• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.57-68
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• 2017

Purpose: The purpose of this study was to compare volumetric modulated arc therapy(VMAT) with fixed-field intensity modulated radiation therapy(IMRT) using non-coplanar beam when the shape of target is irregular and the location is adjacent to organ at risk(OAR). Materials and Methods: The subjects of this study were a total of 6 patients who had radiation therapy for whole scalp(2 patients), partial scalp(2 patients), and whole ventricle(2 patients) by True Beam STX(Varian Medical Systems, USA). VMAT plans consisted of coplanar or non-coplanar arcs which can minimize the volume of OAR included in beamlets. All fixed-field IMRT plans consisted of non-coplanar beams using more than 2 angles of Couch. Results: The VMAT and IMRT plans were compared with regard to the maximum dose of both lens, both optic nerves, optic chiasm, and brain stem and the mean dose of both eyeballs and hippocampus. VMAT plans showed higher dose than ncIMRT plans at more than 6 of all OARs in every patient, and the ratio was from 1.1 times to 8.2 times. In case of total scalp and partial scalp, the volume of brain which received more than 20 Gy in the VMAT plans was 2 times larger than the volume in the ncIMRT plans. In case of whole ventricle, there was no significant difference. Target coverage was satisfied in both plans($PTV_{100%}=95%$). The maximum dose in target volume and required monitor unit(MU) of ncIMRT were higher than them of VMAT plans. Conclusion: Even though ncIMRT is less efficient than VMAT with regard to required MU and treatment time, the dose to OARs is much lower than VMAT and PTV Coverage is similar with VMAT. If the shape of target is irregular and location is adjacent to OAR, comparison VMAT plan with ncIMRT plan deserves to be considered.

• Journal of The Korean Radiological Technologist Association
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• v.25 no.1
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• pp.63.2-64
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• 1999

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.115-119
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• 1999

• Radiation Oncology Journal
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• v.38 no.2
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• pp.138-147
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• 2020

Purpose: To evaluate the dosimetric variations in patients of head and neck cancer treated with definitive or adjuvant radiotherapy using optimized non-coplanar (ncVMAT) beams with coplanar (cVMAT) beams using volumetric arc therapy. Materials and Methods: Twenty-two patients of head and neck cancer that had received radiotherapy using VMAT in our department were retrospectively analyzed. Each of the patients was planned using coplanar and non-coplanar orientations using an optimized couch angle and fluences. We analyzed the Conformity Index (C_IRTOG), Dose Homogeneity Index (DHI), Heterogeneity Index (HI_RTOG), low dose volume, target and organs-at-risk coverage in both the plans without changing planning optimization parameters. Results: The prescription dose ranged from 60 Gy to 70 Gy. Using ncVMAT, C_IRTOG, DHI and HI_RTOG, and tumor coverage (ID_95%) had improved, low dose spillage volume in the body V_5Gy was increased and V_10Gy was reduced. Integral dose and intensity-modulated radiation therapy factor had increased in ncVMAT. In the case of non-coplanar beam arrangements, maximum dose (D_max) of right and left humeral head were reduced significantly whereas apex of the right and left lung mean dose were increased. Conclusion: The use of ncVMAT produced better target coverage and sparing of the shoulder and soft tissue of the neck as well as the critical organ compared with the cVMAT in patients of head and neck malignancy.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.1
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• pp.31-39
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• 2011

Purpose: Helical Tomotherapy allows only coplanar beam delivery because it does not allow couch rotation. We investigated a method to introduce non-coplanar beam by tilting a patient's head for Tomotherapy. The aim of this study was to compare intrafractional movement during Tomotherapy between coplanar and non-coplanar patient's setup. Materials and Methods: Helical Tomotherapy was used for treating eight patients with intracranial tumor. The subjects were divided into three groups: one group (coplanar) of 2 patients who lay on S-plate with supine position and wore thermoplastic mask for immobilizing the head, second group (non-coplanar) of 3 patients who lay on S-plate with supine position and whose head was tilted with Variable Axis Baseplate and wore thermoplastic mask, and third group (non-coplanar plus mouthpiece) of 3 patients whose head was tilted and wore a mouthpiece immobilization device and thermoplastic mask. The patients were treated with Tomotherapy after treatment planning with Tomotherapy Planning System. Megavoltage computed tomography (MVCT) was performed before and after treatment, and the intrafractional error was measured with lateral(X), longitudinal(Y), vertical(Z) direction movements and vector ($\sqrt{x^2+y^2+z^2}$) value for assessing overall movement. Results: Intrafractional error was compared among three groups by taking the error of MVCT taken after the treatment. As the correction values (X, Y, Z) between MVCT image taken after treatment and CT-simulation image are close to zero, the patient movement is small. When the mean values of movement of each direction for non-coplanar setup were compared with coplanar setup group, X-axis movement was decreased by 13%, but Y-axis and Z-axis movement were increased by 109% and 88%, respectively. Movements of Y-axis and Z-axis with non-coplanar setup were relatively greater than that of X-axis since a tilted head tended to slip down. The mean of X-axis movement of the group who used a mouthpiece was greater by 9.4% than the group who did not use, but the mean of Y-axis movement was lower by at least 64%, and the mean of Z-axis was lower by at least 67%, and the mean of Z-axis was lower by at least 67%, and the vector was lower by at least 59% with the use of a mouthpiece. Among these 8 patients, one patient whose tumor was located on left frontal lobe and left basal ganglia received reduced radiation dose of 38% in right eye, 23% in left eye, 30% in optic chiasm, 27% in brain stem, and 8% in normal brain with non-coplanar method. Conclusion: Tomotherapy only allows coplanar delivery of IMRT treatment. To complement this shortcoming, Tomotherapy can be used with non-coplanar method by artificially tilting the patient's head and using an oral immobilization instrument to minimize the movement of patient, when intracranial tumor locates near critical organs or has to be treated with high dose radiation.

• Progress in Medical Physics
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• v.2 no.2
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• pp.121-128
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• 1991

Radiosurgery treatment in the brain requires detailed information on three-dimensional dose distribution. A three-dimensional treatment planning is a prerequisite for treatment plan optimization. It must cover 3-D methods for representing the patient, the dose distributions, and beam settings. Three-dimensional dose models for non-coplanar moving arcs were developed using measured single beam data and efficient 3-D dose algorithms for circular fields. The implementation of three dimensional dose algorithms with stereotactic radiosurgery and the application of the algorithms to several cases are discussed.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.117-125
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• 2021

Purpose: To purpose of this study is to find the correlation of the Set-up error according to the couch rotation and suggest additional margin setting for the GTV. Target and Method: Each scenario treatment plan was created by making the frequency of non-coplanar beams different among all beams. The set-up error value was measured by using the Exact System and the dose accuracy was evaluated by creating a re-treatment plan. Results: When the couch was rotated by 30°, 45°, 60°, and 90°, the mean of the X-axis values was measured to be 0.29 mm, 0.26 mm, 0.51 mm, and 0.08 mm, respectively. The mean of the Y-axis values was measured to be 0.75 mm, 0.5mm, 0.35 mm, and 0.29 mm, respectively. The mean of the Z-axis values was measured to be 0.5 mm, 0.28 mm, 0.22 mm, and 0.1 mm, respectively. There were dose reductions of 0.1%, 3.1%, 1.9% in D99 for 1-NC VMAT, 2-NC VMAT, and 3-NC VMAT, respectively. Conclusion: When treating with 50% or more of non-coplanar beams among total beams, image verification is required. And it is considered to make the treatment plan by adding a 1.5 mm margin to the GTV.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.2
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• pp.115-122
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• 2015

Purpose : The aim of this study, evaluate the accuracy of HeaxPOD evo RT system using the non-coplanar beam. Materials and Methods : 13 treatment plans are used which applied non-coplanar beams and 10 treatment plans which coplanar beams are used. the correction value what adjust to 6D couch is determined by each patient's setup errors only rotation direction. The study executed followings. first, Applying the correction value, measure the point dose and calculate the ${\gamma}$-index(${\gamma}=3%$ / 3 mm, ${\gamma}=2%$ / 2 mm). second, acquire data as previous methods without correction by HexaPOD. Results : For comparing the two results, we find out the more precise applying HexaPOD by point dose 0.2% in coplanar and non-coplanar. in the case of ${\gamma}$-index<1(${\gamma}=3%$ / 3 mm), more precise 2.2% in coplanar and 7% in Non-coplanar. Particularly, ${\gamma}$-index<1(2% / 2 mm) show the difference 9.2% in coplanar and 15.1% non-coplanar between apply HexaPOD and dose not apply HexaPOD. Conclusion : Using the HexaPOD is more precise than without HexaPOD. It suggests that HexaPOD evo RT system is very useful for precise and high dose delivery.

• Journal of radiological science and technology
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• v.47 no.4
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• pp.271-278
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• 2024

This study aimed to evaluate the impact of changes in beam arrangement and arc counts on dosimetric factors in volumetric modulated arc therapy (VMAT) inverse radiation therapy planning for hippocampal-avoidance whole brain radiation therapy (HA-WBRT) by using the Elekta Monaco radiation therapy planning system (RTPs). For coplanar VMAT, both the arc per beam (APB) method and the beam determined arc(BDA) method, which is determined by the number of beams, were applied. For non-coplanar VMAT, the BDA method was utilized, and a total of 9 treatment plans were established by varying the arc counts. All radiation therapy plans met the radiation oncology group (RTOG) 0933 protocol standards, and 14 dosimetric factors were compared and analyzed. The results showed that the BDA-NC VMAT method demonstrated superior performance in terms of planning target volume (PTV) coverage and protection of normal organs, while APB-VMAT was advantageous in terms of hippocampal protection, monitor unit and delivery time. This study is expected to contribute to the efficient establishment of HA-WBRT plans considering the changes in beam arrangement and rotation arc numbers in Monaco RTPs.

• Journal of Yeungnam Medical Science
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• v.36 no.1
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• pp.36-42
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• 2019

Background: The purpose of this study was to evaluate the efficacy and feasibility of non- coplanar whole brain radiotherapy (NC-WBRT) for parotid sparing. Methods: Fifteen cases, previously treated with WBRT were selected. NC-WBRT plans were generated. The beam arrangement for the non-coplanar plans consisted of superior anterior, right, and left beams. After generation of the non-coplanar plans a field-in-field technique was applied to the bilateral parallel opposed beams in order to reduce maximum dose and increase dose homogeneity. The NC-WBRT plans were subsequently compared with the previously generated bilateral WBRT (B-WBRT) plans. A field-in-field technique was also used with the B-WBRT plans according to our departmental protocol. As per our institutional practice a total dose of 30 Gy in 10 fractions of WBRT was administered 5 days a week. Results: The mean dose to the parotid gland for the two different plans were 16.2 Gy with B-WBRT and 13.7 Gy with NC-WBRT (p<0.05). In the NC-WBRT plan, the V5Gy, V10Gy, V15Gy, V20Gy, and V25Gy of the parotid were significantly lower (p<0.05) than those of the B-WBRT plan. The $D_{max}$ of the lens was also lower by 10% with NC-WBRT. Conclusion: The use of NC-WBRT plans could be a simple and effective method to reduce irradiated volumes and improve the dose-volume parameters of the parotid gland.