• Radiation Oncology Journal
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• v.36 no.1
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• pp.11-16
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• 2018

Purpose: To investigate interobserver variation in target volume delineations for prostate cancer salvage radiotherapy using planning computed tomography (CT) versus combined planning CT and magnetic resonance imaging (MRI). Materials and Methods: Ten radiation oncologists independently delineated a target volume on the planning CT scans of five cases with different pathological status after radical prostatectomy. Two weeks later, this was repeated with the addition of planning MRI. The volumes obtained with CT only and combined CT and MRI were compared, and the effect of the addition of planning MRI on interobserver variability was assessed. Results: There were large differences in clinical target volume (CTV) delineated by each observer, regardless of the addition of planning MRI ($9.44-139.27cm^3$ in CT only and $7.77-122.83cm^3$ in CT plus MRI) and no significant differences in the mean and standard deviation of CTV. However, there were decreases in mean volume and standard deviation as a result of using the planning MRI. Conclusion: This study showed substantial interobserver variation in target volume delineation for salvage radiotherapy. The combination of planning MRI with CT tended to decrease the target volume and the variation.

• Progress in Medical Physics
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• v.24 no.4
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• pp.265-270
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• 2013

Correct target volume delineation is an important part of radiosurgery treatment planning process. We designed head phantom and performed target delineation to evaluate the volume differences due to radiosurgery treatment planning systems and image acquisition system, CT/MR. Delineated mean target volume from CT scan images was $2.23{\pm}0.08cm^3$ on BrainSCAN (NOVALS), $2.13{\pm}0.07cm^3$ on Leksell gamma plan (Gamma Knife) and $2.24{\pm}0.10cm^3$ on Multi plan (Cyber Knife). For MR images, $2.08{\pm}0.06cm^3$ on BrainSCAN, $1.94{\pm}0.05cm^3$ on Leksell gamma plan and $2.15{\pm}0.06cm^3$ on Multi plan. As a result, Differences of delineated mean target volume due to radiotherapy planning system was 3% to 6%. And overall mean target volume from CT scan images was 6.36% larger than those of MR scan images.

• Progress in Medical Physics
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• v.12 no.2
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• pp.171-175
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• 2001

We analyze the relation of dose volume histogram, conformity index and homogeneity index based on RTOG9005 for treatment planning result between framed based stereotactic radiosurgery(SRS) system and frameless SRS/T system to verify the difference of two systems in the intracranial target. There is same treatment planning result by two treatment planning systems.

• Progress in Medical Physics
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• v.35 no.1
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• pp.1-9
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• 2024

Margin inclusion or exclusion remains the most critical and controversial aspect of stereotactic radiosurgery (SRS) for metastatic brain tumors. This review aimed to examine the available literature on the impact of margins in SRS of brain metastasis and to assess the response of some medical physicists on the use of these margins. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses method was used to review articles published in PubMed, Embase, and Science Direct databases from January 2012 to December 2022 using the following keywords: planning target volume, brain metastasis, margin, and stereotactic radiosurgery. A simple survey consisting of five questions was completed by ten medical physicists with experience in SRS treatment planning. The results were analyzed using IBM SPSS Statistics version 26.0. Of the 1,445 articles identified, only 38 articles were chosen. Of these, eight papers were deemed relevant to the focus of this review. These papers showed an increase in the risk of radionecrosis, whereas differences in local control were variable as the margin increased. In the survey, the response rate to whether or not to use margins in SRS, a critical question, was 50%. Margin addition increases the risk of radio necrosis. The local control rate varies among treatment modalities and cannot be generalized. From the survey, no consensus was reached regarding the use of these margins. This calls for further deliberations among professionals directly involved in SRS.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.11
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• pp.4717-4721
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• 2014

Background: Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Materials and Methods: Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned. All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Results: Mean doses received by 100% and 90% of the target volume were $4.24{\pm}0.63$ and $4.9{\pm}0.56$ Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were $2.88{\pm}0.72$, $2.5{\pm}0.65$ and $2.2{\pm}0.57$ times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were $1.80{\pm}0.5$, $1.48{\pm}0.41$ and $1.35{\pm}0.37$ times higher than ICRU rectal reference point. Conclusions: Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.

• Radiation Oncology Journal
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• v.15 no.4
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• pp.387-392
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• 1997

Purpose : To quantify the movement of lung Parenchyma for ICRU 50 Planning Target Volume (PTV) delineation of the lung region. Materials and Method : Fluoroscopic observations and measurements are Performed on 10 patients with chest region cancer who have normal putmonary functions We have divided the lung region into 12 parts for the right lung, 10 parts for the left lung and four to five Points of lung parenchyma were selected for anatomical analysis Points, Fluoroscopic images are sent to a computer and then movements are measured. Results : Both lowe lobes showed the longest longitudinal movements because of breathing (average 14.1mm, maximum 22.1mm), while anteroposterior displacement showed the smallest value. Lateral movements of the lung parenchyma averaged 6.6mm, and the maximum value was 9.1mm, (both hilar regions showed maximum values because of cardiac motion) Conclusion : We could quantify the lung movements by measuring parenchyma displacements. The movements of both upper lobes were less than those of the middle and upper lobes in longitudinal and transverse movements. Optimal margins can be selected for PTV delineation using these results.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7401-7405
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• 2014

Background: Postoperative chemoradiotherapy is accepted as standard treatment for stage IB-IV, M0 gastric cancer. Radiotherapy (RT) planning of gastric cancer is important because of the low radiation tolerance of surrounding critical organs. The purpose of this study was to compare the dosimetric aspects of 2-dimensional (2D) and 3-dimensional (3D) treatment plans, with the twin aims of evaluating the adequacy of 2D planning fields on coverage of planning target volume (PTV) and 3D conformal plans for both covering PTV and reducing the normal tissue doses. Materials and Methods: Thirty-six patients with stage II-IV gastric adenocarcinoma were treated with adjuvant chemoradiotherapy using 3DRT. For each patient, a second 2D treatment plan was generated. The two techniques were compared for target volume coverage and dose to normal tissues using dose volume histogram (DVH) analysis. Results: 3DRT provides more adequate coverage of the target volume. Comparative DVHs for the left kidney and spinal cord demonstrate lower radiation doses with the 3D technique. Conclusions: 3DRT produced better dose distributions and reduced radiation doses to left kidney and spinal cord compared to the 2D technique. For this reason it can be predicted that 3DRT will result in better tumor control and less normal tissue complications.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3816-3823
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• 2022

This work analyzed the dosimetric difference between the intensity modulated radiotherapy (IMRT), partial/single/double-arc volumetric modulated arc therapy (PA/SA/DA-VMAT) techniques in treatment planning for treating more than one target of lung cancer at different isocenters. IMRT and VMAT plans at different isocenters were created systematically using a Harold heterogeneous lung phantom. The conformity index (CI), homogeneity index (HI), gradient index (GI), dose-volume histogram and mean and maximum dose of the PTV were calculated and analyzed. Furthermore, the dose-volume histogram and mean and maximum doses of the OARs such as right lung, contralateral lung and non GTV were determined from the plans. The IMRT plans showed the superior target dose coverage, higher mean and maximum values than other VMAT techniques. PA-VMAT technique shows more lung sparing and DA-VMAT increases the V_5/10/20 values of contralateral lung than other VMAT and IMRT techniques. The IMRT technique achieves highly conformal dose distribution to the target than other VMAT techniques. Comparing to the IMRT plans, the higher V_5/10/20 and mean lung dose were observed in the contralateral lung in the DA-VMAT.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.2
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• pp.77-90
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• 2009

Total profit level Increases if a company increase the cost for achieving R&D related goals of equipment productivity enhancement, production cost saving, or for achieving equipment scale target, sales volume goal. But how much money should be invested to achieve a certain level of profit? We formulated the model to set the optimal goal levels to minimize the investment cost under the constraint that certain level of total profit should be guaranteed. This model derived from a case of P steel company. We found that this should be considered in relation with the production sales planning (known as optimal product mix problem) to guarantee the profit. We suggested a nonlinear programming model, 3 valiant form of the p+roduct mix problem. We can find the optimal Investment level for the R&D related goals or sales volume goal, equipment scale target for the P steel company using the model.

• Radiation Oncology Journal
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• v.28 no.3
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• pp.177-183
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• 2010

Purpose: Simulation using computed tomography (CT) is now widely available for radiation treatment planning for breast cancer. It is an important tool to help define the tumor target and normal tissue based on anatomical features of an individual patient. In Korea, most patients have small sized breasts and the purpose of this study was to review the margin of treatment field between conventional two-dimensional (2D) planning and CT based three-dimensional (3D) planning in patients with small breasts. Materials and Methods: Twenty-five consecutive patients with early breast cancer undergoing breast conservation therapy were selected. All patients underwent 3D CT based planning with a conventional breast tangential field design. In 2D planning, the treatment field margins were determined by palpation of the breast parenchyma (In general, the superior: base of the clavicle, medial: midline, lateral: mid - axillary line, and inferior margin: 2 m below the inframammary fold). In 3D planning, the clinical target volume (CTV) ought to comprise all glandular breast tissue, and the PTV was obtained by adding a 3D margin of 1 cm around the CTV except in the skin direction. The difference in the treatment field margin and equivalent field size between 2D and 3D planning were evaluated. The association between radiation field margins and factors such as body mass index, menopause status, and bra size was determined. Lung volume and heart volume were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. Results: The margins of the treatment field were smaller in the 3D planning except for two patients. The superior margin was especially variable (average, 2.5 cm; range, -2.5 to 4.5 cm; SD, 1.85). The margin of these targets did not vary equally across BMI class, menopause status, or bra size. The average irradiated lung volume was significantly lower for 3D planning. The average irradiated heart volume did not decrease significantly. Conclusion: The use of 3D CT based planning reduced the radiation field in early breast cancer patients with small breasts in relation to conventional planning. Though a coherent definition of the breast is needed, CT-based planning generated the better plan in terms of reducing the irradiation volume of normal tissue. Moreover it was possible that 3D CT based planning showed better CTV coverage including postoperative change.