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Effect of topogram-t…
Effect of topogram-tube angle combination on CT radiation do…

 This study assessed the ability of various types of topograms, when used with an automatic tube current modulation (ATCM) technique, to reduce radiation dose from computed tomography (CT) scans. Three types of topograms were used with the ATCM technique: (i) anteroposterior (AP) topograms alone, (ii) AP topograms followed by lateral topograms, and (iii) lateral topograms followed by AP topograms. Various regions (chest, abdomen and whole-body) of a humanoid phantom were scanned at several tube voltages (80, 100 and 120 kVp) with the selected topograms. Although the CT dose depended on the order of topograms, the CT dose with respect to patient positioning depended on the number of topograms performed. The magnitude of the difference in CT dose between number and order of topograms was greater for the scans of the abdomen than the chest. These results suggest that, for the Siemens SOMATOM Definition AS CT scanner, choosing the right combination of CT scan conditions with the ATCM technique can minimize radiation dose to a patient.

J. Shim and M. Yoon

Department of Bio-Convergence Engineering, Korea University,

145, Anam-ro, Seongbuk-gu, Seoul, Republic of Korea

Department of Diagnostic Radiology, Severance Hospital,

50-1, Yonsei-ro, Seodaemun-gu, Seoul, Republic of Korea

Journal of Instrumentation

Development of Beam …
Development of Beam Monitoring System for Proton Pencil Beam…
 We aimed to develop a beam monitoring system based on a fiber-optic radiation sensor (FORS),
which can be used in real time in a beam control room, to monitor a beam in proton therapy, where
patients are treated using a pencil beam scanning (PBS) mode, by measuring the beam spot width
(BSW) and beam spot position (BSP) of the PBS. We developed two-dimensional detector arrays to
monitor the PBS beam in the beam control room. We measured the BSW for five energies of the PBS
beam and compared the measurements with those of Lynx and EBT3 film. In order to confirm the
BSP, we compared the BSP values of the PBS calculated from radiation treatment planning (RTP),
to five BSP values measured using FORS at 224.2 MeV. When comparing BSW values obtained
using developed monitoring system to the measurements obtained using commercial EBT3 film, the
average difference in BSW value of the PBS beam was 0.1 ± 0.1 mm. In the comparison of BSW
values with the measurements obtained using Lynx, the average difference was 0.2 ± 0.1 mm. When
comparing BSP measurements to the values calculated from RTP, the average difference was 0.4 ±
0.2 mm. The study results confirmed that the developed FORS-based beam monitoring system can
monitor a PBS beam in real time in a beam control room, where proton beam is controlled for the

Jaeman Son,∗ Jihye Koo, Sunyoung Moon and Myonggeun Yoon
Department of Bio-convergence Engineering, Korea University, Seoul 10408, Korea
Jonghwi Jeong,∗ Sun-Young Kim, Youngkyung Lim, Se Byeong Lee and Dongho Shin
Proton Therapy Center, National Cancer Center, Goyang 02841, Korea
Meyoung Kim
Research Center, Dongnam Institute of Radiological & Medical Sciences (DIRAMS), Busan 46033, Korea
Dongwook Kim
Department of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Seoul 05278, Korea

Journal of the Korean Physical Society, Vol. 71, No. 7, October 2017, pp. 438∼443
Development of Optic…
Development of Optical Fiber Based Measurement System for th…
 This study describes the development of a beam monitoring system for the verification of entrance dose map in pencil beam scanning (PBS) proton therapy based on fiber optic radiation sensors (FORS) and the validation of this system through a feasibility study. The beam monitoring system consisted of 128 optical fibers optically coupled to photo-multiplier tubes. The performance of the beam monitoring system based on FORS was verified by comparing 2D dose maps of square-shaped fields of various sizes, which were obtained using conventional dosimeters such as MatriXX and EBT3 film, with those measured using FORS. The resulting full-width at half maximum and penumbra were compared for PBS proton beams, with a 2% difference between each value, indicating that measurements using the conventional dosimetric tool corresponded to measurements based on FORS. For irregularly-shaped fields, a comparison based on the gamma index between 2D dose maps obtained using MatriXX and EBT3 film and the 2D dose map measured by the FORS showed passing rates of 96.9  1.3% and 96.2  1.9%, respectively, confirming that FORS-based measurements for PBS proton therapy agreed well with those measured using the conventional dosimetric tools. These results demonstrate that the developed beam monitoring system based on FORS is good candidate for monitoring the entrance dose map in PBS proton therapy.

Jaeman Son 1, Se Byeong Lee 2, Youngkyung Lim 2, Sung Yong Park 3, Kwanho Cho 2, Myonggeun Yoon 1,* and Dongho Shin 2,*
1 Department of Bio-convergence Engineering, Korea University, Seoul 02841, Korea; jaeman0410@naver.com
2 Proton Therapy Center, National Cancer Center, Goyang 10408, Korea; sblee@ncc.re.kr (S.B.L.);
yklim@ncc.re.kr (Y.L.); kwancho@ncc.re.kr (K.C.)
3 Department of Medical Physics, Chinan Biomedical Technology Inc., Zhubei 30268, Taiwan;

Sensors 2018, 18, 227.
Study on the Dose Un…
Study on the Dose Uncertainties in the Lung during Passive P…
A moving phantom is manufactured for mimicking lung model to study the dose uncertainty from CT number-stopping power conversion and dose calculation in the soft tissue, light lung tissue and bone regions during passive proton irradiation with compensator smearing value. The phantom is scanned with a CT system, and a proton beam irradiation plan is carried out with the use of a treatment planning system (Eclipse). In the case of the moving phantom, a RPM system is used for respiratory gating. The uncertainties in the dose distribution between the measured data and the planned data are investigated by a gamma analysis with 3%-3 mm acceptance criteria. To investigate smearing effect, three smearing values (0.3 cm, 0.7 cm, 1.2 cm) are used to for fixed and moving phantom system. For both fixed and moving phantom, uncertainties in the light lung tissue are severe than those in soft tissue region in which the dose uncertainties are within clinically tolerable ranges. As the smearing value increases, the uncertainty in the proton dose distribution decreases.

Seung Hoon Yoo
Division of Heavy-Ion Clinical Research, Korea Institute of Radiological and Medical Science, Seoul 01812, Korea
Jae Man Son and Myonggeun Yoon
Department of Department of Bio-Convergence Engineering, Korea University, Seoul 02841, Korea
Sung Yong Park
McLaren Proton Therapy Center, McLaren Cancer Institute, Flint, Michigan 48532, USA
Dongho Shin
Proton Therapy Center, National Cancer Center, Goyang 10408, Korea
Byung Jun Min
Department of Radiation Oncology, Kangbuk Samsung Hospital,
Sungkyunkwan University School of Medicine, Seoul 03181, Korea

Journal of the Korean Physical Society, Vol. 72, No. 11, June 2018, pp. 1369∼1378
Toward a novel dosim…
Toward a novel dosimetry system using acrylic disk radiation…
Purpose: Fabricate an acrylic disk radiation sensor (ADRS) and characterize the photoluminescence
signal generated from the optical device as basis for the development and evaluation of a new
dosimetry system for pencil beam proton therapy.
Methods: Based on the characteristics of the proposed optical dosimetry sensor, we established the
relation between the photoluminescence output and the applied dose using an ionization chamber.
Then, we obtained the relative integral depth dose profiles using the photoluminescence signal generated
by pencil beam irradiation at energies of 99.9 and 162.1 MeV, and compared the results with the
curve measured using a Bragg peak ionization chamber.
Results: The relation between the photoluminescence output and applied dose was linear. In addition,
the ADRS was dose independent for beam currents up to 6 Gy/min, and the calibration factor
for energy was close to 1. Hence, the energy dependence on the optical device can be disregarded.
The integral depth dose profiles obtained for the ADRS suitable agreed with the curve measured in
the Bragg peak ionization chamber without requiring correction.
Conclusions: These results suggest that the ADRS is suitable for dosimetry measurements in pencil
beam scanning, and it will be employed as a low-cost and versatile dosimetry sensor in upcoming

Shinhaeng Cho
Proton Therapy Center, National Cancer Center, Goyang, Korea
Nuri Lee
Department of Radiation and Oncology, National Medical Center, Seoul, South Korea
Sanghyeon Song
Department of Radiation and Oncology, Soon Chun Hyang University Hospital, Seoul, South Korea
Jaeman Son
Department of Radiation and Oncology, Seoul National University Hospital, Seoul, South Korea
Haksoo Kim, Jong Hwi Jeong, Se Byeong Lee, and Youngkyung Lim
Proton Therapy Center, National Cancer Center, Goyang, Korea
Sunyoung Moon and Myonggeun Yoon
Department of Bio-Convergence Engineering, Korea University, Seoul, Korea
Dongho Shina)
Proton Therapy Center, National Cancer Center, Goyang, Korea

Med. Phys. 45(11), November 2018

Quantitative study o…
Quantitative study of fast non-local means-based denoising f…
In chest radiography, a solitary pulmonary nodule, which may be a precursor of lung cancer, is a frequently detected finding. However, as the image quality is deteriorated owing to the increase in the noise, lung cancer screening studies revealed that the likelihood of finding a nodule is lower than those of other modalities. This study quantitatively evaluates three widely used filters (median, Wiener, and total variation) and a newly proposed filter (fast non-local means (FNLM)), which reduce image noise. Images of a phantom with lung nodules, obtained from a patient using the 3D printing technology, were acquired at the chest anterior–posterior, lateral, and posterior– anterior positions. To evaluate their denoising performance, normalized noise power spectrum, contrast to noise ratio and coefficient of variation were used. In the quantitative evaluation
of the overall image, the proposed FNLM filter exhibited the best image performance. In the quantitative evaluation of the nodule image, the FNLM filter, which exhibits outstanding denoising performance and time efficiency, can be employed. Therefore, with the use of the FNLM filter in chest radiography, the detection probability of a nodule, which can be a precursor of lung
cancer, is increased, and the cancer can be prevented even with a lower dose. 

Jina Shim, Myonggeun Yoon, Youngjin Lee
a Department of Bio-Convergence Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, Republic of Korea
b Department of Diagnostic Radiology, Severance Hospital, 50-1, Yonsei-ro, Seodaemun-gu, Seoul, Republic of Korea
c Department of Radiological Science, Gachon University, 191, Hambakmoero, Yeonsu-gu, Incheon, Republic of Korea

Optik - International Journal for Light and Electron Optics 179(2019)
Effectiveness of a F…
Effectiveness of a Fractionated Therapy Scheme in Tumor Trea…
  This study aimed to evaluate the biological effectiveness of cancer therapy with tumor treating fields using a fractionated
treatment scheme that was originally designed for radiotherapy. Discontinuous fractional tumor treating fields of an intensity of
0.9 to 1.2 V/cm and a frequency of 150 KHz were applied to U373 cancer cells and IEC6 normal cells for 3 days, with durations of 3, 6, 12, or 24 h/d. As the treatment duration of the tumor treating fields increased from 3 to 24 h/d, the relative tumor cell (U373) number (% of control) reduced in proportion to the treatment duration. Compared to a 25% cell number reduction (75% of
control) for the group of 6 h/d treatment at 1.2 V/cm, only 5% (70% of control) and 8% (67% of control) of additional reductions
were observed for the group of 12 and 24 h/d treatment, respectively. This experimental result indicates that the dependence on
treatment duration in tumor cell inhibition was weakened distinctly at treatment duration over 6 h/d. For normal cells (IEC6), the
relative cell number corresponding to the treatment time of the tumor treating fields at 1.2 V/cm of electric field strength was not
decreased much for the treatment times of 3, 6, and 12 h/d, revealing 93.3%, 90.0%, and 89.3% relative cell numbers, respectively, but it suddenly decreased to *73% for the 24 h/d treatment. Our results showed that the effects of tumor treating fields on tumor cells were higher than on normal cells for treatment duration of 3 to 12 h/d, but the difference became minimal for treatment duration of 24 h/d. The fractionated scheme, using tumor treating fields, reduced the treatment time while maintaining efficacy, suggesting that this method may be clinically applicable for cancer treatment.

Yunhui Jo, BS1,2, Jiwon Sung, PhD1, Hyesun Jeong, MS3,
Sunghoi Hong, PhD3, Youn Kyoung Jeong, PhD4, Eun Ho Kim, PhD2, and
Myonggeun Yoon, PhD1

Technology in Cancer Research & Treatment
Volume 18: 1-10 The Author(s) 2019

Tumor-treating field…
Tumor-treating fields induce autophagy by blocking the Akt2/…
  Tumor-treating fields (TTFs) — a type of electromagnetic field-based therapy using low-intensity electrical fields — has
recently been characterized as a potential anticancer therapy for glioblastoma multiforme (GBM). However, the molecular
mechanisms involved remain poorly understood. Our results show that the activation of autophagy contributes to the TTFinduced anti-GBM activity in vitro or in vivo and GBM patient stem cells or primary in vivo culture systems. TTF-treatment
upregulated several autophagy-related genes (~2-fold) and induced cytomorphological changes. TTF-induced autophagy in
GBM was associated with decreased Akt2 expression, not Akt1 or Akt3, via the mTOR/p70S6K pathway. An Affymetrix
GeneChip miRNA 4.0 Array analysis revealed that TTFs altered the expression of many microRNAs (miRNAs). TTFinduced
autophagy upregulated miR-29b, which subsequently suppressed the Akt signaling pathway. A luciferase reporter assay confirmed that TTFs induced miR-29b to target Akt2, negatively affecting Akt2 expression thereby triggering autophagy. TTF-induced autophagy suppressed tumor growth in GBM mouse models subjected to TTFs as determined by positron emission tomography and computed tomography (PET-CT). GBM patient stem cells and a primary in vivo culture system with high Akt2 levels also showed TTF-induced inhibition. Taken together, our results identified autophagy as a critical cell death pathway triggered by TTFs in GBM and indicate that TTF is a potential treatment option for GBM.

Eun Ho Kim, Yunhui Jo1,2 , Sei Sai3 , Mung-Jin Park1 , Jeong-Yub Kim1, Jin Su Kim4, Yeon-Joo Lee 1,
Jae-Min Cho1, Seo-Young Kwak5, Jeong-Hwa Baek1, Youn Kyoung Jeong6, Jie-Young Song 1,
Myonggeun Yoon2, Sang-Gu Hwang1

Oncogene (2019) 38:6630–6646

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
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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