| Potential prognostic factor in alternating electric fields t…The present study aimed
to determine a method for estimating a potential prognostic factor in
alternating electric fields for the treatment of solid tumors based on cell
survival curves that evaluate cell proliferation capability. In AGS, B16F10,
U373, and HPAF-II cancer cell lines, the proportional relationships of the
electric field magnitude and the duration of application with the proliferation
of cancer cell lines was identified by in
vitro alternating current electric field experiments performed
under various conditions. A prognostic factor applicable to alternating
electric field therapy was developed by identifying proportional relationships
of the electric field magnitude and the duration of application with the
proliferation of the four cancer cell lines. Through the experimental results,
the absorbed energy in tissue has been suggested as a potential prognostic
factor in alternating electric field therapy. The absorbed energy in tissue can
be used as a reference to quantify the inhibition of cell proliferation related
to control, enabling systematic assessment of alternating electric field
therapy which, to date, has not been possible.
Geon Oh, Yongha Gi, Heehun Sung, Jaehyun Seo, Hyunwoo Kim
Department of Bioengineering, Korea University, Seoul 02841,Republic of Korea
Yunhui Jo
Institute of Global Health Technology(IGHT), Korea University, Seoul 02841, Republic of Korea
Jaemin Lee
Department of Internal Medicine, Anam Hospital, Korea University College of Medicine, Seoul 02841, Republic of Korea
Myonggeun Yoon
Department of Bioengineering, Korea University, Seoul 02841,Republic of Korea
FieldCure Ltd.,Seoul 02852, Republic of Korea
AIPAdvances12,095311(2022) |
|
|
| Feasibility of a method for optimizing the electrode array s…The
present study investigated electrode array structures that maximize the
therapeutic electric field intensity to tumors with different shapes and
locations, while minimizing electric field intensity to the surrounding organs
at risk (OARs). A human body phantom model was created from magnetic resonance
images of a patient and divided into regions including a tumor and OARs. The
shapes and sizes of the electrode arrays were altered for tumors differing in
shape and location, and these electrode array structures were tested in the
phantom. Use of a conformal electrode array based on the shape of the tumor
maintained therapeutic electric field intensity to the tumor while reducing
electric field intensity to the surrounding OARs by approximately 18%. Although
the electric field intensity delivered to the tumor was proportional to the
size of the electrode array, it was saturated at a critical area. Simulation
results showed that optimal sizes of electrode arrays for specific tumors
located at depths of 2 cm, 4 cm and 6 cm were 91, 273 and 830 cm2,
respectively, indicating that the optimal size of the electrode array is
proportional to the depth of tumor in the phantom. These results suggest that a
tumor location-dependent optimal ratio between the size of the electrode array
and the size of the individual electrodes could be calculated. In summary, this
study indicated that customizing the electrode array structure to individual
tumors can markedly increase the electric field intensity delivered to the
tumor while minimizing the intensity delivered to OARs.
Geon Oh, Yongha Gi, Heehun Sung, Hyunwoo Kim, Jaehyeon Seo & Myonggeun Yoon
Department of Bioengineering, Korea
University, Seoul, 02841, Republic of Korea
Myonggeun Yoon
FieldCure Ltd, Seoul, 02481, Republic of
Korea
Yunhui Jo
Institute of Global Health Technology,
Korea University, Seoul, 02841, Republic of Korea
J. Korean Phys. Soc. 81, 1020–1028
(2022). |
| |
| Feasibility of a quality assurance system for electromagneti…This
study was designed to evaluate the effectiveness of a newly developed quality
assurance system for electromagnetic field therapy called tumor treating fields
therapy, which uses an alternating electric field to treat cancer based on an
intermediate frequency of 100–300 kHz. The quality assurance system for
electromagnetic field therapy consisted of a water phantom, a probe, and a
digital data acquisition (DAQ) board. Low intensity alternating electric fields
(200 kHz, 0–.1 V/cm) were created within the water phantom using a function
generator and a high voltage amplifier. The electric potential formed inside
the water phantom was measured using the probe and DAQ board. The electric
field intensity was derived by measuring the electric potential at the 190
points (19 × 10 cm2) of the midplane. Accuracy was evaluated by
gamma index analysis, which compared the measured electric field and the
simulation result. The mean difference between the simulation result and the
measured electric potentials within the water phantom was 0.31 V. The gamma
passing rate for the tolerance levels of 0.5 V/5 mm was 95.5% for electric
potential comparison showing good agreement between simulation and experimental
results. The mean difference between the electric field distribution within the
water phantom and the simulated values was 0.09 V/cm and the gamma passing rate
for the tolerance levels of (0.2 V/cm)/5 mm was ~ 97.3%. These results
confirmed the feasibility of the quality assurance system for electromagnetic
field therapy.
Heehun Sung, Jaehyeon Seo, Geon Oh, Yongha Gi, Hyunwoo Kim & Myonggeun Yoon
Department of Bioengineering, Korea
University, Seoul, Republic of Korea
Jong Hyun Kim & Myonggeun Yoon
FieldCure Ltd, Seoul, Republic of Korea
Yunhui Jo
Institute of Global Health Technology,
Korea University, Seoul, Republic of Korea
J.
Korean Phys. Soc. 81, 1029–1038 (2022). |
| |
| Technical note: Evaluation of methods for reducing edge curr…Background: Tumor-treating fields
(TTFields) therapy is increasingly utilized clinically because of its demonstrated efficacy in cancer treatment. However, the risk of skin burns must still be
reduced to improve patient safety and posttreatment quality of life.
Purpose: The purpose of this study was
to evaluate the methods of constructing electrode arrays that reduce current
density exceeding threshold values, which can cause skin burns during
TTFields therapy.
Methods: Electrode and body models were
generated using COMSOL software. The body model had the dielectric properties of the scalp. The average current density beneath the central
region of the electrode was maintained at ∼31 mA/cm2 RMS. The deviations in
current density at the edges of the electrode were reduced by three methods:adjustment
of the ceramic thickness ratio of the center to the edge from 1/5 to
4/5, adjustment of the radius of the metal plate from 5.0 to 8.0 mm, and insertion
of an insulator of width 0.5 to 2 mm at the edge.
Results: While using a single circular
electrode, adjustment of the ceramic thickness ratio, adjustment of the metal
plate radius, and insertion of an insulator near the edge reduced the deviations of
current density by 14.6%, 67.7%, and 75.3%, respectively. Similarly,
while using circular electrode arrays, inserting an insulator at the edge of each
electrode reduced the deviations of current density significantly, from 8.62 to 2.40
mA/cm2.
Conclusions: Insertion of an insulator
at the edge of each electrode was found to be the most effective method of
attaining uniform current density distribution beneath the electrode, thereby lowering
the risk of adverse effects of TTFields therapy.
Heehun Sung Geon Oh, Yongha Gi, Jaehyeon Seo
Department of Bioengineering, Korea University, Seoul,Republic of Korea
Yunhui Jo
Institute of Global Health Technology (IGHT), Korea University, Seoul,Republic of Korea
Hyunwoo Kim, Sangmin Park, Myonggeun
Yoon
Department of Bioengineering, Korea University, Seoul,Republic of Korea
FieldCure Ltd, Seoul,Republic
of Korea
Med Phys. 2022;49:4837–4844. |
| |
| Development of a dosimetry system for therapeutic X-rays usi…Purpose: To evaluate the dosimetric characteristics and applications of a
dosimetry system composed of a flexible amorphous silicon thin-film solar cell
and scintillator screen (STFSC-SS) for therapeutic X-rays.
Methods: The real-time dosimetry system was composed of a flexible a Si thin-film solar cell (0.2-mm thick), a scintillator screen to increase its efficiency, and an electrometer to measure the generated charge. The dosimetric
characteristics of the developed system were evaluated including its energy
dependence, dose linearity, and angular dependence. Calibration factors for the
signal measured by the system and absorbed dose-to-water were obtained
by setting reference conditions. The application and correction accuracy of
the developed system were evaluated by comparing the absorbed dose-to water measured using a patient treatment beam with that measured using
the ion chamber.
Results: The responses of STFSC-SS to energy, field size, depth, and sourceto-surface distance (SSD) were more dependent on measurement conditions than were the responses of the ion chamber, although the former
dependence was due to the scintillator screen, not the solar cell. The signals of STFSC-SS were also dependent on dose rate, while the responses
of solar cell alone and scintillator screen were not dependent on dose
rate. The scintillator screen reduced the output of solar cell at 6 and 15
MV by 0.60 and 0.55%, respectively. The different absorbed dose-to-water
measured using STFSC-SS for patient treatment beam differed by 0.4%
compared to those measured using the ionization chamber. The uncertainties of the developed system for 6 and 15 MV photon beams were 1.8
and 1.7%, respectively, confirming the accuracy and applicability of this
system.
Conclusions: The thin-film solar cell-based detector developed in this study
can accurately measure absorbed dose-to-water. The increased signal resulting from the use of the scintillator screen is advantageous for measuring low doses and stable signal output. In addition, this system is flexible,
making it applicable to curved surfaces, such as a patient’s body, and is
cost-effective.
Seonghoon Jeong, Wonjoong Cheon, Dongho Shin, Young Kyung Lim, Jonghwi Jeong, Haksoo Kim, Se Byeong Lee
Proton Therapy Center, National Cancer
Center, Goyang, Korea
Myonggeun Yoon
Department of Bioconvergence Engineering,
Korea University, Seoul, Korea
Med Phys. 2022;49:4768–4779 |
|
|
| The combination of tumor treating fields and hyperthermia ha…Glioblastoma multiforme (GBM), the most
common type of brain tumor, is a very aggressive and treatment-refractory
cancer, with a 5-year survival rate of approximately 5%. Hyperthermia (HT) and
tumor treating fields (TTF) therapy have been used to treat cancer, either
alone or in combination with other treatment methods. Both treatments have been
reported to increase the efficacy of other treatment techniques and to improve
patient prognosis. The present study evaluated the therapeutic effects of
combining HT and TTF on GBM cell lines. Cells were subjected to HT, TTF,
HT+TTF, or neither treatment, followed by comparisons of cell proliferation,
apoptosis, migration and invasiveness. Clonogenic assays showed that the two
treatments had a synergistic effect. The levels of cleaved PARP and cleaved
caspase-3 were higher and apoptosis was increased in cells treated with HT+TTF
than in cells treated with HT or TTF alone. In addition, HT+TTF showed greater
inhibition of GBM cell migration and invasiveness and greater downregulation of
STAT3 than either HT or TTF alone. The stronger anticancer effect of HT+TTF
suggested that this combination treatment can increase the survival rate of
patients with difficult-to-treat cancers such as GBM.
Yunhui Jo, Young In Han
Institute of Global Health Technology (IGHT), Korea University, Seoul, Republic of Korea
Eunjun Lee, Geon Oh, Heehun Sung, Yongha Gi, Hyunwoo Kim, Sangmin Park
Department of Biomedical Engineering, Korea University, Seoul, Republic of Korea
Jaehyeon Seo
Department of Bioconvergence Engineering, Korea University, Seoul, Republic of Korea
Myonggeun Yoon
Department of Biomedical Engineering, Korea University, Seoul, Republic of Korea
Department of Bioconvergence Engineering, Korea University, Seoul, Republic of Korea
Am J
Cancer Res. 2022; 12(3): 1423–1432. |
| |
| Inter fractional entrance dose monitoring as quality assuran…Introduction: This study describes a simple method of inter‑fractional photon beam monitoring to measure the entrance dose of
radiation treatment using Gafchromic EBT3 film.
Materials and Methods: The film was placed at the center of a 1‑cm thick phantom shaped like a block tray and fixed on the
accessory tray of the gantry. The entrance dose was measured following the placement of the film in the accessory tray. The
dose distribution calculated with the treatment planning system was compared with the dose distribution on the irradiated EBT3
films. The effectiveness of this methodology, as determined by gamma passing rates, was evaluated for the 22 fields of eight
three‑dimensional conformal radiotherapy (3D‑CRT) plans and the 41 fields of nine intensity‑modulated radiotherapy (RT) plans.
The plans for three‑dimensional conformal RT included treatments of the rectum, liver, breast, and head and neck, whereas the
plans for intensity‑modulated RT included treatments of the liver, brain, and lung.
Results: The gamma passing rates for 3D‑CRT ranged from 96.4% to 99.5%, with the mean gamma passing rate for 22 fields
being 98.0%. The gamma passing rate for intensity‑modulated RT ranged from 96.1% to 98.9%, with the mean gamma passing
rate for 41 fields being 97.7%. All gamma indices were over the 95% tolerance level.
Conclusions: The methodology described in this study, based on Gafchromic EBT3 film, can be utilized for inter‑fractional entrance
dose monitoring as quality assurance during RT. Clinical application of this method to patients can verify the accuracy of beam
delivery in the treatment room.
Sun Young
Moon
Department of Bio‑convergence Engineering, Korea University, Seoul
Proton Therapy Center, National Cancer Center, Goyang, Korea
Yunhui Jo,
Jaehyeon Seo, Myonggeun Yoon
Department of Bio‑convergence Engineering, Korea University, Seoul
Dongho Shin,
Proton Therapy
Center, National
Cancer Center,
Goyang, Korea
Journal of Cancer Research and Therapeutics - Volume 18 - Issue 4 - July-September 2022: 1152-1158 |
| |
| Thymidine decreases the DNA damage and apoptosis caused by t…Background
Tumor-treating fields (TTFields) is an
emerging non-invasive cancer-treatment modality using alternating electric
fields with low intensities and an intermediate range of frequency. TTFields
affects an extensive range of charged and polarizable cellular factors known to
be involved in cell division. However, it causes side-effects, such as DNA
damage and apoptosis, in healthy cells.
Objective
To investigate whether thymidine can have
an effect on the DNA damage and apoptosis, we arrested the cell cycle of human
glioblastoma cells (U373) at G1/S phase by using thymidine and then exposed
these cells to TTFields.
Methods
Cancer cell lines and normal cell (HaCaT)
were arrested by thymidine double block method. Cells were seeded into the gap
of between the insulated wires. The exposed in alternative electric fields at
120 kHz, 1.2 V/cm. They were counted the cell numbers and analyzed for cancer
malignant such as colony formation, Annexin V/PI staining, γH2AX and RT-PCR.
Results
The colony-forming ability and DNA damage
of the control cells without thymidine treatment were significantly decreased,
and the expression levels of BRCA1, PCNA, CDC25C, and MAD2 were distinctly
increased. Interestingly, however, cells treated with thymidine did not change
the colony formation, apoptosis, DNA damage, or gene expression pattern.
Conclusions
These results demonstrated that thymidine can
inhibit the TTFields-caused DNA damage and apoptosis, suggesting that combining
TTFields and conventional treatments, such as chemotherapy, may enhance
prognosis and decrease side effects compared with those of TTFields or
conventional treatments alone.
Hyesun Jeong, Sunghoi Hong
School of Biosystems and Biomedical
Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of
Korea
Hyesun Jeong, Sunghoi Hong
Department of Public Health Science,
Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
Yunhui Jo, Myonggeun Yoon
Department of Bio- Convergence
Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic
of Korea
Genes
Genom 43, 995–1001 (2021)
|
| |
| A new real-time personal dosimeter with position monitoring …Personal
dosimeters are used to measure the amount of radiation exposure in individual
radiation workers. We aimed to replace existing personal dosimeters and
evaluate a real-time scintillator-based dosimeter by monitoring its radiation
dose and checking the location exposed to radiation in the workspace. The
developed dosimeter measured the radiation dose based on a scintillating fiber
(SF) bundle, and comprised a silicon photomultiplier (SiPM), ultra-wide-band
(UWB)-based location detecting system, and Bluetooth system. The SF bundle was
exposed to radiation-emitted light, and the photons were amplified and
converted to electrical signals through the SiPM. These signals were
transferred to the user through the Bluetooth system and monitored. To evaluate
the feasibility of this mechanism as a dosimeter, we performed characteristic
tests, such as dose linearity, dependence on dose rate, energy, exposed angle,
and location coordinate mapping. Also, the dose distribution formed in circles
around the iso-center was measured to confirm the feasibility of monitoring the
exposure dose and location and to enable the radiation worker to move freely in
a workspace. We confirmed dose linearity, independence from energy and angle,
and accuracy of location monitoring in our device. The user’s locations were
measured with a difference of − 6 cm and − 4.8 cm on the x- and the y-axes, respectively. The
measured doses on our developed dosimeter were 62.7, 32.3, 21.0, and 15.4 mSv
at distances of 50, 100, 150, and 200 cm from the iso-center. In other words,
all measured doses at several points showed an error within 5% as compared to
doses provided by the conventional pocket dosimeter. These results show that
the developed SF-based dosimeter is advantageous in monitoring the exposure
dose and location in real time, and has significant potential as a new personal
dosimeter for radiation
workers.
Sun Young Moon, Myonggeun Yoon
Department of Bio-Convergence
Engineering, Korea University, Seoul, South Korea
Sun-Young Kim, Dongho Shin
Proton Therapy Center, National Cancer
Center, Goyang, South Korea
J.
Korean Phys. Soc. 78, 1133–1140 (2021). |
|
|
| Utility of fast non-local means (FNLM) filter for detection …Purpose: This study was
aimed to evaluate the utility based on imaging quality of the fast non-local
means (FNLM) filter in diagnosing lung nodules in pediatric chest computed
tomography (CT).
Methods:
We retrospectively reviewed the chest CT reconstructed with both filtered back
projection (FBP) and iterative reconstruction (IR) in pediatric patients with
metastatic lung nodules. After applying FNLM filter with six h values (0.0001,
0.001, 0.01, 0.1, 1, and 10) to the FBP images, eight sets of images including
FBP, IR, and FNLM were analyzed. The image quality of the lung nodules was
evaluated objectively for coefficient of variation (COV), contrast to noise
ratio (CNR), and point spread function (PSF), and subjectively for noise,
sharpness, artifacts, and diagnostic acceptability.
Results:
The COV was lowest in IR images and decreased according to increasing h values
and highest with FBP images (P < 0.001). The CNR was highest with IR images,
increased according to increasing h values and lowest with FBP images (P <
0.001). The PSF was lower only in FNLM filter with h value of 0.0001 or 0.001
than in IR images (P < 0.001). In subjective analysis, only images of FNLM
filter with h value of 0.0001 or 0.001 rarely showed unacceptable quality and
had comparable results with IR images. There were less artifacts in FNLM images
with h value of 0.0001 compared with IR images (p < 0.001).
Conclusion:
FNLM filter with h values of 0.0001 allows comparable image quality with less
artifacts compared
Jina Shim, Myonggeun Yoon*
Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea
Department of Diagnostic Radiology, Severance Hospital, Seoul, Republic of Korea
Mi-Jung Lee*
Department of Radiology and Research Institute of Radiological Science, Severance Children’s Hospital, Yonsei University, College of Medicine, Seoul, Republic of Korea
Youngjin Lee
Department of Radiological Science, Gachon
University, Incheon, Republic of Korea
Physica
Medica 81 (2021) 52-89
|
| |
| Sensitivity of radio-photoluminescence glass dosimeters to a…Background
This study investigated the effect of accumulated doses on radio-photoluminescence glass
dosimeters (RPLGDs) from measurements involving mega-voltage photons.
Methods
Forty-five commercially available RPLGDs were irradiated to estimate their dose responses.
Photon beams of 6, 10, and 15 MV were irradiated onto the RPLGDs inside a phantom,
which were divided into five groups with different doses and energies. Groups 1 and 2 were
irradiated at 1, 5, 10, 50, and 100 Gy in a sequential manner; Group 3 was irradiated 10
times with a dose of 10 Gy; and Groups 4 and 5 followed the same method as that of Group
3, but with doses of 50 Gy and 100 Gy, respectively. Each device was subjected to a measurement reading procedure each time irradiation.
Results
For the annealed Group 1, RPLGD exhibited a linearity response with variance within 5%.
For the non-annealed Group 2, readings demonstrated hyperlinearity at 6 MV and 10 MV,
and linearity at 15 MV. Following the 100 Gy irradiation, the readings for Group 2 were 118.7
± 1.9%, 112.2 ± 2.7%, and 101.5 ± 2.3% at 6, 10, and 15 MV, respectively. For Groups 3, 4,
and 5, the responsiveness of the RPLGDs gradually decreased as the number of repeated
irradiations increased. The percentage readings for the 10th beam irradiation with respect to
the readings for the primary beam irradiation were 84.6 ± 1.9%, 87.5 ± 2.4%, and 93.0 ±
3.0% at 6 MV, 10 MV, and 15 MV, respectively.
Conclusions
The non-annealed RPLGD response to dose was hyperlinear for the 6 MV and 10 MV photon beams but not for the 15 MV photon beam. Additionally, the annealed RPLGD exhibited a fading phenomenon when the measurement was repeated several times and demonstrated a relatively large fading effect at low energies than at high energies.
Dong Wook Kim, Han-Back Shin, Min-Joo Kim, Yu-Yun Noh, Hojae Kim, Min Cheol Han, Jihun Kim, Su Chul Han, Kyung Hwan Chang, Hojin Kim, Kwangwoo Park, Jinsung Kim
Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul,
Korea
Jiwon Sung, Jaeman Son
Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
Myonggeun Yoon
Department
of Bio-Convergence Engineering, Korea University, Seoul, Korea
Dongho Shin
Proton Therapy Center, National Cancer
Center, Goyang, Korea
PLOS ONE | https://doi.org/10.1371/journal.pone.0234829 December 3, 2020 |
| |
| Tumor treating fields (TTF) treatment enhances radiation-ind…Purpose:Tumor
treating fields (TTF) therapy is a noninvasive method that uses alternating
electric fields to treat various types of cancer. This study demonstrates the
combined effect of TTF and radiotherapy (RT) in vitro on pancreatic cancer,
which is known to be difficult to treat.
Materials and methods: In CFPAC-I and HPAF-II pancreatic cancer cell lines, the
combined in vitro effect of TTF and RT was evaluated by measuring cell counts,
markers of apoptosis, and clonogenic
cell survival. The
synergy effects were verified using
the Valeriote and Carpentier equations.
Results: TTF and RT
inhibited cancer cell growth more effectively than did mono therapy with TTF or
RT. The combined treatment also enhanced apoptosis more than mono therapy, as
shown by as says for cleaved poly (ADP-ribose) polymerase (PARP) and annexin V.
In addition, on the survival curve, this treatment method has been shown to work
synergistically.
Conclusion:These results suggest that combined treatment with
TTF and RT may be a good alter-native treatment for patients with pancreatic
cancer
Yunhui Jo
Department of Bio-convergence
Engineering, Korea University, Seoul, Korea
Geon Oh, Yongha Gi, Heehun Sung, Myonggeun
Yoon
Department of Bio-medical Engineering,
Korea University,Seoul, Korea
Eun Bin Joo, Suk Lee
Department of Radiation Oncology,
College of Medicine, Korea University, Seoul, Korea
INTERNATIONAL
JOURNAL OF RADIATION BIOLOGY2020, VOL. 96, NO. 12, 1528–1533 |
| |
| Clinical application of a gantry-attachable plastic scintill…Purpose: The entrance beam fluence of therapeutic proton scanning
beams can be monitored using a gantry-attachable plastic scintillating plate
(GAPSP). This study evaluated the clinical application of the GAPSP using
amethod that measures intensity modulated proton therapy (IMPT) beams for
patient treatment.
Methods: IMPT beams for the treatment of nine patients, at sites
that included the spine, head and neck, pelvis, and lung, were measured using
the GAPSP, composed of an EJ-212 plastic scintillator and a CMOS camera. All energy
layers distinguished by the GAPSP were accumulated to determine the dose
distribution of the treatment field. The evaluated fields were compared with
reference dose maps verified by quality assurance.
Results: Comparison of dose distributions of evaluation treatment
fields with reference dose distributions showed that the 3%/1 mm average gamma
passing rate was 96.4%, independent of the treatment site, energy range and
field size. When dose distributions were evaluated using the same criteria for
each energy layer, the average gamma passing rate was 91.7%.
Conclusions: The GAPSP is a suitable, low-cost
method for monitoring pencil beam scanning proton therapy, especially for
non-spot scanning or additional collimation. The GAPSP can also estimate the
treatment beam by the energy layer, a feature not common to other proton
dosimetry tool.
Seonghoon Jeong
Proton Therapy
Center, National Cancer Center, Goyang, Republic of Korea
Myonggeun Yoon⁎ , Jaehyeon Seo
Department of
Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea
Kwangzoo Chung,⁎ , Sung Hwan Ahn , Boram Lee, Department of Radiation
Oncology, Samsung Medical Center, Seoul, Republic of Korea
Physica
Medica 77(2020)181-186 |
|
|
| Feasibility Study of Beam Angle Optimization for Proton Trea…This
study describes a method that uses a genetic algorithm to select optimal beam
angles in proton therapy and evaluates the effectiveness of the proposed
algorithm in actual patients. In the use of the genetic algorithm to select the
optimal angle, a gene represents the angle of each field and a chromosome
represents the combination of beam angles. The fitness of the genetic
algorithm, which represents the suitability of the chromosome to the solution,
was quantified by using the dose distribution. The weighting factors of the
organs used for fitness were obtained from clinical data through logistic
regression, reflecting the dose characteristics of actual patients. Genetic
operations, such as selection, crossover, mutation, and replacement, were used
to modify the population and were repeated until an evaluation based on fitness
reached the termination criterion. The proposed genetic algorithm was tested by
assessing its ability to select optimal beam angles in three patients with
liver cancer. The optimal results for fitness, planning target volume (PTV),
normal liver, and skin in the population were compared with the clinical
treatment plans, a process that took an average of 36.8 minutes. The
dose-volume histograms (DVHs) and the fitness of the genetic algorithm plans
did not differ significantly from the actual treatment plans. These findings
indicate that the proposed genetic algorithm can automatically generate proton
treatment plans with the same quality as actual clinical treatment plans.
Jaehyeon Seo, Yunhui Jo, Sunyoung Moon and
Myonggeun Yoon∗
Department of Bio-convergence Engineering,
Korea University, Seoul 02841, Korea
Sung Hwan Ahn, Boram Lee and Kwangzoo
Chung†
Department of Radiation Oncology, Samsung
Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
Seonghoon Jeong Department of Proton Therapy Center, National
Cancer Center, Goyang 10408, Korea
Journal
of the Korean Physical Society, Vol. 77, No. 4, August 2020, pp. 312∼316 |
| |
| Evaluating direct and indirect effects of low-energy electro…Monte
Carlo simulations can classify DNA damage into different types and predict the
amount of energy deposited. Geant4-DNA was used to predict simple and complex
DNA damage induced by irradiation of low-energy electrons at 0.1–50 keV. The
number of molecules generated at different energy levels of radiation was
analyzed after observing the gradual changes in the level of water radiolysis.
ADNA model was used to categorize direct damage according to the location of
strand breaks at the atomic level. The parameters of energy threshold (minimum
amount of energy needed to break DNA strands) and 10 base pairs (maximum
distance that separates two strand breaks) were set. All instances of water
radiolysis including the main OH radical occurred most frequently at 1 keV
followed by at 1.5 and 0.5 keV. Direct strand breaks most commonly occurred at
0.5 keV followed by at 0.3 keV. Finally, most of strand breaks occurred
more frequently at 0.5 keV than at 0.3 keV. The computational measure-ment
results for indirect and direct effects of irradiation depend on the type of
simulation code and the DNA model used. Values used in Geant4 (physics list,
chemical interaction time and energy threshold)may also influence the results.
Eunae Choi and Myong Geun Yoon
Department
of Bio Convergence Engineering, Korea University, Seongbuk-gu, Republic of
Korea
Kwon
Su Chon
Catholic University of Daegu, Gyeongsan, Republic
of Korea
RADIATION
EFFECTS & DEFECTS IN SOLIDS2020, VOL. 175, NOS. 11–12, 1042–1051 |
| |
Total 41
HOME > Research