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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
 
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
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
 
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
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
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
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
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
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