• Progress in Medical Physics
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• v.24 no.3
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• pp.154-161
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• 2013

This study assessed compared photon and proton treatment techniques, such as intensity modulated radiation therapy (IMRT), uniform scanning proton therapy (USPT), and intensity modulated proton therapy (IMPT), for a total of 10 prostate cancers. All treatment plans delivered 70 Gy to 95% of the planned target volume in 28 fractions. IMRT plans had 7 fields for the step and shoot technique, while USPT and IMPT plans employed two equally weighted, parallel-opposed lateral fields to deliver the prescribed dose to the planned target. Inverse planning was then incorporated to optimize IMPT. The homogeneity index (HI) and conformity index (CI) for the target and the normal tissue complication probability (NTCP) for organ at risk (OAR) were calculated. Although the mean HI and CI for target were not significantly different for each treatment techniques, the NTCP of the rectum was 2.233, 3.326, and 1.707 for IMRT, USPT, and IMPT, respectively. The NTCP of the bladder was 0.008, 0.003, and 0.002 respectively. The NTCP values at the rectum and bladder were significantly lower using IMPT. Our study shows that using proton therapy, particularly IMPT, to treat prostate cancer could be beneficial compared to 7-field IMRT with similar target coverage. Given these results, radiotherapy using protons, particularly optimized IMPT, is a worthwhile treatment option for prostate cancer.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.63-63
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• 2003

Purpose: Planning target volume (PTV) for tumors in abdomen or thorax includes enough margin for breathing-related movement of tumor volumes during treatment. We developed a simple and handy method, which can reduce PTV margins in patients with moving tumors, respiratory motion reduction device system (RMRDs). Materials and Methods: The patients clinical database was structured for moving tumor patients and patient setup error measurement and immobilization device effects were investigated. The system is composed of the respiratory motion reduction device utilized in prone position and abdominal presser (strip device) utilized in the supine position, moving phantom and the analysis program, which enables the analysis on patients setup reproducibility. It was tested for analyzing the diaphragm movement and CT volume differences from patients with RMRDs, the magnitude of PTV margin was determined and dose volume histogram (DVH) was computed using a treatment planning software. Dose to normal tissue between patients with RMRDs and without RMRDs was analyzed by comparing the fraction of the normal liver receiving to 50% of the isocenter dose(TD50). Results: In case of utilizing RMRDs, which was personally developed in our hospital, the value was reduced to $5pm1.4 mm$, and in case of which the belt immobilization device was utilized, the value was reduced to 3$pm$0.9 mm. Also in case of which the strip device was utilized, the value was proven to reduce to $4pm.3 mm$0. As a result of analyzing the TD50 is irradiated in DVH according to the radiation treatment planning, the usage of the respiratory motion reduction device can create the reduce of 30% to the maximum. Also by obtaining the digital image, the function of comparison between the standard image, automated external contour subtraction, and etc were utilized to develop patients setup reproducibility analysis program that can evaluate the change in the patients setup. Conclusion: Internal organ motion due to breathing can be reduced using RMRDs, which is simple and easy to use in clinical setting. It can reduce the organ motion-related PTV margin, thereby decrease volume of the irradiated normal tissue.

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.124-125
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• 2010

• Journal of Radiation Protection and Research
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• v.37 no.3
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• pp.146-148
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• 2012

The use of GEANT4 simulation toolkit has increased in the radiation medical field for the design of treatment system and the calibration or validation of treatment plans. Moreover, it is used especially on calculating dose simulation using medical data for radiation therapy. However, using internal visualization tool of GEANT4 detector constructions on expressing dose result has deficiencies because it cannot display isodose line. No one has attempted to use this code to a real patient's data. Therefore, to complement this problem, using the result of gMocren that is a three-dimensional volume-visualizing tool, we tried to display a simulated dose distribution and isodose line on medical image. In addition, we have compared cross-validation on the result of gMocren and GEANT4 simulation with commercial radiation treatment planning system. We have extracted the analyzed data of dose distribution, using real patient's medical image data with a program based on Monte Carlo simulation and visualization tool for radiation isodose mapping.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.162-163
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• 1999

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.181-186
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• 2013

Purpose: This study executed therapy plans on prostate cancer (homogeneous density area) and lung cancer (non-homogeneous density area) using radiation treatment planning systems such as $Pinnacle^3$ (version 9.2, Philips Medical Systems, USA) and Eclipse (version 10.0, Varian Medical Systems, USA) in order to quantify the difference between dose calculation according to density in IMRT. Materials and Methods: The subjects were prostate cancer patients (n=5) and lung cancer patients (n=5) who had therapies in our hospital. Identical constraints and optimization process according to the Protocol were administered on the subjects. For the therapy plan of prostate cancer patients, 10 MV and 7Beam were used and 2.5 Gy was prescribed in 28 fx to make 70 Gy in total. For lung cancer patients, 6 MV and 6Beam were used and 2 Gy was prescribed in 33 fx to make 66 Gy in total. Through two therapy planning systems, maximum dose, average dose, and minimum dose of OAR (Organ at Risk) of CTV, PTV and around tumor were investigated. Results: In prostate cancer, both therapy planning systems showed within 2% change of dose of CTV and PTV and normal organs (Bladder, Both femur and Rectum out) near the tumor satisfied the dose constraints. In lung cancer, CTV and PTV showed less than 2% changes in dose and normal organs (Esophagus, Spinal cord and Both lungs) satisfied dose restrictions. However, the minimum dose of Eclipse therapy plan was 1.9% higher in CTV and 3.5% higher in PTV, and in case of both lungs there was 3.0% difference at V5 Gy. Conclusion: Each TPS according to the density satisfied dose limits of our hospital proving the clinical accuracy. It is considered more accurate and precise therapy plan can be made if studies on treatment planning for diverse parts and the application of such TPS are made.

• Journal of Korean Neurosurgical Society
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• v.42 no.3
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• pp.159-167
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• 2007

Vestibular schwannoma (VS) is a benign tumor typically originated in the schwann cell of vestibular nerve and usually accompany hearing symptom. Microsurgical removal and radiosurgery have a great role for the treatment of VS. Recently radiosurgery has been considered as an alternative or primary treatment for VS with the tremendous increase of patients who were treated with gamma knife radiosurgery (GKS) though microsurgery still takes the premier. By many published results, it is proved that GKS is a effective and noninvasive technique for VS, especially small sized tumors with satisfactory tumor control rate. The authors assumed that GKS can be expected to achieve satisfactory tumor control rate for small VS under 5cc in volume. A major interest regarding radiosurgery nowadays is to determine the optimal radiation dose for hearing preservation to improve the quality of life of patients. The more high radiation dose are used for effective tumor growth control, the more radiation-related complications like as hearing deficit, the impairment of other cranial nerve function are increased. Since 1990's the mean radiation dose for tumor margin was more than 18 Gy, but there were high complication rate in spite of good tumor growth control. After the year of 2000, under the influence of advanced neuro-imaging techniques and radiosurgical planning system which enable clinicians to do more precise planning, marginal dose for VS has been decreased to 12-13 Gy and the radiation-related complications has been reduced. But because there may be a unexpected radiation induced complications as time goes by after the latency period, optimal radiation dose for VS should be established on the basis of more long term follow-up observation.

• Progress in Medical Physics
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• v.34 no.2
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• pp.15-22
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• 2023

This study compared the dose calculated using the electron Monte Carlo (eMC) dose calculation algorithm employing the old version (eMC V13.7) of the Varian Eclipse treatment-planning system (TPS) and its newer version (eMC V16.1). The eMC V16.1 was configured using the same beam data as the eMC V13.7. Beam data measured using the VitalBeam linear accelerator were implemented. A box-shaped water phantom (30×30×30 cm³) was generated in the TPS. Consequently, the TPS with eMC V13.7 and eMC V16.1 calculated the dose to the water phantom delivered by electron beams of various energies with a field size of 10×10 cm². The calculations were repeated while changing the dose-smoothing levels and normalization method. Subsequently, the percentage depth dose and lateral profile of the dose distributions acquired by eMC V13.7 and eMC V16.1 were analyzed. In addition, the dose-volume histogram (DVH) differences between the two versions for the heterogeneous phantom with bone and lung inserted were compared. The doses calculated using eMC V16.1 were similar to those calculated using eMC V13.7 for the homogenous phantoms. However, a DVH difference was observed in the heterogeneous phantom, particularly in the bone material. The dose distribution calculated using eMC V16.1 was comparable to that of eMC V13.7 in the case of homogenous phantoms. The version changes resulted in a different DVH for the heterogeneous phantoms. However, further investigations to assess the DVH differences in patients and experimental validations for eMC V16.1, particularly for heterogeneous geometry, are required.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.71-78
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• 2021

Purpose: To evaluate the inter-fractional position and respiratory reproducibility of lung and liver tumors using pressure conserving type(P-type) abdominal compressor in volumetric modulated arc therapy(VMAT). Materials and methods: Six lung cancer patients and three liver cancer patients who underwent VMAT using a P-type abdominal compressor were included in this study. Cone-beam computed tomography(CBCT) images were acquired before each treatment and compared with planning CT images to evaluate the inter-fractional position reproducibility. The position variation was defined as the difference of position shift values between target matching and bone matching. 4-dimensional cone-beam computed tomography(4D CBCT) images were acquired weekly before treatment and compared with planning 4DCT images to evaluate the inter-fractional respiratory reproducibility. The respiratory variation was calculated by the magnitude of excursions by breathing. Results: The mean ± standard deviation(SD) of overall position variation values, 3D vector in the three translational directions were 1.1 ± 1.4 mm and 4.5 ± 2.8 mm for the lung and liver, respectively. The mean ± SD of respiratory variation values were 0.7 ± 3.4 mm (p = 0.195) in the lung and 3.6 ± 2.6 mm (p < 0.05) in the liver. Conclusion: The use of P-type compressor in lung and liver VMAT was effective for stable control of inter-fractional position and respiratory variation by reproduction of abdominal compression. Appropriate PTV margin must be considered in treatment planning, and image guidance before each treatment are required in order to obtain more stable reproducibility

• Progress in Medical Physics
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• v.27 no.4
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• pp.267-271
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• 2016

In this study, we present the commissioning and validation results of a dedicated scanning nozzle. The dedicated scanning nozzle is installed in one of the two gantry treatment rooms at Samsung Proton Therapy Center. Following a successful completion of the acceptance test, the commissioning process including the beam data measurement for treatment planning system has been conducted. Extended measurements have been conducted as a validation of the clinical performance of the nozzle and various quality assurance protocols have been prepared.