Sung Yong Park

Sungkyunkwan University, Sŏul, Seoul, South Korea

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Publications (87)162.85 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Conventional laser accelerated proton beam has broad energy spectra. It is not suitable for clinical use directly, so it is necessary for employing energy selection system. However, in the conventional laser accelerated proton system, the intensity of the proton beams in the low energy regime is higher than that in the high energy regime. Thus, to generate spread-out-Bragg peak (SOBP), stronger weighting value to the higher energy proton beams is needed and weaker weighting value to the lower energy proton beams is needed, which results in the wide range of weighting values. The purpose of this research is to investigate a method for efficient generating of the SOBP with varying magnetic field in the energy selection system using a carbon-proton mixture target. Energy spectrum of the laser accelerated proton beams was acquired using Particle-In-Cell simulations. The Geant4 Monte Carlo simulation toolkit was implemented for energy selection, particle transportation, and dosimetric property measurement. The energy selection collimator hole size of the energy selection system was changed from 1 to 5 mm in order to investigate the effect of hole size on the dosimetric properties for Bragg peak and SOBP. To generate SOBP, magnetic field in the energy selection system was changed during beam irradiation with each beam weighting factor. In this study, our results suggest that carbon-proton mixture target based laser accelerated proton beams can generate quasi-monoenergetic energy distribution and result in the efficient generation of SOBP. A further research is needed to optimize SOBP according to each range and modulated width using an optimized weighting algorithm.
    08/2014;
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    ABSTRACT: Purpose We evaluated the glass dosimeter suitability as an external audit program in proton therapy beam. A feasibility test of the glass dosimeter postal dose intercomparison was performed for high-energy proton beam use in radiation oncology with the collaboration of five proton therapy centers (Shizuoka Cancer Center, University of Florida Proton Center, MD Anderson Cancer Center, Loma Linda University Medical Center, and University of Pennsylvania School of Medicine). Material and methods The dosimetric properties of a GD-301 glass dosimeter were investigated for its potential use for postal dosimetry. Measurements were performed in a water phantom using a stair-like holder specially designed for this study. The depth-dose distribution measured with the glass dosimeter was compared to those from GEANT4 Monte-Carlo simulation. The GEANT4 code was also used to simulate the influence of holder material in the absorbed dose by inserting the glass dosimeter in a water phantom within the stair-like holder. We investigated the methodology of the absorbed dose determination with the glass dosimeter system establishing the calibration factor and various correction factors (non-linearity, fading, energy, holder). The participating proton therapy centers were asked to irradiate the glass dosimeter to 2 Gy with similar setup and conditions. Results The repeatability and dose rate dependence is within 1.2% and 1.5%, respectively. Depth-dose distributions in the pristine Bragg curve and the spread-out Bragg curve were estimated to be within 3%, compared with depth-dose measured with the ionization chamber. The difference in absorbed dose between the glass dosimeter and ionization chamber was within ±2% as a function of proton beam quality, residual ranges were between 2.1 and 9.0 cm. The influence of the holder material in absorbed doses of the proton beams is less than 1%. In the accuracy evaluation of the glass dosimeter system established in blind test, we obtained within 2.5% agreements with the ionization chamber dosimetry for the proton beam. In this feasibility study, the results on the proton beam output check are relatively good within ±6% for all participating centers. Conclusion We believe that the glass dosimeter system has considerable potential to be used for a postal dose audit program in proton beam.
    Radiation Measurements 12/2013; 59:66–72. · 0.86 Impact Factor
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    ABSTRACT: One-lung ventilation (OLV) is accomplished with a double-lumen tube (DLT) or a bronchial blocker (BB). The authors compared the effectiveness of lung collapse using DLT, BB, and BB with the disconnection technique. Prospective, randomized, blind trial. A university hospital. Fifty-two patients undergoing elective pneumothorax surgery. Patients were assigned randomly to 1 of 3 groups: The DLT group (group 1), the BB group (group 2), and the BB with the disconnection technique group (group 3). The authors modified the disconnection technique in group 3 as follows: (1) turned off the ventilator and opened the adjustable pressure-limiting valve, allowing both lungs to collapse and (2) after loss of the CO2 trace on the capnograph, inflated the blocker cuff and turned on the ventilator, allowing only dependent-lung ventilation. Five and ten minutes after OLV, the degree of lung collapse was assessed by the surgeon, who was blinded to the isolation technique. The quality of lung collapse at 5 and 10 minutes was significantly better in groups 1 and 3 than in group 2. No significant differences were observed for the degree of lung collapse at any time point between groups 1 and 3. The average time for loss of the CO2 trace on the capnograph was 32.3±7.0 seconds in group 3. A BB with spontaneous collapse took longer to deflate and did not provide equivalent surgical exposure to the DLT. The disconnection technique could be helpful to accelerate lung collapse with a BB.
    Journal of cardiothoracic and vascular anesthesia 11/2013; · 1.06 Impact Factor
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    ABSTRACT: We develop a sustainable anti-biofouling ultrafiltration membrane nanocomposites by covalently immobilizing silver nanoparticles (AgNPs) onto poly(vinylidene fluoride) (PVDF) membrane mediated by a thiol-end functional amphiphilic block copolymer linker. Field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDXS) measurements reveal that the AgNPs are highly bound and dispersed to the PVDF membrane due to the strong affinity of the AgNPs with the thiol-modified block copolymeric linkers, which have been anchored to the PVDF membrane. The membrane performs well under water permeability and particle rejection measurements, despite the high deposition of AgNPs on the surface of membrane. The Ag-PVDF membrane nanocomposite significantly inhibits the growth of bacteria on the membrane surface, resulting in enhanced anti-biofouling property. Importantly, the AgNPs are not released from the membrane surface due to the robust covalent bond between the AgNPs and the thiolated PVDF membrane. The stability of the membrane nanocomposite ensures a sustainable anti-biofouling activity of the membrane.
    ACS Applied Materials & Interfaces 10/2013; · 5.90 Impact Factor
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    ABSTRACT: The aim of this work was to study the feasibility of proton radiography (pRad) as a patient-specific range compensator (RC) quality assurance (QA) tool and to validate its clinical utility by performing QA on RCs having three kinds of possible defects. In order to achieve pRad for a single EBT film, proton beam currents were modulated with new weighting factors, maximizing the linearity of optical-density-to-thickness ratio. Two RCs, examined to be accurately manufactured as planned, were selected to estimate the feasibility of our pRad. The optical densities of the EBT film on which the RC was irradiated with the modulated proton beam were digitized to pixel values (pv) and then converted to thickness using a thickness-pv calibration curve. The thickness information on the pRad was compared with plan data that had been extracted from treatment planning system. The mean thickness difference (TD) over the flat RC regions was calculated as 0.39 mm, and the standard deviation as 0.22 mm, and the proton scattering effect was analyzed by step phantom measurement. Even proton scattering effected a TD of over 1 mm in the large gradient region, the percentage of pixels over the acceptance criterion was only within 1.11% and 3.49%, respectively, when a 1 mm distance to agreement tolerance limit was applied. The QA results for both precisely and imprecisely manufactured RCs demonstrated the high potential utility and clinical applicability of the pRad-based RC QA tool.
    Physics in Medicine and Biology 09/2013; 58(18):6511-6523. · 2.70 Impact Factor
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    ABSTRACT: PURPOSE: To evaluate the retinal thickness and volume measured with the enhanced depth imaging (EDI) method compared with those measured with the conventional method using spectral-domain optical coherence tomography (OCT). DESIGN: Retrospective, observational, case-control study. METHODS: Clinical records of 20 healthy subjects and those of 35 patients with chorioretinopathy (central serous chorioretinopathy, polypoidal choroidal vasculopathy, Vogt-Koyanagi-Harada disease, and reticular pseudodrusen) were analyzed retrospectively. All subjects underwent spectral-domain OCT using both the conventional and the EDI OCT raster scan protocols. The raster scan was composed of 31 B-scans that were 9.0 mm in length and 240 μm apart. Retinal thickness and volume of 9 Early Treatment Diabetic Retinopathy Study subfields were investigated. Intraclass correlation coefficients, Bland-Altman plots, and Wilcoxon signed-rank test results were used for the analysis. RESULTS: Sixty-five eyes of 35 patients with chorioretinal diseases and 40 eyes of 20 normal healthy subjects were evaluated. The automatically measured retinal thickness and volume of 9 Early Treatment Diabetic Retinopathy Study subfields with conventional and EDI raster scan showed an intraclass correlation coefficient of 0.861 to 0.995 and 0.873 to 0.995, respectively. The 95% limits of agreement between the 2 protocols in the measurement of central subfield were -14.52 to 12.88 μm in retinal thickness and -0.014 to 0.013 mm(3) in retinal volume. The differences of segmentation error rate between the 2 protocols were statistically insignificant (P > .05), except in eyes with reticular pseudodrusen in the subgroup analysis (P = .006). No significant differences were observed in measured values between healthy eyes and unaffected fellow eyes. CONCLUSIONS: The EDI OCT raster scan showed high agreement with conventional OCT in the measurement of retinal thickness and volume and could be used to evaluate both the retina and choroid in normal eyes and in eyes with some forms of chorioretinal disorder.
    American Journal of Ophthalmology 06/2013; · 4.02 Impact Factor
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    ABSTRACT: Ten plans for Ir 192 high-dose-rate intracavitary radiotherapy (ICR) after 30 { 40 Gy external beam radiotherapy were investigated. The ICR prescription dose for each insertion was 4 or 5 Gy to point A twice weekly and the total dose of ICR ranged from 24 to 30 Gy (median: 24). A fractional 100 % dose was prescribed to point A. Two sets of CT images, before and after packing, were acquired at the rst ICR session with artifact-free applicators in place. The International Commission on Radiation Units and Measurements Report 38 (ICRU-38) rectal and bladder points and the percentage of volumes receiving 50 %, 80 % and 100 % of the prescribed dose were analyzed and compared. Conventional point A plans were performed. The mean values of the bladder and rectal ICRU-38 point doses before packing, 109.93 % and 117.80 %, were lower after packing, 98.85 % and 94.93 %, respectively, with the dierence not being signicant (p = 0.013). The maximum point doses of the bladder and rectum were decreased by 20.12 % and 16.01 %, respectively. The mean-volume fractions of the bladder receiving 50 %, 80 % and 100 % of the reference dose were decreased by 8.29 %, 4.48 % and 2.64 % while the decrease of the mean-volume fractions for the rectum were relatively small at 4.44 %, 1.52 % and 1.20 %, respectively. However, this reduction was not signicant based on a p value of about 0.15 $ 0.81. While the dose at the reference point was decreased signicantly due to the packing eects, the presence or the absence of packing had little eect on volumetric doses because the volumes enlarged by the packing eects were relatively small compared to the volume of either the entire bladder or the rectum itself. Packing is still needed as it could reduce the complications caused by the high point dose and decrease the maximum dose. PACS numbers: 87.53.Jw, 87.53.Tf Keywords: Intravaginal packing, Intracavitary radiotherapy £ E-mail: suhsanta@catholic.ac.kr -250-Intravaginal Packing Eects of CT-Guided Intracavitary¡ ¡ ¡ { Doo-Hyun Lee et al. -251-Fig. 1. ICRU report-38 recommended reference points of the bladder and the rectum.
    Journal- Korean Physical Society 03/2013; 54:250-254. · 0.51 Impact Factor
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    ABSTRACT: 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.
    Medical Physics 02/2013; 40(2):021725. · 2.91 Impact Factor
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    ABSTRACT: The behavioral characteristics of axially loaded precast FRP-concrete composite decks have been examined through flexural tests in order to verify the applicability to cable stayed bridge. The deck of a cable stayed bridge is naturally subjected to compressive forces. However, the precast FRP-concrete composite deck exhibits a small concrete section resisting to compression. Moreover, the deck is vulnerable to compression with a reduced cross-sectional stiffness because FRP of the deck under compression is governed by a compressive elastic modulus smaller than its tensile modulus. The results of the bending test on the axially loaded deck revealed a loss of the cross-sectional stiffness of about 5–13% but without effect on the serviceability. In addition, since large compressive stress is developed in concrete due to the axial load, the contribution of the axial load should be considered during the selection of the range where the precast FRP-concrete composite deck will be applied. From this study, it is verified that the precast FRP-concrete composite deck can be used as deck system for cable stayed bridge.
    Composites Part B Engineering 01/2013; 44(1):679–685. · 2.14 Impact Factor
  • Engineering 01/2013; 05(11):856-864.
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    ABSTRACT: A new motion-based gated proton therapy for the treatment of orbital tumors using real-time eye-tracking system was designed and evaluated. 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. 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. The developed automatic eye-tracking based beam-gating system enabled us to perform high-precision proton radiotherapy of orbital tumors.
    Medical Physics 07/2012; 39(7):4265-73. · 2.91 Impact Factor
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    ABSTRACT: To evaluate the suitability of the GD-301 glass dosimeter for in vivo dose verification in proton therapy. The glass dosimeter was analyzed for its dosimetrics characteristic in proton beam. Dosimeters were calibrated in a water phantom using a stairlike holder specially designed for this study. To determine the accuracy of the glass dosimeter in proton dose measurements, we compared the glass dosimeter and thermoluminescent dosimeter (TLD) dose measurements using a cylindrical phantom. We investigated the feasibility of the glass dosimeter for the measurement of dose distributions near the superficial region for proton therapy plans with a varying separation between the target volume and the surface of 6 patients. Uniformity was within 1.5%. The dose-response has good linearity. Dose-rate, fading, and energy dependence were found to be within 3%. The beam profile measured using the glass dosimeter was in good agreement with the profile obtained from the ionization chamber. Depth-dose distributions in nonmodulated and modulated proton beams obtained with the glass dosimeter were estimated to be within 3%, which was lower than those with the ionization chamber. In the phantom study, the difference of isocenter dose between the delivery dose calculated by the treatment planning system and that measured by the glass dosimeter was within 5%. With in vivo dosimetry, the calculated surface doses overestimated measurements by 4%-16% using glass dosimeter and TLD. It is recommended that bolus be added for these clinical cases. We also believe that the glass dosimeter has considerable potential for use with in vivo patient proton dosimetry.
    International journal of radiation oncology, biology, physics 06/2012; 84(2):e251-6. · 4.59 Impact Factor
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    ABSTRACT: During beating heart surgery, the accuracy of cardiac output (CO) measurement techniques may be influenced by several factors. This study was conducted to analyze the clinical agreement among stat CO mode (SCO), continuous CO mode (CCO), arterial pressure waveform-based CO estimation (APCO), and transesophageal Doppler ultrasound technique (UCCO) according to the vessel anastomosis sites. This study was prospectively performed in 25 patients who would be undergoing elective OPCAB. Hemodynamic variables were recorded at the following time points: during left anterior descending (LAD) anastomosis at 1 min and 5 min; during obtuse marginal (OM) anastomosis at 1 min and 5 min: and during right coronary artery (RCA) anastomosis at 1 min and 5 min. The variables measured including the SCO, CCO, APCO, and UCCO. CO measurement techniques showed different correlations according to vessel anastomosis site. However, the percent error observed was higher than the value of 30% postulated by the criteria of Critchley and Critchley during all study periods for all CO measurement techniques. In the beating heart procedure, SCO, CCO and APCO showed different correlations according to the vessel anastomosis sites and did not agree with UCCO. CO values from the various measurement techniques should be interpreted with caution during OPCAB.
    Korean journal of anesthesiology 05/2012; 62(5):423-8.
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    ABSTRACT: The GD-301 radiophotoluminescent glass dosimeter system has recently become commercially available. The purpose of this study was to investigate the dosimetric characteristics (reproducibility, linearity, dose rate, fading, angular dependence, and depth-dose distribution) of this system for clinical dosimetry in a high-energy proton beam and to compare it with lithium fluoride TLD-100. The depth-dose distribution measured with the glass dosimeter was compared to those from GEANT4 Monte-Carlo simulation. All measurements were performed in a proton beam (IBA Proton Therapy System-Proteus 235) at the National Cancer Center in Korea. Dosimeters were irradiated in a water phantom using a stair-shaped holder specially designed for this study. Maximum height was 100mm with 1mm steps in each of ten-tiers. Reproducibility in the 200 MeV proton beam was within 1.5% for the glass dosimeter, and within 1.7% for TLD-chip responses. The glass dosimeter signal was linear as a function of applied dose in the range of 1-10 Gy. The dose rate dependence of both dosimeters was within 1.5%. The fading effect of the glass dosimeter was found to be within 1.6% for 6 months. Angular dependence of the glass dosimeter was measured to be approximately 1.3% for angles that were 80° from the beam axis using a cylindrical phantom. Depth-dose distributions in the non-modulated and modulated proton beams obtained with the glass dosimeter were estimated to be within 3.0% lower than those measured with the ionization chamber and simulation model using GEANT4 code. The Bragg peak depths determined from the ionization chamber, the glass dosimeter and GEANT4 simulation were 84.8mm, 84.2mm and 85.0mm, respectively. For the modulated proton beam, the SOBP width between the 90% proximal and the distal dose levels as obtained from the glass dosimeter was 48.1mm. The SOBP width measured with the ionization chamber was 52.2mm. Measurements comparing the glass dosimeter and TLD-100 dosimetric characteristics demonstrated the suitability of use of the glass dosimeter for dose measurement in high-energy proton beam therapy.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 04/2012; 70(8):1616-23. · 1.09 Impact Factor
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    ABSTRACT: There has been dosimetry using scintillator screen for proton quality assurance recently. To develop a proton beam dosimetry system using scintillator, we evaluated the dosimetric properties and imaging quality for three kinds of scintillator screens. Proton beam ranges of 6, 9, and 12 g/cm2 were determined in a water phantom using an ion chamber. Beam current was optimized about each scintillator screen at proton beam ranges of 6, 9, and 12 g/cm2. Dose rate was in beam condition of proton treatment. For comparison of the dosimetric properties, the quenching correction factors and standard deviations for the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) were obtained using the relation between the light yield (scintillator-relative output) and the dose distribution (diode-relative output). The image qualities for the scintillator screens were compared, using the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR), in consideration of the physical properties of the scintillator materials. After correction of the quenching effect, the correction factor for scintillator screen Gd2O2S:Tb was the lowest, at 0.004 g/(cm2 MeV). The standard deviations of the difference between the yields measured by the scintillator screens and the diode detector averaged 1, 1.3, and 1.3, respectively, at all of the ranges from origin to the peak position. The dosimetric properties of scintillator screens were no large difference. The SNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 28.67, 40.18, and 24.56, respectively, at all ranges. The CNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 0.44, 0.33, and 0.42, respectively, at all ranges. The highest SNR and the lowest CNR of scintillator screen Gd2O2S:Tb were more excellent than those of the other scintillator screens. We evaluated the dosimetric properties in terms of the quenching-effect correction factors, standard deviations image qualities in terms of SNR and CNR about scintillator screens. The correction factor and standard deviation for scintillator screens made no large difference. Scintillator screen Gd2O2S:Tb had the highest value of SNR and the lowest value of CNR, and accordingly was considered to be best in proton beam imaging quality.
    Japanese Journal of Applied Physics 03/2012; 51(4):6401-. · 1.07 Impact Factor
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    ABSTRACT: In this work, three-dimensional (3D) film-based proton beam measurements were used for the first time to verify the patient-specific 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.
    Radiation Protection Dosimetry 02/2012; 151(2):272-7. · 0.91 Impact Factor
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    ABSTRACT: We have estimated the secondary cancer risk (SCR) introduced by image-guided procedures during proton therapy. The physical dose from imaging radiation and the corresponding organ equivalent dose were calculated for the case of a lumbar spine patient. The maximum physical dose delivered to the patient during the imaging procedure was estimated to be ~0.35% of the prescribed dose of 46 Gy. However, this small imaging dose substantially raised the radiation-induced SCR by ~8%. In addition, the clinical benefit (improved accuracy during the procedure) and costs (extra SCR) associated with image-guided procedures were quantitatively modelled by systematically investigating the changes in SCR as a function of the prescribed dose, treatment target volume and imaging field size. The results showed that the SCR varied sensitively with the volume receiving the imaging and the therapeutic radiation, whereas the SCR depended to a lesser extent on the magnitude of the applied therapeutic radiation. These results showed that the additional SCR introduced by imaging radiation could be efficiently reduced by minimizing the imaging field size during image-guided procedures.
    Journal of Radiological Protection 11/2011; 31(4):477-87. · 1.39 Impact Factor
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    ABSTRACT: A parameter study of radiation therapy with laser-accelerated electrons using a sharp density transition scheme was performed via computer simulations. Through particle-in-cell (PIC) simulations, a study of the optimum conditions for the generation of a monoenergetic electron beam was conducted. The beam quality can be controlled by adjusting the laser focal spot size. The charge of the electron bunch is related to the area of the phase mixing region. An electron bunch with the maximum charge was produced in the maximum area of the mixing region in a specific focal spot case. The energy spread of the electron bunch increases with increasing focal spot size owing to the nonlocalized acceleration phase of the wakefield in the larger focal spot case. The transverse bunch size decreases with increasing focal spot size from the narrower transverse size of the ion cavity in the larger focal spot. The dosimetric properties of these very-high-energy electron beams were calculated using Monte Carlo simulations.
    Japanese Journal of Applied Physics 11/2011; 50(11):6201-. · 1.07 Impact Factor
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    ABSTRACT: This study examined the dose response of an optically stimulated luminescence dosemeter (OSLD) to megavoltage photon and electron beams. A nanoDot™ dosemeter was used to measure the dose response of the OSLD. Photons of 6-15 MV and electrons of 9-20 MeV were delivered by a Varian 21iX machine (Varian Medical System, Inc. Milpitas, CA, USA). The energy dependency was <1 %. For the 6-MV photons, the dose was linear until 200 cGy. The superficial dose measurements revealed photon irradiation to have an angular dependency. The nanoDot™ dosemeter has potential use as an in vivo dosimetric tool that is independent of the energy, has dose linearity and a rapid response compared with normal in vivo dosimetric tools, such as thermoluminescence detectors. However, the OSLD must be treated very carefully due to the high angular dependency of the photon beam.
    Radiation Protection Dosimetry 06/2011; 149(2):101-8. · 0.91 Impact Factor
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    ABSTRACT: We evaluated the effect of a contrast agent (CA) on proton beam range in a treatment planning system (TPS) for patients with locoregionally advanced lung cancer. Two sets of computed tomography (CT) images (with and without CA) were obtained from 20 patients with lung cancer. Because the increase in Hounsfield unit (∆HU) value of the heart and great vessels due to the effect of CA is most prominent among thoracic structures, to evaluate the effect of CA on proton beam range in the TPS, we compared the calculated distal ranges in the plan with CA-enhanced CT with those with corrected CT, in which the HU values of the heart and great vessels in the CA-enhanced CT were replaced by average HU values obtained from the unenhanced CT. The mean ∆HU value and the longest length of the heart and great vessels within the proton beam path in the field that passed through these structures were 189 ± 29 HU (range, 110-250 HU) and 7.1 ± 1.1 cm (range, 2.6-11.2 cm), respectively. The mean distal range error in the TPS because of the presence of CA was 1.0 ± 0.7 cm (range, 0.2-2.6 cm). If CA-enhanced CT images are used for radiotherapy planning using a proton beam for the treatment of lung cancer, our results suggest that the HU values of the heart and great vessels should be replaced by the average HU values of soft tissue to avoid discrepancies between planned and delivered doses.
    International journal of radiation oncology, biology, physics 04/2011; 81(4):e317-24. · 4.59 Impact Factor

Publication Stats

484 Citations
162.85 Total Impact Points

Institutions

  • 2013
    • Sungkyunkwan University
      • Department of Ophthalmology
      Sŏul, Seoul, South Korea
  • 2010–2013
    • Korea Institute of Construction Technology
      Kōyō, Gyeonggi Province, South Korea
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
  • 2005–2013
    • National Cancer Center Korea
      • Specific Organs Cancer Branch
      Kōyō, Gyeonggi Province, South Korea
  • 1997–2013
    • Seoul National University
      • • Department of Materials Science and Engineering
      • • School of Mechanical and Aerospace Engineering
      • • Center for Theoretical Physics
      Sŏul, Seoul, South Korea
  • 2012
    • Samsung Medical Center
      • Department of Radiation Oncology
      Seoul, Seoul, South Korea
    • Myongji Hospital
      Kōyō, Gyeonggi Province, South Korea
    • Ajou University
      • Department of Anesthesiology and Pain Medicine
      Seoul, Seoul, South Korea
  • 2011
    • McLaren Regional Medical Center
      Michigan City, Indiana, United States
    • Kyung Hee University Medical Center
      • Department of Radiation Oncology
      Seoul, Seoul, South Korea
  • 2002
    • Inha University
      • Department of Electronic and Electrical Engineering
      Seoul, Seoul, South Korea