• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.73-77
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• 2004

Purpose of the radio-therapy is maximize the radiation dose to the tumor while minimizing the dose to the critical organ. Carcinoma of the uterine cervix treatment are external irradiation or an interstitial brachtheraphy make use of isotope. Brachytherapy is a method of radiotherapy in advantage to achieve better local control with minimum radiation toxicity in comparison with external irradiation because radiation dose is distributed according to the inverse square low of gamma-ray emitted from the implanted sources. Authors make use of the patients data which 192Ir gives medical treatment intrcavity. Intracavitary radiation of the uterine cervix cancer, critical organ take $20\%$ below than exposure dose of A point in the ICRU report. None the less of the advice, Radiation proctitis and radiation cystitis are frequent and problematic early complications in patients treated with radiation for the uterine cervix cancer. In brachytherapy of uterine cervical cancer using a high dose rate remote afterloading system, it is of prime importance to deliver a accurate dose in each fractionated treatment by minimizing the difference between the pre-treatment planned and post-treatment calculated doses. Use of packing to reduce late complications intracavitary radiation of the uterine cervix cancer. Bladder and rectum changes exposure dose rate by radiotherphy make use of packing.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.35-40
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• 2018

Purpose : The range of force differs from the size of proton energy used in our hospital. The compensator enables to change energy size based on distal thickness which also makes changes in dose rate. Therefore, the purpose of this study is to evaluate the effect of changing the thickness of compensator distal on dose range and beam on time. Subject and Methodology : Five low energy patients who have received proton therapy were selected as subjects for this study. Beam on was checked for the selected patients during the existing therapy. After then, the thickness of distal of compensator was increased by 2 cm up to 14 cm through proton therapy plan system(TPS) for comparative analysis. For the evaluation of dose range, the value of the target's conformity index(CI) and the maximum dose of rear side target's organ at risk(OAR) were compared. Furthermore, to evaluate the effect of therapy time, beam on time was compared by making compensator distal in each thickness. Result : The result of homogeneity index and conformity index of the increased compensator distal showed the same level in all patients. The comparison results of OAR of target rear side showed 7 cGy at spine cord of abdomen at maximum, 88 cGy at eyeball's RT lens, 391 cGy at RT lens of nasal cavity 51 cGy at trachea of the mediastinum, and 661 cGy at a small bowl of the pelvis. The comparison results of the beam on time showed a reduction from 126 seconds to 62 seconds for the abdomen, from 105 seconds to 37 seconds for the eyeball, from 187 seconds to 134 seconds for nasal cavity, from 100 seconds to 40 seconds for mediastinum, from 440 seconds to 118 seconds for the pelvis. Conclusion : The research result showed that as the distal thickness of compensator increased, the size of energy increased. In addition, beam on decreased due to the increase of dose rate. It is expected that the result would help reduce the treatment time and increase the convenience of patients if it is applied to liver patients who need respiratorygated therapy and pediatric patients. However, distal penumbra increased as the size energy increased. Therefore, in treating cases where OAR is in the vicinity of the target rear side, the influence of penumbra should be taken into account in adjusting thickness level of the compensator in proton therapy plan.

• Progress in Medical Physics
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• v.23 no.3
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• pp.162-168
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• 2012

In proton therapy, in vivo dose verification is one of the most important parts to fully utilize characteristics of proton dose distribution concentrating high dose with steep gradient and guarantee the patient safety. Currently, in order to image the proton dose distribution, a prompt gamma distribution detection system, which consists of an array of multiple CsI(Tl) scintillation detectors in the vertical direction, a collimator, and a multi-channel DAQ system is under development. In the present study, the optimal design of prompt gamma distribution detection system was studied by Monte Carlo simulations using the MCNPX code. For effective measurement of high-energy prompt gammas with enough imaging resolution, the dimensions of the CsI(Tl) scintillator was determined to be $6{\times}6{\times}50mm^3$. In order to maximize the detection efficiency for prompt gammas while minimizing the contribution of background gammas generated by neutron captures, the hole size and the length of the collimator were optimized as $6{\times}6mm^2$ and 150 mm, respectively. Finally, the performance of the detection system optimized in the present study was predicted by Monte Carlo simulations for a 150 MeV proton beam. Our result shows that the detection system in the optimal dimensions can effectively measure the 2D prompt gamma distribution and determine the beam range within 1 mm errors for 150 MeV proton beam.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.771-779
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• 2021

It is necessary to overlap several peaks to form spread out Bragg peak (SOBP) in order to cover the tumor volume because a mono-energetic proton beam forms a narrow Bragg peak. The tumor density has been considered as a brain tissue and then the absorbed dose of the tumor is calculated using Monte Carlo simulations. However, densities of tumors were not a constant. In this study, the SOBP of proton beams was calculated according to changing density of tumors by using Geant4. Tumors were selected as 10 mm and 20 mm width which were the treatment range in the brain phantom. The energies and relative weights of the proton beams were calculated using mathematical formula to form the SOBP suitable for the location and size of the tumor. As the density of the tumor was increased, the 95% modulation range and the practical range were decreased, and average absorbed dose in the 95% modulation range was increased. The change of the tumor density affects the dose distribution of the proton beams, which results in short SOBP within the tumor volume. The consideration of the tumor density affects the determination of the range, so that the margin of the treatment volume can be minimized, and the advantages of proton therapy can be maximized.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.28 no.1
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• pp.32-37
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• 2017

Background and Objectives : This study evaluated the efficacy of combination therapy of proton pump inhibitor (PPI) and steroid inhaler (SI), with or without botulinum toxin injection (BTX) for contact granuloma. Subjects and Methods : Fourteen contact granuloma patients were enrolled in this study. Combination therapy of PPI and SI were used for the first line treatment. When combination therapy was not effective, BTX was performed as the second method. Treatment results were recorded as responsible or non-responsible. Farwell grade, size, history of voice abuse, gender, and reflux finding score (RFS) were compared between responsible group and non-responsible group. Results : Initial response rate was 28.6% after treatment of PPI and SI. BTX was performed on three un-responsible patients. After BTX injection, three patients had complete remission of granuloma. Final response rate was 50.0%. Un-responsible group had significantly higher RFS than responsible group. Conclusion : The efficacy of PPI and SI was limited for contact granuloma in this study. Botulium toxin injection was recommended in early phase when PPI and SI did not effective for contact granuloma. Prospective studies evaluating the effects of PPI and SI are warranted.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.192-194
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• 2002

We present the results on the calibration of iso-center positions using the quality assurance system established at PMRC for determination of center position in X-ray and proton irradiation fields. Details on the system are presented in another presentation in this session. The equipment in the system is mounted on a patient treatment bed in each proton exposure room, G1 or G2. A center of a stainless ball on the equipment is set at a cross of laser markers located around the iso-center and fixed on the room and on the snout in the gantry. A proton beam or an X-ray beam is exposed onto the ball through a brass collimator of 100 mm ${\times}$ 100 mm and projected onto the imaging plate set at I cm behind the ball. On the axis perpendicular to the thrust axis of the gantry on the imaging plate, a distance between a center of the collimator image and a center of the ball image varies as a cosine function of gantry angles unless the ball is set on the iso-center. An amplitude of the cosine curve shows the distance between the ball and the iso-center, an offset the offset of the collimator, and a phase shift at a zero crossing point the ball direction viewed from the iso-center. We present the relation among the iso-center position, the laser maker position, and the center of proton and X-ray irradiation fields. Its stability and its reproducibility are discussed.

• Progress in Medical Physics
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• v.30 no.1
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• pp.14-21
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• 2019

Purpose: To report the initial experience of patient-specific quality assurance (pQA) for the wobbling and line-scanning proton therapy at Samsung Medical Center. Materials and Methods: The pQA results of 89 wobbling treatments with 227 fields and 44 line-scanning treatments with 118 fields were analyzed from December 2015 to June 2016. For the wobbling method, proton range and spread-out Bragg peak (SOBP) width were verified. For the line-scanning method, output and two-dimensional dose distribution at multiple depths were verified by gamma analysis with 3%/3 mm criterion. Results: The average range difference was -0.44 mm with a standard deviation (SD) of 1.64 mm and 0.1 mm with an SD of 0.53 mm for the small and middle wobbling radii, respectively. For the line-scanning method, the output difference was within ${\pm}3%$. The gamma passing rates were over 95% with 3%/3 mm criterion for all depths. Conclusions: For the wobbling method, proton range and SOBP width were within the tolerance levels. For the line-scanning method, the output and two-dimensional dose distribution showed excellent agreement with the treatment plans.

• Economic and Environmental Geology
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• v.48 no.3
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• pp.241-246
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• 2015

Helicobacter pylori is an important transmissible human pathogen found on the luminal surface of the gastric epithelium. The organism can persist in the stomach indefinitely and causes gastroduodenal inflammation that may proceed to atrophic gastritis, peptic ulcer, gastric MALT lymphoma, and gastric cancer. Standard triple therapy which consists of proton pump inhibitor (PPI) plus two antibiotics (amoxicillin and clarithromycin) is now generally used in Korea, however, eradication rates of H. pylori has been decreasing due to increasing antibiotic resistance. In this review, current second-line treatment regimens, difficult problems on treatment, necessity of local target therapy, applicability of clay minerals as a drug delivery system (DDS), and a new therapeutic strategy and its study plans will be discussed.

• Progress in Medical Physics
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• v.32 no.2
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• pp.25-39
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• 2021

Brachytherapy, along with external beam radiation therapy (EBRT), is an essential and effective radiation treatment process. In brachytherapy, in contrast to EBRT, the radiation source is radioisotopes. Because these isotopes can be positioned inside or near the tumor, it is possible to protect other organs around the tumor while delivering an extremely high-dose of treatment to the tumor. Brachytherapy has a long history of more than 100 years. In the early 1900s, the radioisotopes used for brachytherapy were only radium or radon isotopes extracted from nature. Over time, however, various radioisotopes have been artificially produced. As radioisotopes have high radioactivity and miniature size, the application of brachytherapy has expanded to high-dose-rate brachytherapy. Recently, advanced treatment techniques used in EBRT, such as image guidance and intensity modulation techniques, have been applied to brachytherapy. Three-dimensional images, such as ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography are used for accurate delineation of treatment targets and normal organs. Intensity-modulated brachytherapy is anticipated to be performed in the near future, and it is anticipated that the treatment outcomes of applicable cancers will be greatly improved by this treatment's excellent dose delivery characteristics.

• Progress in Medical Physics
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• v.8 no.1
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• pp.47-52
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• 1997

Simulations were performed using a Monte Carlo technique in order to show physical phenomena occurring when a heavy charged particle such as proton or alpha particle traverses the medium. It was confirmed that the sharp Bragg peak occurred deeper in the water with the increasing proton energy. It is found that the use of such a sharp Bragg peak due to heavy charged particles would be far superior to the case of the photon or electron, since the absorbed dose in the target tissues would be better localized, thereby minimizing the damage to the surrounding tissues.