• Radiation Oncology Journal
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• 제36권1호
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• pp.71-78
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• 2018

Purpose: To compare the dose distribution of three-dimensional conformal radiation therapy (3DCRT) with intensity-modulated radiation therapy (IMRT) for post-mastectomy radiotherapy (PMRT) to left chest wall. Materials and Methods: One hundred and seven patients were randomised for PMRT in 3DCRT group (n = 64) and IMRT group (n = 43). All patients received 50 Gy in 25 fractions. Planning target volume (PTV) parameters-$D_{near-max}$ ($D_2$), $D_{near-min}$ ($D_{98}$), $D_{mean}$, $V_{95}$, and $V_{107}$-homogeneity index (HI), and conformity index (CI) were compared. The mean doses of lung and heart, percentage volume of ipsilateral lung receiving 5 Gy ($V_5$), 20 Gy ($V_{20}$), and 55 Gy ($V_{55}$) and that of heart receiving 5 Gy ($V_5$), 25 Gy ($V_{25}$), and 45 Gy ($V_{45}$) were extracted from dose-volume histograms and compared. Results: PTV parameters were comparable between the two groups. CI was significantly improved with IMRT (1.127 vs. 1.254, p < 0.001) but HI was similar (0.094 vs. 0.096, p = 0.83) compared to 3DCRT. IMRT in comparison to 3DCRT significantly reduced the high-dose volumes of lung ($V_{20}$, 22.09% vs. 30.16%; $V_{55}$, 5.16% vs. 10.27%; p < 0.001) and heart ($V_{25}$, 4.59% vs. 9.19%; $V_{45}$, 1.85% vs. 7.09%; p < 0.001); mean dose of lung and heart (11.39 vs. 14.22 Gy and 4.57 vs. 8.96 Gy, respectively; p < 0.001) but not the low-dose volume ($V_5$ lung, 61.48% vs. 51.05%; $V_5$ heart, 31.02% vs. 23.27%; p < 0.001). Conclusions: For left sided breast cancer, IMRT significantly improves the conformity of plan and reduce the mean dose and high-dose volumes of ipsilateral lung and heart compared to 3DCRT, but 3DCRT is superior in terms of low-dose volume.

• Radiation Oncology Journal
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• 제35권3호
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• pp.249-256
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• 2017

Purpose: We retrospectively reviewed the results of radiotherapy for localized ocular adnexal MALT lymphoma (OAML) to investigate the risk factors of cataract. Methods: Sixty-seven patients with stage IE OAML treated with radiotherapy at Seoul St. Mary's Hospital from 2001 to 2016 were included. Median treatment dose was 30 Gy. Lens protection was done in 52 (76%) patients. Radiation therapy (RT) extent was as follows: superficial (82.1%), tumor mass (4.5%), and entire orbital socket (13.4%). The risk factors for symptomatic cataract were analyzed using the Cox proportional hazard model. Results: Median follow-up time was 50.9 months (range, 1.9 to 149.4 months). All patients were alive at the time of analysis. There were 7 recurrences and there was no local recurrence. Median time to recurrence was 40.4 months. There were 14 cases of symptomatic cataract. Dose >30 Gy had hazard ratio of 3.47 for cataract (p = 0.026). Omitting lens protection showed hazard ratio of 4.10 (p = 0.008). Conclusions: RT achieves excellent local control of ocular MALT lymphoma. Consideration of RT-related factors such as lens protection and radiation dose at the stage of RT planning may reduce the risk of RT-induced cataract after radiotherapy.

• Radiation Oncology Journal
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• 제36권1호
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• pp.63-70
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• 2018

Purpose: The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. Materials and Methods: We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Results: Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart $V_{30}$ (p = 0.039), $V_{40}$ (p = 0.040), and $V_{50}$ (p = 0.032). Conclusion: Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung $V_{10}$, $V_{20}$, and $V_{30}$ than in 3D-CRT, but could not be proven superior in lung $V_5$. In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

• 대한방사선치료학회지
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• 제18권2호
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• pp.67-73
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• 2006

목 적: 암 환자의 증가와 함께 방사선 치료기술도 날로 발전하고 있으며 이로인해 치료를 위해 사용되는 영상 및 데이터의 양들도 대폭 증가하는 결과를 가져오게 되어 이들을 저장, 보관, 관리하는데 많은 어려움이 있었다. 이러한 문제점 해결을 위해 과에서 발생되는 모든 영상 및 data의 PACS (picture archiving and communication system)화를 목적으로 의료정보팀의 협조 하에 본 System을 개발, 적용하게 되었다. 대상 및 방법: 본과 방사선치료 관리 시스템(RO-radiation oncology)에서 PACS에 접근할 수 있는 code를 부여한 후 영상은 R&V (Record and Verify: Varis vision, Varian, USA) 시스템 및 planning system에서 export 한다. 이때 DICOM (digital image and communication system) head에 있는 많은 정보들 중에서 필요한 정보를 이용하여 프로그램화 하였다. 결 과: 방사선종양학과에서 발생되는 모든 영상 및 자료 즉, 모의치료, CT, L-gram 영상, structure (normal organ & target volume), DRR (Digital Reconstruction Radiography), 선량 분포도, DVH (dose volume histogram) 등을 PACS에 구현 하였으며 과내 어느 컴퓨터에서도 선명히 영상을 볼 수 있고 출력할 수 있도록 하였다. 결 론: 본 시스템의 개발로 film less화가 가능하게 되어 현상 처리에 관련한 암실 공간과 유지비용이 소멸되었고 film 저장공간 및 film을 찾는데 소요되는 인력과 시간을 포함한 유, 무형의 경제적 비용뿐만 아니라 영상 저장을 위한 별도의 저장장치의 구입도 불필요하게 되었다. 아울러 방사선 치료를 위해 복잡하게 행해졌던 일련의 과정들이 본 시스템을 통해서 현재는 전산 상에서 쉽게 처리할 수 있게 되어 업무에 많은 도움이 될 것으로 사료된다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권17호
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• pp.7785-7788
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• 2015

Utilization of high energy photons (>10MV) with an optimal weight using a mixed energy technique is a practical way to generate a homogenous dose distribution while maintaining adequate target coverage in intact breast radiotherapy. This study represents a model for estimation of this optimal weight for day to day clinical usage. For this purpose, treatment planning computed tomography scans of thirty-three consecutive early stage breast cancer patients following breast conservation surgery were analyzed. After delineation of the breast clinical target volume (CTV) and placing opposed wedge paired isocenteric tangential portals, dosimeteric calculations were conducted and dose volume histograms (DVHs) were generated, first with pure 6MV photons and then these calculations were repeated ten times with incorporating 18MV photons (ten percent increase in weight per step) in each individual patient. For each calculation two indexes including maximum dose in the breast CTV ($D_{max}$) and the volume of CTV which covered with 95% Isodose line ($V_{CTV,95%IDL}$) were measured according to the DVH data and then normalized values were plotted in a graph. The optimal weight of 18MV photons was defined as the intersection point of $D_{max}$ and $V_{CTV,95%IDL}$ graphs. For creating a model to predict this optimal weight multiple linear regression analysis was used based on some of the breast and tangential field parameters. The best fitting model for prediction of 18MV photons optimal weight in breast radiotherapy using mixed energy technique, incorporated chest wall separation plus central lung distance (Adjusted R2=0.776). In conclusion, this study represents a model for the estimation of optimal beam weighting in breast radiotherapy using mixed photon energy technique for routine day to day clinical usage.

• Radiation Oncology Journal
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• 제36권3호
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• pp.241-247
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• 2018

Purpose: A hybrid-dynamic conformal arc therapy (HDCAT) technique consisting of a single half-rotated dynamic conformal arc beam and static field-in-field beams in two directions was designed and evaluated in terms of dosimetric benefits for radiotherapy of lung cancer. Materials and Methods: This planning study was performed in 20 lung cancer cases treated with the VERO system (BrainLAB AG, Feldkirchen, Germany). Dosimetric parameters of HDCAT plans were compared with those of three-dimensional conformal radiotherapy (3D-CRT) plans in terms of target volume coverage, dose conformity, and sparing of organs at risk. Results: HDCAT showed better dose conformity compared with 3D-CRT (conformity index: 0.74 ± 0.06 vs. 0.62 ± 0.06, p < 0.001). HDCAT significantly reduced the lung volume receiving more than 20 Gy (V₂₀: 21.4% ± 8.2% vs. 24.5% ± 8.8%, p < 0.001; V₃₀: 14.2% ± 6.1% vs. 15.1% ± 6.4%, p = 0.02; V₄₀: 8.8% ± 3.9% vs. 10.3% ± 4.5%, p < 0.001; and V₅₀: 5.7% ± 2.7% vs. 7.1% ± 3.2%, p < 0.001), V₄₀ and V₅₀ of the heart (V₄₀: 5.2 ± 3.9 Gy vs. 7.6 ± 5.5 Gy, p < 0.001; V₅₀: 1.8 ± 1.6 Gy vs. 3.1 ± 2.8 Gy, p = 0.001), and the maximum spinal cord dose (34.8 ± 9.4 Gy vs. 42.5 ± 7.8 Gy, p < 0.001) compared with 3D-CRT. Conclusions: HDCAT could achieve highly conformal target coverage and reduce the doses to critical organs such as the lung, heart, and spinal cord compared to 3D-CRT for the treatment of lung cancer patients.

• 한국의학물리학회지:의학물리
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• 제34권1호
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• pp.1-9
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• 2023

Purpose: Although ionization chambers are widely used to measure beam commissioning data, point-by-point measurements of all the profiles with various field size and depths are time-consuming tasks. As an alternative, we investigated the feasibility of a linear diode array for commissioning a treatment planning system. Methods: The beam data of a Varian TrueBeam^® radiotherapy system at 6 and 10 MV with/without a flattening filter were measured for commissioning of an Eclipse Analytical Anisotropic Algorithm (AAA) ver.15.6. All of the necessary beam data were measured using an IBA CC13 ionization chamber and validated against Varian "Golden Beam" data. After validation, the measured CC13 profiles were used for commissioning the Eclipse AAA (AAA_CC13). In addition, an IBA LDA-99SC linear diode array detector was used to measure all of the beam profiles and for commissioning a separate model (AAA_LDA99). Finally, the AAA_CC13 and AAA_LDA99 dose calculations for each of the 10 clinical plans were compared. Results: The agreement of the CC13 profiles with the Varian Golden Beam data was confirmed within 1% except in the penumbral region, where ≤2% of a discrepancy related to machine-specific jaw calibration was observed. Since the volume was larger for the CC13 chamber than for the LDA-99SC chamber, the penumbra widths were larger in the CC13 profiles, resulting in ≤5% differences. However, after beam modeling, the penumbral widths agreed within 0.1 mm. Finally the AAA_LDA99 and AAA_CC13 dose distributions agreed within 1% for all voxels inside the body for the 10 clinical plans. Conclusions: In conclusion, the LDA-99SC diode array detector was found to be accurate and efficient for measuring photon beam profiles to commission treatment planning systems.

• 한국의학물리학회지:의학물리
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• 제30권4호
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• pp.150-154
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• 2019

The objective of this study is to monitor the radiation doses delivered to a cardiac implantable electronic device (CIED) by comparing the absorbed doses calculated by a commercial treatment planning system (TPS) to those measured by an in vivo dosimeter. Accurate monitoring of the radiation absorbed by a CIED during radiotherapy is necessary to prevent damage to the device. We conducted this study on three patients, who had the CIED inserted and were to be treated with radiotherapy. Treatment plans were generated using the Eclipse system, with a progressive resolution photon optimizer algorithm and the Acuros XB dose calculation algorithm. Measurements were performed on the patients using optically stimulated luminescence detectors placed on the skin, near the CIED. The results showed that the calculated doses from the TPS were up to 5 times lower than the measured doses. Therefore, it is recommended that in vivo dosimetry be conducted during radiotherapy for CIED patients to prevent damage to the CIED.

• 대한방사선기술학회지:방사선기술과학
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• 제42권6호
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• pp.413-422
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• 2019

Heavy ion particle, represented carbon ion, radiotherapy is currently most advanced radiation therapy technique. Conventional radiation therapy has made remarkable changes over a relatively short period of time and leading various developments such as intensity modulated radiation therapy, 4D radiation therapy, image guided radiation therapy, and high precisional therapy. However, the biological and physical superiority of particle radiation, represented by Bragg peak, can give the maximum dose to tumor and minimal dose to surrounding normal tissues in the treatment of cancers in various areas surrounded by radiation-sensitive normal tissues. However, despite these advantages, there are some limitations and factors to consider. First, there is not enough evidence, such as large-scale randomized, prospective phase III trials, for the clinical application. Secondly, additional studies are needed to establish a very limited number of treatment facilities, uncertainty about the demand for heavy particle treatment, parallel with convetional radiotherapy or indications. In addition, Bragg peak of the heavy particles can greatly reduce the dose to the normal tissues front and behind the tumor compared to the photon or protons. High precision and accuracy are needed for treatment planning and treatment, especially for lungs or livers with large respiratory movements. Currently, the introduction of the heavy particle therapy device is in progress, and therefore, it is expected that more research will be active.

• International Journal of Contents
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• 제13권4호
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• pp.12-15
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• 2017

Among the possible stereotactic body radiation therapy (SBRT) modalities used to treat patients with metastatic spinal tumors, this study compared Cyberknife, tomotherapy, and volumetric modulated arc radiotherapy (VMAT). We established treatment plans for each of them modality and quantitatively analyzed the dose evaluation factors of the dose-volume histogram (DVH) for all spinal bones, focusing on the tumor and spinal cord, in order to examine the usefulness of VMAT. For the treatment planning dose, the mean dose ($D_{max}$) and $D_{5%}$ showed statistical differences in the target dose, but no difference was shown in the spinal cord dose. For the DVH indices, tomotherapy showed the best performance was the best in terms of uniformity index, while VMAT showed better performance was better than the other two modalities in terms of the conformity index and the dose gradient index. VMAT had a much shorter treatment time than Cyberknife and tomotherapy. These findings suggest that VMAT FFF is the most effective therapy for SBRT of patients with metastatic spinal tumors for whom a high dose of radiation is prescribed.