• Radiation Oncology Journal
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• v.1 no.1
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• pp.55-60
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• 1983

To evaluate the usefulness of computed tomography (CT) in radiotherapy treatment planning in malignant tumors of thoracic cage, the computer generated dose distributions were compared between plans based on conventional studies and those based on CT scan. 22 cases of thoracic malignancies, 15 lung cancers and 7 esophageal cancers, diagnosed and treated in Department of Therapeutic Radiology of Seoul National University Hospital from September, 1982 to April, 1983, were analyzed. In lung cancers, dose distribution in plans using AP, PA parallel opposing ports with posterior spinal cord block and in plans using box technique both based on conventional studies were compared with dose distribution using AP, PA and two oblique ports based on CT scan. In esophageal cancers, dose distribution in plans based on conventional studies and those based on CT scans, both using 3 port technique were compared. The results are as follows: 1. Parallel opposing field technique were inadequate in all cases of lung cancers, as portion of primary tumor in 13 of 15 cases and portion of mediastinum in all were out of high dose volume. 2. Box technique was inadequate in 5 of 15 lung cancers as portion of primary tumor was not covered and in every case the irradiated normal lung volume was quite large. 3. Plans based on CT scan were superior to those based on conventional studies as tumor was demarcated better with CT and so complete coverage of tumor and preservation of more normal lung volume could be made. 4. In 1 case of lung cancer, tumor localization was nearly impossible with conventional studies, but after CT scan tumor was more clearly defined and localized. 5. In 1 of 7 esophageal cancers, the radiation volume should be increased for marginal coverage after CT scan. 6. Depth dose correction for tissue inhomogeneity is possible with CT, and exact tumor dose can be calculated. As a result radiotherapy treatment planning based on CT scan has a pteat advantage over that based on conventional studies.

• Progress in Medical Physics
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• v.23 no.2
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• pp.99-105
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• 2012

We investigated the influence of photon energy, couch and collimator angle differences between arcs on dose distribution of RapidArc treatment planning for prostate cancer. RapidArc plans were created for 6 MV and 10 MV photons using 2 arcs coplanar and noncoplanar fields. The collimator angle differences between two arcs were $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$. The plans were optimized using same dose constrains for target and OAR (organ at risk). To evaluate the dose distribution, plans were analyzed using CI (conformity index), HI (homogeneity index), QOC (quality of coverage), etc. Photon energy, couch and collimator angle differences between arcs had a little influence on the target and OAR. The difference of dosimetric indices was less than 3.6% in the target and OAR. However, there was significant increase in the region exposed to low dose. The increase of V15% in the femur was 6.4% (left) and 5.5% (right) for the 6 MV treatment plan and 23.4% (left), 24.1% (right) for the noncoplanar plan. The increase of V10% in the Far Region distant from target was 54.2 cc for the 6 MV photon energy, 343.4 cc for the noncoplanar and 457.8 cc for the no collimator rotation between arcs.

• Progress in Medical Physics
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• v.20 no.2
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• pp.112-118
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• 2009

The source position and source dwelling time in a given source arrangement in the applicators is very high effect to determine the expose time which in general is derived from the brachytherapy planning system. In high dose rate (HDR) intracavitary radiation therapy (ICRT), the treatment is often performed in based out-patient during the whole fractionation irradiations. However, the patient should be waited on coutch for ICR treatment in first start fraction as unconvinent and immobilized state until perform the dose plannings. In our experiments, the HDR source contributed dose for$55.89{\pm}4.20%$ for straight tandem source, $38.14{\pm}4.46%$ for the right ovoid soucre on the fornix and$5.97{\pm}0.50%$ for left ovoid source. It also showed the $60.33{\pm}6.53%$ for the tandem, $33.10{\pm}6.74%$ for right ovoid and $6.58{\pm}0.30%$ for the left ovoid source in 10 degrees of applicator. The authors designed the source template dose planning software for ICRT of uterine cervix results average $-0.55{\pm}2.15%$ discrepancy of the full charged brachytherapy dose planning. Developed Source temperate ICRT plaanning software guide a minimized the complains and operating times within a ${\pm}3%$ of dose discrepancies.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.175-181
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• 1993

Radiosurgery requires integral procedure where special devices and computer systems are needed for localization, dose planning and treatment. The aim of this work is to verify the overall mechanical accuracy of our LINAC and develop dose calculation algorithm for LINAC radiosurgery. The alignment of treatment machine and the performance testing of the entire system were extensively carried out and the basic data such as percent depth dose, off-axis ratio and output factor were measured. A three dimensional treatment planning system for stereotactic radiosurgery has been developed. We used an IBM personal computer with C programming language (IBM personal system/2, Model 80386, IBM Co., USA) for calculating the dose distribution. As a result, deviations at isocenter on gantry and table rotation for our treatment machine were acceptable since they were less than 2 mm. According to the phantom experiments, the focusing isocenter were successful by the error of less than 2 mm. Finally, the mechanical accuracy of our three dimensional planning system was confirmed by film dosimetry in sphere phantom.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1769-1780
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• 2022

A new method of dose calculation algorithm, called GPU-accelerated Monte Carlo and collapsed cone Convolution (GMCC) was developed to improve the calculation speed of BNCT treatment planning system. The GPU-accelerated Monte Carlo routine in GMCC is used to simulate the neutron transport over whole energy range and the Collapsed Cone Convolution method is to calculate the gamma dose. Other dose components due to alpha particles and protons, are calculated using the calculated neutron flux and reaction data. The mathematical principle and the algorithm architecture are introduced. The accuracy and performance of the GMCC were verified by comparing with the FLUKA results. A water phantom and a head CT voxel model were simulated. The neutron flux and the absorbed dose obtained by the GMCC were consistent well with the FLUKA results. In the case of head CT voxel model, the mean absolute percentage error for the neutron flux and the absorbed dose were 3.98% and 3.91%, respectively. The calculation speed of the absorbed dose by the GMCC was 56 times faster than the FLUKA code. It was verified that the GMCC could be a good candidate tool instead of the Monte Carlo method in the BNCT dose calculations.

• Journal of Magnetics
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• v.21 no.2
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• pp.293-297
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• 2016

For mastectomy patients, sufficient doses of radiation should be delivered to the surface of the chest wall to prevent recurrence. A bolus is used to increase the surface dose on the chest wall, whereby the surface dose is confirmed with the use of a virtual bolus during the computerized treatment-planning process. The purpose of this study is an examination of the difference between the dose of the computerized treatment plan and the dose that is measured on the bolus. Part of the left breast of an Anderson Rando phantom was removed, followed by the attainment of computed tomography (CT) images that were used as the basis for computerized treatment plans that were established with no bolus, a 3 mm-thick bolus, a 5 mm-thick bolus, and a 10 mm-thick bolus. For the computerized treatment plan, a prescribed dose regimen was dispensed daily and planning target volume (PTV) coverage was applied according to the RTOG 1304 guidelines. Using each of the established computerized treatment plans, chest-wall doses of 5 points were measured; this chest-wall dose was used as the standard for the analysis of this study, while the level of significance was set at P < 0.05. The measurement of the chest-wall dose with no bolus is 1.6 % to 10.3 % higher, and the differences of the minimum average and the maximum average of the five measurement points are -13.8 and -1.9, respectively (P < 0.05); however, when the bolus was used, the dosage was measured as 3.7 % to 9.2 % lower, and the differences of the minimum average and the maximum average are 7.4 and 9.0, -1.2 and 17.4, and 8.1 and 19.8 for 3 mm, 5 mm, and 10 mm, respectively (P < 0.05). As the thickness of the bolus is increased, the differences of the average surface dose are further increased. There are a variety of factors that affect the surface dose on the chest wall during post-mastectomy radiation therapy, for which verification is required; in particular, a consideration of the appropriate thickness and the number of uses when a bolus is used, and which has the greatest effect on the surface dose on the chest wall, is considered necessary.

• The Journal of Korean Society for Radiation Therapy
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• v.2 no.1
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• pp.87-92
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• 1987

The authors have intended to measure intrinsic dose distribution by Farmer dosimeter in irregularly shaped fields such as L, M, T,-shape model in order to determine dose inhomogeneity in those models. We made 2 off-axis points in each model and measured the depth dose at 1.5,5, and 9cm below surface. The results showed $1-3\%$ dose discrepancy between 2 points. We also measured the depth dose by geometric approximation and computer calculation in those models, and came to the conclusion that computer calculation using Clarkson's principle is simpler and the measurements are to the ideal data obtained by the experiment in those three models of irregularly shaped fields than those of geometric approximation method.

• Radiation Oncology Journal
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• v.2 no.2
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• pp.281-285
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• 1984

The authors have intended to measure intrinsic dose distribution by Farmer dosimeter in irregularly shaped fields such as L.M and T shape models in order to determine dose inhomogeneity in those models. We made 2 off·axis points in each model and measured the depth dose at 1.5, 5 and 9cm below surface. The results showed $l\~3\%$ dose discrepancy between 2 points. We also measured the depth dose by geometric approximation and computer calculation in those models, and came to the conclusion that computer calculation using Clarkson's principle is simpler and the measurements are closer to the ideal data obtained by the experiment in three models of irregularly shaped fields than those of geometric approximation method.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.2
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• pp.33-41
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• 2019

Purpose: The purpose of this study is to improve the reduction of coverage of PTVs adjacent to organ at risk (OAR) by setting up overlapping Planning Target Volume (PTV) during Volumetric Modulated Arc Therapy(VMAT). Materials and Methods: In patients who received Whole Brain, Gall Bladder and Rectum radiation therapy, We compared the cover change, maximum dose, Homogenicity Index and Conformity Index of PTV and also compared the maximum dose and average dose change of Organ At Risk by organizing treatment plans that are not applied overlaped PTV and treatment plans that are applied overlaped PTV in areas where coverage is insufficient. Results: overage of treatment plans with overlapping PTVs was increased in all patients, and overall coverage was also increased in each of the four patients. The maximum dose for PTV was increased in five patients, and the Homogenicity Index and Conformity Index for all patients did not differ much. The maximum dose of the lens was increased by 1.12 times, and the maximum dose was decreased in two patients for brain stem. The mean dose of the eyeball was increased by a maximum of 1.15 times, and there was no significant difference between both parotid gland. In case of gallbladder cancer patients, the mean dose in the liver and colon was decreased, and the mean dose in the duodenum was increased. In the case of rectal cancer patients, the mean dose was reduced for both femur and bladder set as OARs. The overall MU was shown to be similar in four patients, excluding one. Conclusion: If the critical dose of OAR is considered and used properly, I think it is a useful way to improve coverage of PTV.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.298-299
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• 2002

WERC (Wakasa Wan Energy Research Center) has started the proton cancer therapy since June 2002. We use Hitachi 3D treatment planning (version 1.6) that can calculate the proton dose distribution by use of the pencil beam algorithm as well as the broad beam algorithm practically fast. This treatment planning software satisfies almost functions required in the proton therapy and includes some advanced techniques such as the 3D region glowing function that can search the target region three-dimensionally based on the CT-values. In this paper, we will introduce this planning system and present our evaluation from point of view of both clinical usage and QA.