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Secondary neutron do…
Secondary neutron dose measurement for proton eye treatment …
Background: We measured and assessed ways to reduce the secondary neutron dose from a system for proton
eye treatment.
Methods: Proton beams of 60.30 MeV were delivered through an eye-treatment snout in passive scattering mode.
Allyl diglycol carbonate (CR-39) etch detectors were used to measure the neutron dose in the external field at 0.00,
1.64, and 6.00 cm depths in a water phantom. Secondary neutron doses were measured and compared between
those with and without a high-hydrogen?boron-containing block. In addition, the neutron energy and vertices
distribution were obtained by using a Geant4 Monte Carlo simulation.
Results: The ratio of the maximum neutron dose equivalent to the proton absorbed dose (H(10)/D) at 2.00 cm
from the beam field edge was 8.79 ± 1.28 mSv/Gy. The ratio of the neutron dose equivalent to the proton
absorbed dose with and without a high hydrogen-boron containing block was 0.63 ± 0.06 to 1.15 ± 0.13 mSv/Gy at
2.00 cm from the edge of the field at depths of 0.00, 1.64, and 6.00 cm.
Conclusions: We found that the out-of-field secondary neutron dose in proton eye treatment with an eye snout is
relatively small, and it can be further reduced by installing a borated neutron absorbing material.
 
 
 
Dong Wook Kim1, Weon Kuu Chung1, Jungwook Shin2, Young Kyung Lim3, Dongho Shin3*, Se Byeong Lee3,
Myongguen Yoon4, Sung-Yong Park5, Dong Oh Shin6 and Jung Keun Cho7
1Department of Radiation Oncology, Kyung Hee University Hospital at
Gandong, Seoul, Korea. 2Radiation Oncology, University of California, San
Francisco, USA. 3Proton Therapy Center, National Cancer Center, Ilsan, Korea.
4Department of Radiological Science, Korea University, Seoul, Korea. 5Proton
Therapy Center, McLaren Cancer Institute, Flint, MI, USA. 6Department of
Radiation Oncology, Kyung Hee University Medical Center, Seoul, Korea.
7Department of Radiological Science, Jeonju University, Jeonju, Korea.
 
Kim et al. Radiation Oncology 2013, 8:182
Development of a nov…
Development of a novel proton dosimetry system using an arra…
This study describes the development and evaluation of a new dosimetric system for proton therapy
using an array of fiber-optic Cerenkov radiation sensors (AFCRS). The AFCRS was superior to a conventional,
multi-layer ion chamber (MLIC) system in real-time data acquisition and cost effectiveness.
 
 
 
 
Jaeman Son a,b, Meyoung Kim c, Dongho Shin a,?, Uijung Hwang d, Sebyeong Lee a, Youngkyung Lim a,
Jeonghoon Park a, Sung yong Park e, Kwanho Cho a, Daeyong Kim a, Kyoung Won Jang f,
Myonggeun Yoon b,?
a Proton Therapy Center, National Cancer Center, Goyang; b Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea; c Research Center,
Dongnam Institute of Radiological & Medical Sciences, Busan, Republic of Korea; d Radiation Oncology, National Medical Center, Seoul; e Great Lakes Cancer Institute, McLaren
Regional Medical Center, Flint, USA; and f Department of Medical Engineering, Konkuk University, Chungju, Republic of Korea
 
Son J et al. Development of a novel proton dosimetry system using an array of fiber-optic Cerenkov radiation sensors.
Radiother Oncol (2015)
Feasibility Study of…
Feasibility Study of a Simple Approximation Algorithm for In…
The purpose of this study is to verify the accuracy of the dose delivered to the patient during
intensity-modulated radiation therapy (IMRT) by using in-vivo dosimetry and to avoid accidental
exposure to healthy tissues and organs close to tumors. The in-vivo dose was reconstructed by
back projection of the transit dose with a simple approximation that considered only the percent
depth dose and inverse square law. While the average gamma index for comparisons of dose distributions
between the calculated dose map and the film measurement was less than the one for
96.3% of all pixels with the homogeneous phantom, the passing rate was reduced to 92.8% with the
inhomogeneous phantom, suggesting that the reduction was apparently due to the inaccuracy of the
reconstruction algorithm for inhomogeneity. The proposed method of calculating the dose inside
a phantom was of comparable or better accuracy than the treatment planning system, suggesting
that it can be used to verify the accuracy of the dose delivered to the patient during treatment.
 
 
Ui-Jung Hwang and Mi Hee Song
Department of Radiation Oncology, National Medical Center, Seoul, Korea
Tae Seong Baek and Eun Ji Chung
Department of Radiation Oncology, National Health Insurance Corporation Ilsan Hospital, Ilsan, Korea
Myonggeun Yoon?
Department of Bio-convergence Engineering, Korea University, Seoul 136-703, Korea
 
Journal of the Korean Physical Society, Vol. 66, No. 4, February 2015, pp. 694∼699
 
Risk of secondary ca…
Risk of secondary cancers from scattered radiation during in…
Purpose: To evaluate and compare the risks of secondary cancers from therapeutic doses received by patients with
hepatocellular carcinoma (HCC) during intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT), and
tomotherapy (TOMO).
Methods: Treatments for five patients with hepatocellular carcinoma (HCC) were planned using IMRT, VMAT, and
TOMO. Based on the Biological Effects of Ionizing Radiation VII method, the excess relative risk (ERR), excess
absolute risk (EAR), and lifetime attributable risk (LAR) were evaluated from therapeutic doses, which were
measured using radiophotoluminescence glass dosimeters (RPLGDs) for each organ inside a humanoid phantom.
Results: The average organ equivalent doses (OEDs) of 5 patients were measured as 0.23, 1.18, 0.91, 0.95, 0.97, 0.24,
and 0.20 Gy for the thyroid, lung, stomach, liver, small intestine, prostate (or ovary), and rectum, respectively. From
the OED measurements, LAR incidence were calculated as 83, 46, 22, 30, 2 and 6 per 104 person for the lung,
stomach, normal liver, small intestine, prostate (or ovary), and rectum.
Conclusions: We estimated the secondary cancer risks at various organs for patients with HCC who received
different treatment modalities. We found that HCC treatment is associated with a high secondary cancer risk in the
lung and stomach.
 
 
 
Dong Wook Kim1, Kwangzoo Chung2, Weon Kuu Chung1, Sun Hyun Bae1, Dong Oh Shin3, Seongeon Hong3,
Sung Ho Park4, Sung-Yong Park5, Chae-Seon Hong2, Young Kyung Lim6, Dongho Shin6, Se Byeong Lee6,
Hyun-ho Lee7, Jiwon Sung7 and Myonggeun Yoon7*
1Department of Radiation Oncology, KyungHee University Hospital at
Gangdong, Seoul, Korea. 2Deparment of Radiation Oncology, Samsung
Medical Center, Seoul, Korea. 3Department of Radiation Oncology, KyungHee
University Medical Center, Seoul, Korea. 4Department of Neurosurgery, Ulsan
University Hospital, Ulsan, Korea. 5Proton Therapy Center, McLaren Cancer
Institute, Flint, USA. 6Proton Therapy Center, National Cancer Center, Ilsan,
Korea. 7Department of Radiological Science, College of Health Science, Korea
University, Jeongneung 3-dong, Seongbuk-gu, Seoul, Korea.
 
 
Kim et al. Radiation Oncology 2014, 9:109
 
Inhibition of brain …
Inhibition of brain tumor cell proliferation by alternating …
This study was designed to investigate the mechanism by which electric fields affect cell function,
and to determine the optimal conditions for electric field inhibition of cancer cell proliferation.
Low-intensity (<2 V/cm) and intermediate-frequency (100?300 kHz) alternating electric fields
were applied to glioblastoma cell lines. These electric fields inhibited cell proliferation by inducing
cell cycle arrest and abnormal mitosis due to the malformation of microtubules. These effects were
significantly dependent on the intensity and frequency of applied electric fields.
 
 
 
 
Hyesun Jeong,1,a) Jiwon Sung,2,a) Seung-ick Oh,1 Seonghoon Jeong,2 Eui Kwan Koh,3
Sunghoi Hong,1,b) and Myonggeun Yoon2,b)
1School of Biosystem and Biomedical Science, Korea University, Seoul 136-703, South Korea
2Department of Bio-convergence Engineering, Korea University, Seoul 136-703, South Korea
3Seoul Center, Korea Basic Science Institute, Seoul 136-713, South Korea
 
APPLIED PHYSICS LETTERS 105, 203703 (2014)
Feasibility study on…
Feasibility study on the verification of actual beam deliver…
Purpose: The aim of this study is to evaluate the ability of transit dosimetry using commercial treatment planning
system (TPS) and an electronic portal imaging device (EPID) with simple calibration method to verify the beam
delivery based on detection of large errors in treatment room.
Methods and materials: Twenty four fields of intensity modulated radiotherapy (IMRT) plans were selected from
four lung cancer patients and used in the irradiation of an anthropomorphic phantom. The proposed method was
evaluated by comparing the calculated dose map from TPS and EPID measurement on the same plane using a
gamma index method with a 3% dose and 3 mm distance-to-dose agreement tolerance limit.
Results: In a simulation using a homogeneous plastic water phantom, performed to verify the effectiveness of the
proposed method, the average passing rate of the transit dose based on gamma index was high enough, averaging
94.2% when there was no error during beam delivery. The passing rate of the transit dose for 24 IMRT fields was lower
with the anthropomorphic phantom, averaging 86.8% ± 3.8%, a reduction partially due to the inaccuracy of TPS
calculations for inhomogeneity. Compared with the TPS, the absolute value of the transit dose at the beam center
differed by ?0.38% ± 2.1%. The simulation study indicated that the passing rate of the gamma index was significantly
reduced, to less than 40%, when a wrong field was erroneously irradiated to patient in the treatment room.
Conclusions: This feasibility study suggested that transit dosimetry based on the calculation with commercial TPS and
EPID measurement with simple calibration can provide information about large errors for treatment beam delivery.
 
 
 
Tae Seong Baek1,2, Eun Ji Chung2, Jaeman Son1 and Myonggeun Yoon1*
1Department of Bio-convergence Engineering, Korea University,
Jeongneungro 161, Seongbuk-gu, Seoul 136-703, Korea. 2Department of
Radiation Oncology, National Health Insurance Co. Ilsan Hospital, Ilsan, Korea.
 
Baek et al. Radiation Oncology 2014, 9:273
Secondary cancer-inc…
Secondary cancer-incidence risk estimates for external radio…
 This study was designed to estimate radiation-induced secondary cancer risks from high-dose-rate (HDR) brachytherapy and external radiotherapy for patients with cervical cancer based on measurements of doses absorbed by various organs. Organ doses from HDR brachytherapy and external radiotherapy were measured using glass rod dosimeters. Doses to out-of-field organs were measured at various locations inside an anthropomorphic phantom. Brachytherapy-associated organ doses were measured using a specialized phantom that enabled applicator insertion, with the pelvis portion of the existing anthropomorphic phantom replaced by this new phantom. Measured organ doses were used to calculate secondary cancer risk based on Biological Effects of Ionizing Radiation (BEIR) VII models. In both treatment modalities, organ doses per prescribed dose (PD) mostly depended on the distance between organs. The locations showing the highest and lowest doses were the right kidney (external radiotherapy: 215.2 mGy; brachytherapy: 655.17 mGy) and the brain (external radiotherapy: 15.82 mGy; brachytherapy: 2.49 mGy), respectively. Organ doses to nearby regions were higher for brachytherapy than for external beam therapy, whereas organ doses to distant regions were higher for external beam therapy. Organ doses to distant treatment regions in external radiotherapy were due primarily to out-of-field radiation resulting from scattering and leakage in the gantry head. For brachytherapy, the highest estimated lifetime attributable risk per 100,000 population was to the stomach (88.6), whereas the lowest risks were to the brain (0.4) and eye (0.4); for external radiotherapy, the highest and lowest risks were to the thyroid (305.1) and brain (2.4). These results may help provide a database on the impact of radiotherapy-induced secondary cancer incidence during cervical cancer treatment, as well as suggest further research on strategies to counteract the risks of radiotherapy-associated secondary malignancies.

Boram Lee,1,2 Sung Hwan Ahn,2 Hyeyoung Kim,2 Jaeman Son,1
Jiwon Sung,1 Youngyih Han,3 Seung Jae Huh,3 Jin Sung Kim,4
Dong Wook Kim,5 and Myonggeun Yoon1a
Department of Bio-convergence Engineering,1 Korea University, Seoul; Department of Radiation Oncology,2 Samsung Medical Center, Seoul; Department of Radiation Oncology,3 Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; Department of Radiation Oncology,4 College of Medicine, Yonsei Cancer Center, Seoul; Department of Radiation Oncology,5 Kyung Hee University Hospital at Gangdong, Seoul, Korea

Journal of Applied Clinical Medical Physics 17.5 (2016).
Development and curr…
Development and current status of proton therapy for lung ca…
 The aim of this study was to examine the current status of proton therapy in Korea and to review the dosimetric benefits of proton beam therapy (PBT) over intensitymodulated radiotherapy (IMRT) for lung cancer treatment. Data from patients treated betweenMarch 2007 and February 2011 in Korea using proton therapy were analyzed retrospectively. For comparison, IMRT and PBT in the scattering mode were planned for lung cancer patients. Dosimetric benefits and organ-specific radiation-induced cancer risks were based on comparisons of dose volume histograms (DVH) and secondary radiation doses, respectively. On average, the doses delivered by PBT to the lung, esophagus and spinal cord were 17.4%, 2.5% and 43.6% of the prescription dose, respectively, which were lower than the doses delivered by IMRT (31.5%, 11.8% and 45.3%, respectively). Although the average doses delivered by PBT to the lung and spinal cord were significantly lower than those by IMRT, these differences were reduced in the esophagus.While the average secondary dose from PBT (measured at 20?50 cm from the isocenter) was 1.33?0.86 mSv/Gy, the average secondary dose from IMRT was 3.3?1.0 mSv/Gy. Compared with IMRT techniques, PBT showed improvements in most dosimetric parameters for lung cancer patients,with lower secondary radiation doses.
 
 
 
 
Myonggeun Yoon
Department of Radiological Science, College of Health Science, Yonsei University, Wounju, Korea
 
Thoracic Cancer ISSN 1759-7706
Radiochromic film ba…
Radiochromic film based transit dosimetry for verification o…
Purpose: To evaluate the transit dose based patient specific quality assurance (QA) of intensity
modulated radiation therapy (IMRT) for verification of the accuracy of dose delivered to the
patient.
Methods: Five IMRT plans were selected and utilized to irradiate a homogeneous plastic water phantom
and an inhomogeneous anthropomorphic phantom. The transit dose distribution was measured
with radiochromic film and was compared with the computed dose map on the same plane using a
gamma index with a 3% dose and a 3 mm distance-to-dose agreement tolerance limit.
Results: While the average gamma index for comparisons of dose distributions was less than one
for 98.9% of all pixels from the transit dose with the homogeneous phantom, the passing rate was
reduced to 95.0% for the transit dose with the inhomogeneous phantom. Transit doses due to a 5 mm
setup error may cause up to a 50% failure rate of the gamma index.
Conclusions: Transit dose based IMRT QA may be superior to the traditional QA method since the
former can show whether the inhomogeneity correction algorithm from TPS is accurate. In addition,
transit dose based IMRT QA can be used to verify the accuracy of the dose delivered to the patient
during treatment by revealing significant increases in the failure rate of the gamma index resulting
from errors in patient positioning during treatment. ? 2013 American Association of Physicists in
Medicine.
 
 
 
Kwangzoo Chung
Proton Therapy Center, National Cancer Center, Goyang 410-769, Korea
Myonggeun Yoona) and Jaeman Son
Department of Radiological Science, College of Health Science, Korea University, Seoul 136-703, Korea
Sung Yong Park
Proton Therapy Center, McLaren Cancer Institute, Flint, Michigan 48532
Kiho Lee, Dongho Shin, Young Kyung Lim, and Se Byeong Lee
Proton Therapy Center, National Cancer Center, Goyang 410-769, Korea
 
Med. Phys. 40 (2), February 2013
Tumor treating field…
Tumor treating fields inhibit glioblastoma cell migration, i…
 Treatment with alternating electric fields at an intermediate frequency (100?300 kHz), referred to as tumor treating fields (TTF) therapy, inhibits cancer cell proliferation. In the present study, we demonstrated that TTF application suppressed the metastatic potential of U87 and U373 glioblastoma cell lines via the NF-kB, MAPK and PI3K/AKT signaling pathways. Wound-healing and transwell assays showed that TTF suppressed cell migration and invasion compared with controls. Soft agar and three-dimensional culture assays showed that TTF inhibited both anchoragedependent (cell proliferation) and anchorage-independent (colony formation) GBM cell growth. TTF dysregulated epithelial-to-mesenchymal transition-related genes, such as vimentin and E-cadherin, which partially accounted for TTF inhibition of cell migration and invasion. We further demonstrated that TTF application suppressed angiogenesis by downregulating VEGF, HIF1α and matrix metalloproteinases 2 and 9. TTF also inhibited NF-kB transcriptional activity. Collectively, our findings show that TTF represents a promising novel anti-invasion and anti-angiogenesis therapeutic strategy for use in GBM patients.

Eun Ho Kim1, Hyo Sook Song2, Seung Hoon Yoo1, Myonggeun Yoon2
1Korea Institute of Radiological and Medical Sciences, Seoul, Korea
2Department of Bio-Convergence Engineering, Korea University, Seoul, Korea

Oncotarget 7.40 (2016): 65125-65136.
Biological effect of…
Biological effect of an alternating electric field on cell p…
Alternating electric fields at an intermediate frequency (100~300 kHz), referred to as tumour-treating fields (TTF), are believed to interrupt the process of mitosis via apoptosis and to act as an inhibitor of cell proliferation. Although the existence of an antimitotic effect of TTF is widely known, the proposed apoptotic mechanism of TTF on cell function and the efficacy of TTF are controversial issues among medical experts. To resolve these controversial issues, a better understanding of the underlying molecular mechanisms of TTF on cell function and the differences between the effects of TTF alone and in combination with other treatment techniques is essential. Here, we report experimental evidence of TTF-induced apoptosis and the synergistic antimitotic effect of TTF in combination with ionizing radiation (IR). For these experiments, two human Glioblastoma multiforme (GBM) cells (U373 and U87) were treated either with TTF alone or with TTF followed by ionizing radiation (IR). Cell apoptosis, DNA damage, and mitotic abnormalities were quantified after the application of TTF, and their percentages were markedly increased when TTF was combined with IR. Our experimental results also suggested that TTF combined with IR synergistically suppressed both cell migration and invasion, based on the inhibition of MMP-9 and vimentin.

Eun Ho Kim1, Ye Jin Kim1, Hyo Sook Song2, Youn Kyoung Jeong1, Ji Young Lee1,
Jiwon Sung2, Seung Hoon Yoo1, Myonggeun Yoon2
1Korea Institute of Radiological & Medical Sciences, Seoul, 01812, Korea
2Department of Bio-Convergence Engineering, Korea University, Seoul, 02841, Korea

Oncotarget 7.38 (2016): 62267-62279.
Three-dimensional ra…
Three-dimensional radiochromic film dosimetry of proton clin…
 
 In this work, three-dimensional (3D) film-based proton beam measurements were used for the first time to verify the patientspecific radiation dose distribution, beam range and compensator shape. Three passively scattered proton beams and one uniform scanning proton beam were directed onto an acrylic phantom with inserted Gafchromic EBT films. The average gamma index for a comparison of the dose distributions was less than one for 97.2 % of all pixels from the passively scattered proton beams and 98.1 % of all pixels for the uniform scanning proton beams, with a 3 % dose and a 3 mm distance-to-dose agreement tolerance limit. The results also showed that the average percentage of points within the acceptance criteria for proton beam ranges was 94.6 % for the passively scattered proton beams. Both the dose distribution and the proton beam range determined by the 3D EBT film measurement agreed well with the planning system values.
 
 
 
Jinsung Kim1, Myonggeun Yoon2,*, Seonkyu Kim3, Dongho Shin3, Se Byeong Lee3, Young Kyung Lim3,
Dong Wook Kim4 and Sung Yong Park5
1Department of Radiation Oncology, Samsung Medical Center, Seoul, Korea
2Department of Radiological Science, College of Health Science, Korea University, Seoul, Korea
3Proton Therapy Center, National Cancer Center, 809 Madu 1-dong, Ilsandong-gu, Goyang, Korea
4Department of Radiation Oncology, Kyung Hee University Hospital at Kangdong, Seoul, Korea
5McLaren Regional Medical Center, Great Lakes Cancer Institute, Flint, MI, USA

Radiation Protection Dosimetry (2012), Vol. 151, No. 2, pp. 272?277
Eye tracking and gat…
Eye tracking and gating system for proton therapy of orbital…
Purpose: A new motion-based gated proton therapy for the treatment of orbital tumors using
real-time eye-tracking system was designed and evaluated.
Methods:We developed our system by image-pattern matching, using a normalized cross-correlation
technique with LabVIEW 8.6 and Vision Assistant 8.6 (National Instruments, Austin, TX). To
measure the pixel spacing of an image consistently, four different calibration modes such as the
point-detection, the edge-detection, the line-measurement, and the manual measurement mode were
suggested and used. After these methods were applied to proton therapy, gating was performed, and
radiation dose distributions were evaluated.
Results: Moving phantom verification measurements resulted in errors of less than 0.1 mm for given
ranges of translation. Dosimetric evaluation of the beam-gating system versus nongated treatment
delivery with a moving phantom shows that while there was only 0.83 mm growth in lateral penumbra
for gated radiotherapy, there was 4.95 mm growth in lateral penumbra in case of nongated exposure.
The analysis from clinical results suggests that the average of eye movements depends distinctively
on each patient by showing 0.44 mm, 0.45 mm, and 0.86 mm for three patients, respectively.
Conclusions: The developed automatic eye-tracking based beam-gating system enabled us to perform
high-precision proton radiotherapy of orbital tumors. ? 2012 American Association of Physicists in
Medicine.
 
 
 
Dongho Shin
Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi 410-769, Republic of Korea
Seung Hoon Yoo
Department of Radiation Oncology, CHA Bundang Medical Center, CHA University,
Seongnam, Gyeonggi 463-712, Republic of Korea
Sung Ho Moon
Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi 410-769, Republic of Korea
Myonggeun Yoon
Department of Radiological Science, Korea University, Seoul 136-703, Republic of Korea
Se Byeong Lee
Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi 410-769, Republic of Korea
Sung Yong Parka)
Proton Therapy Center, McLaren Cancer Institute, Flint, Michigan 48532
 
Medical Physics, Vol. 39, No. 7, July 2012
Feasibility Study of…
Feasibility Study of Patient-specific Quality Assurance Syst…

 This study was conducted for the purpose of establishing a quality-assurance (QA) system for brachytherapy that can ensure patient-specific QA by enhancing dosimetric accuracy for the patient’s therapy plan. To measure the point-absorbed dose and the 2D dose distribution for the patient’s therapy plan, we fabricated a solid phantom that allowed for the insertion of an applicator for patient-specific QA and used an ion chamber and a film as measuring devices. The patient treatment plan was exported to the QA dose-calculation software, which calculated the time weight of dwell position stored in the plan DICOM (Digital Imaging and Communications in Medicine) file to obtain an overall beam quality correction factor, and that correction was applied to the dose calculations. Experiments were conducted after importing the patient’s treatment planning source data for the fabricated phantom and inserting the applicator, ion chamber, and film into the phantom. On completion of dose delivery, the doses to the ion chamber and film were checked against the corresponding treatment plan to evaluate the dosimetric accuracy. For experimental purposes, five treatment plans were randomly selected. The beam quality correction factors for ovoid and tandem brachytherapy applicators were found to be 1.15 and 1.10 ? 1.12, respectively. The beam quality correction factor in tandem fluctuated by approximately 2%, depending on the changes in the dwell position. The doses measured by using the ion chamber showed differences ranging from ?2.4% to 0.6%, compared to the planned doses. As for the film, the passing rate was 90% or higher when assessed using a gamma value of the local dose difference of 3% and a distance to agreement of 3 mm. The results show that the self-fabricated phantom was suitable for QA in clinical settings. The proposed patient-specific QA for the treatment planning is expected to contributeto reduce dosimetric errors in brachytherapy and, thus, to enhancing treatment accuracy. 

Boram Lee
Department of Bio-convergence Engineering, Korea University, Seoul 02841, Korea, and
Department of Radiation Oncology, Samsung Medical Center,
Sungkyunkwan University School of Medicine, Seoul 06351, Korea
Sung Hwan Ahn, Hyeyoung Kim, Youngyih Han and Seung Jae Huh
Department of Radiation Oncology, Samsung Medical Center,
Sungkyunkwan University School of Medicine, Seoul 06351, Korea
Jin Sung Kim
Department of Radiation Oncology, Yonsei University College of Medicine, Yonsei Cancer Center, Seoul 03722, Korea
Dong Wook Kim
Department of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Seoul 05278, Korea
Jina Sim and Myonggeun Yoon?
Department of Bio-convergence Engineering, Korea University, Seoul 02841, Korea

Journal of the Korean Physical Society, Vol. 68, No. 8, April 2016
Feasibility study of…
Feasibility study of a plastic scintillating plate-based tre…
Purpose: The purpose of this study was to describe a plastic scintillating plate-based gantryattachable
dosimetry system for pencil beam scanning proton therapy to monitor entrance proton beam
fluence, and to evaluate the dosimetric characteristics of this system and its feasibility for clinical use.
Methods: The dosimetry system, consisting of a plastic scintillating plate and a CMOS camera, was
attached to a dedicated scanning nozzle and scintillation during proton beam irradiation was
recorded. Dose distribution was calculated from the accumulated recorded frames. The dosimetric
characteristics (energy dependency, dose linearity, dose rate dependency, and reproducibility) of the
gantry-attachable dosimetry system for use with therapeutic proton beams were measured, and the
feasibility of this system during clinical use was evaluated by determining selected quality assurance
items at our institution.
Results: The scintillating plate shortened the range of the proton beam by the water-equivalent thickness
of the plate and broadened the spatial profile of the single proton spot by 11% at 70 MeV. The
developed system functioned independently of the beam energy (<1.3%) and showed dose linearity,
and also functioned independently of the dose rate. The feasibility of the system for clinical use was
evaluated by comparing the measured quality assurance dose distribution to that of the treatment
planning system. The gamma passing rate with a criterion of 3%/3 mm was 97.58%.
Conclusions: This study evaluated the dosimetric characteristics of a plastic scintillating plate-based
dosimetry system for use with scanning proton beams. The ability to account for the interference of
the dosimetry system on the therapeutic beam enabled offline monitoring of the entrance beam fluence
of the pencil beam scanning proton therapy independent of the treatment system with high resolution
and in a cost-effective manner.

Seonghoon Jeong
Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea
Kwangzoo Chung, Sung Hwan Ahn, and Boram Lee
Department of Radiation Oncology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Republic of
Korea
Jaehyeon Seo and Myonggeun Yoon
Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea

Med. Phys. 47 (2), February 2020.

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