV D_max를 구하였고, 손상위험장기(Organ At Risk, OAR)에 대한 최소선량(Minimum Dose, D_min)과 평균선량((Mean Dose, D_mean), 최대선량(Maximum Dose, D_max)을 계산하여 비교하였다. T-검정을 실시하여 p-value를 구했으며 유의수준은 0.05로 설정하였다. 결 과: S-IMRT와 VMAT의 HI 결정계수(R²)는 0.9423, 0.8223으로 상관관계가 비교적 명확하였고, PTV D_max 결과 임의의 가스 용적이 커질수록 최대 2.8%까지 증가하는 것으로 나타났다. OAR의 경우 두 전산화치료계획 모두 방광에서 유의한 차이가 없었고, 직장의 경우 +1.0 cm 이상의 가스 용적에서 두 전산화치료계획 모두 D_mean 700 cGy 이상의 유의한 선량 차이가 나타났다. 방광의 D_mean을 제외한 모든 값에서 p-value 0.05 이하로 통계적인 유의한 차이를 확인하였다. 결 론: 기준 전산화치료계획에 없던 가스 발생 시 가스 용적 크기가 커질수록 PTV의 선량 변화와 직장에 전달되는 선량이 증가하였다. 방사선치료 진행 시 직장 가스의 용적이 클 경우 발생 할 수 있는 선량 전달 오류를 최소화하기 위한 노력이 반드시 필요한 것으로 판단되었다. 향후 가스 용적의 다양한 크기와 위치를 변수로 설정하여 추가적인 연구가 진행되어진다면 유익한 평가가 이루어 질 수 있을 것으로 사료된다.

• Radiation Oncology Journal
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• 제35권4호
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• pp.368-379
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• 2017

Purpose: The purpose of this study was to explore the dosimetric difference between simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) and three-dimensional conformal radiotherapy (3DCRT), and the clinical outcomes of anal squamous cell carcinoma (ASCC) chemoradiotherapy featuring SIB-IMRT. Materials and Methods: This study included ten patients with ASCC who underwent chemoradiotherapy using SIB-IMRT with 5-fluorouracil and mitomycin C. SIB-IMRT delivered 54 Gy to each primary tumor plus metastatic lymph nodes and 45 Gy to regional lymph nodes, in 30 fractions. Four patients received additional boosts to the primary tumors and metastatic lymph nodes; the median total dose was 54 Gy (range, 54 to 60 Gy). We additionally created 3DCRT plans following the Radiation Therapy Oncology Group 9811 protocol to allow dosimetric comparisons with SIB-IMRT. Locoregional control, overall survival, and toxicity were calculated for the clinical outcome evaluation. Results: Compared to 3DCRT, SIB-IMRT significantly reduced doses to the external genitalia, bladder, and intestine, delivering the doses to target and elective nodal region. At a median follow-up time of 46 months, 3-year locoregional control and overall survival rates were 88.9% and 100%, respectively. Acute toxicities were treated conservatively. All patients completed radiotherapy with brief interruptions (range, 0 to 2 days). No patient experienced ${\geq}grade$ 3 late toxicity during the follow-up period. Conclusion: The dosimetric advantages of SIB-IMRT appeared to reduce the toxicity of chemoradiotherapy for ASCC achieving high locoregional control in the extended period.

• 한국콘텐츠학회논문지
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• 제14권8호
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• pp.225-232
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• 2014

전유방절제술을 시행하고 방사선치료시 조사야에 흉벽과 IMNs이 포함되어 심장과 동측 폐에 고선량의 방사선이 흡수되어 만성이환율에 영향을 미칠 수 있다. 따라서 본 연구에서는 전유방절제술을 시행한 유방암 환자의 방사선 치료시 IMRT와 VMAT 기법을 이용하여 선량분포양상을 비교하고자 한다. 유방암 진단을 받고 전유방절제술과 방사선 치료를 시행 받은 환자 중 PTV내에 IMNs가 포함되는 10명의 환자를 선택하여 환자의 흉벽조직, SCL, IMNs을 포함하여 각각 IMRT와 VMAT를 이용하여 치료계획을 실시한 후 PTV의 일치성과 심장 및 폐에 입사되는 선량을 서로 비교하고자 하였다. 그 결과 IMRT와 VMAT에서 모두 PTV의 일치성은 동일 양상(p<0.05)을 보였으며, 좌측유방암 환자인 경우 심장의 고선량 영역은 VMAT이 더 적은 체적으로 관찰(p<0.05)되었다. 폐선량의 경우 IMRT 보다 VMAT시 선량이 더 적게 관찰(p<0.05)되었다. IMNs을 포함하여 치료하는 경우 VMAT가 IMRT보다 방사선 치료 효율이 높을 것으로 사료된다.