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ABSTRACT: The authors assessed the radiation-induced cancer risk due to organ doses from kilovoltage (kV) cone beam computed tomography (CBCT), a verification technique in image-guided radiotherapy (IGRT). CBCTs were performed for three different treatment sites: the head and neck, chest, and pelvis. Using a glass dosimeter, primary doses versus depth were measured inside a homemade phantom, and organ doses were measured at various locations inside an anthropomorphic phantom. The excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) for cancer induction were estimated using the BEIR VII models based on dose measurement. The average primary (i.e., in-field) doses at the center of the phantom for standard imaging options were 1.9, 5.1, and 16.7 cGy for the head and neck, chest, and pelvis, respectively. The average secondary dose per scan for the pelvis measured 20-50 cm from the isocenter and ranged from 0.67-0.02 cGy, whereas the secondary dose per scan for the head and neck ranged from 0.07-0.003 cGy, indicating that CBCT for treatment of the head and neck is associated with a smaller secondary radiation dose than CBCT for treatment of the pelvis. The estimation of LAR from CBCT in IGRT indicated that the lifetime cancer risk for major organs can reach approximately 400 per 10,000 persons if 30 CBCT scans are performed to position a patient during radiation treatment of the pelvis site.
Health physics 05/2013; 104(5):499-503. · 0.92 Impact Factor
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Dong Wook Kim,
Weon Kuu Chung,
Dongoh Shin,
Seongeon Hong,
Sungho Park,
Sung-Yong Park,
Kwangzoo Chung,
Young Kyung Lim,
Dongho Shin,
Se Byeong Lee,
Hyun-Ho Lee,
Myonggeun Yoon
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ABSTRACT: Purpose: To compare the risk of secondary cancer from scattered and leakage doses following intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT) and tomotherapy (TOMO) in patients with lung cancer. METHODS: IMRT, VMAT and TOMO were planned for five lung cancer patients. Organ equivalent doses (OEDs) are estimated from the measured corresponding secondary doses during irradiation at various points 20 to 80 cm from the iso-center by using radio-photoluminescence glass dosimeter (RPLGD). RESULTS: The secondary dose per Gy from IMRT, VMAT and TOMO for lung cancer, measured 20 to 80 cm from the iso-center, are 0.02~2.03, 0.03~1.35 and 0.04~0.46 cGy, respectively. The mean values of relative OED of secondary dose of VMAT and TOMO, which is normalized by IMRT, ranged between 88.63% and 41.59% revealing 88.63% and 41.59% for thyroid, 82.33% and 41.85% for pancreas, 77.97% and 49.41% for bowel, 73.42% and 72.55% for rectum, 74.16% and 81.51% for prostate. The secondary dose and OED from TOMO became similar to those from IMRT and VMAT as the distance from the field edge increased. CONCLUSIONS: OED based estimation suggests that the secondary cancer risk from TOMO is less than or comparable to the risks from conventional IMRT and VMAT.
Radiation Oncology 03/2013; 8(1):47. · 2.32 Impact Factor
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ABSTRACT: Although the hippocampus is considered an important site of seizures in mesial temporal lobe epilepsy (mTLE), the amygdala may also have a significant role. Amygdala enlargement is occasionally found in patients with mTLE, and volumetric detection of amygdala enlargement has been documented in "image-negative" patients with TLE. However, only limited data have been reported on the clinical features, surgical outcomes, and pathological characteristics in patients with mTLE with amygdala enlargement. We recruited 12 patients who had undergone surgical treatment for refractory epilepsy with radiological evidence of amygdala enlargement, and 11 became seizure free. All patients showed homogenously increased amygdala volumes on MRI without enhancement and underwent surgical treatment for mTLE. Pathology results revealed that eight patients had focal cortical dysplasia (FCD), two had ganglioglioma, one had oligodendroglioma, and one had astrocytoma. The clinical features and MRI findings were largely indistinguishable between the patients with brain tumors and those with FCD, but the patients with brain tumors tended to be younger at the time of seizure onset. Our study shows that surgical treatment of epilepsy in patients with amygdala enlargement usually has a favorable outcome. FCD was the most frequent pathological diagnosis in these patients. However, a brain tumor should be considered in the differential diagnosis, especially in young patients, because it is often difficult to differentiate FCD from a brain tumor on radiological features.
Journal of Clinical Neuroscience 04/2012; 19(4):509-12. · 1.25 Impact Factor
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ABSTRACT: The Korean national health security system covers the entire population and all medical facilities. We aimed to estimate epilepsy prevalence, anticonvulsant utilization pattern and the cost. We identified prevalent epilepsy patients by the prescription of anticonvulsants under the diagnostic codes suggesting seizure or epilepsy from 2007 Korean National Health Insurance databases. The information of demography, residential area, the kind of medical security service reflecting economic status, anticonvulsants, and the costs was extracted. The overall prevalence of treated epilepsy patients was 2.41/1,000, and higher for men than women. The age-specific prevalence was the lowest in those in their thirties and forties. Epilepsy was more prevalent among lower-income individuals receiving medical aid. The regional prevalence was the highest in Jeju Island and lowest in Ulsan city. New anticonvulsants were more frequently used than old anticonvulsants in the younger age group. The total annual cost of epilepsy or seizure reached 0.46% of total medical expenditure and 0.27% of total expenditure on health. This is the first nationwide epidemiological report issued on epilepsy in Korea. Epilepsy prevalence in Korea is comparable to those in developed countries. Economic status and geography affect the prevalence of epilepsy.
Journal of Korean medical science 03/2012; 27(3):285-90. · 0.84 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. · 0.82 Impact Factor
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ABSTRACT: The aim of the present study was to formulate new fixed-dose combination tablets (FCTs) by coating a glimepiride (GLM) immediate-release (IR) layer on a metformin hydrochloride (MTF) extended-release (ER) core tablet using perforated film coating equipment. Composition of GLM-IR coating suspension for homogeneity was studied and application of near-infrared spectroscopy (NIR) to determine the end-point of the coating process was also investigated. The final product was administered to healthy male volunteers and its pharmacokinetic parameters were analyzed. GLM-IR coating suspension was prepared with a ratio of SLS to GLM at 0.75 for homogeneity. An inert mid-layer was introduced to prevent contact between MTF-ER core tablet and GLM-IR layer, which led to an increased release rate of GLM in pH 7.8 medium. The proportional correlation was confirmed between analytical results of GLM determined by NIRS and those by HPLC-UV. Thus, the end-point of the GLM coating process was determined by NIRS, the fast and non-destructive method. New FCTs were confirmed to be bioequivalent to the marketed product.
International journal of pharmaceutics 02/2012; 427(2):201-8. · 2.96 Impact Factor
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Gyungock Kim,
Jeong Woo Park,
In Gyoo Kim,
Sanghoon Kim,
Sanggi Kim,
Jong Moo Lee,
Gun Sik Park,
Jiho Joo,
Ki-Seok Jang,
Jin Hyuk Oh, [......],
Jong Moon Park,
Do-Won Kim,
Deog-Kyoon Jeong,
Moon-Sang Hwang,
Jeong-Kyoum Kim,
Kyu-Sang Park,
Han-Kyu Chi,
Hyun-Chang Kim, Dong-Wook Kim,
Mu Hee Cho
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ABSTRACT: We present high performance silicon photonic circuits (PICs) defined for off-chip or on-chip photonic interconnects, where PN depletion Mach-Zehnder modulators and evanescent-coupled waveguide Ge-on-Si photodetectors were monolithically integrated on an SOI wafer with CMOS-compatible process. The fabricated silicon PIC(off-chip) for off-chip optical interconnects showed operation up to 30 Gb/s. Under differential drive of low-voltage 1.2 V(pp), the integrated 1 mm-phase-shifter modulator in the PIC(off-chip) demonstrated an extinction ratio (ER) of 10.5dB for 12.5 Gb/s, an ER of 9.1dB for 20 Gb/s, and an ER of 7.2 dB for 30 Gb/s operation, without adoption of travelling-wave electrodes. The device showed the modulation efficiency of V(π)L(π) ~1.59 Vcm, and the phase-shifter loss of 3.2 dB/mm for maximum optical transmission. The Ge photodetector, which allows simpler integration process based on reduced pressure chemical vapor deposition exhibited operation over 30 Gb/s with a low dark current of 700 nA at -1V. The fabricated silicon PIC(intra-chip) for on-chip (intra-chip) photonic interconnects, where the monolithically integrated modulator and Ge photodetector were connected by a silicon waveguide on the same chip, showed on-chip data transmissions up to 20 Gb/s, indicating potential application in future silicon on-chip optical network. We also report the performance of the hybrid silicon electronic-photonic IC (EPIC), where a PIC(intra-chip) chip and 0.13μm CMOS interface IC chips were hybrid-integrated.
Optics Express 12/2011; 19(27):26936-47. · 3.59 Impact Factor
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Dong Wook Kim,
Weon Kuu Chung,
Dong Oh Shin,
Myonggeun Yoon,
Ui-Jung Hwang,
Jeong-Eun Rah,
Hojin Jeong,
Sang Yeob Lee,
Dongho Shin,
Se Byeong Lee,
Sung Yong Park
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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. · 0.82 Impact Factor
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ABSTRACT: In proton therapy, patient quality assurance (QA) requires measuring the beam range, spread-out Bragg peak (SOBP), and output factor. If these values can be predicted by using sampling measurements or previous QA data to find the correlation between beam setup parameters and measured data, efforts expended on patient QA can be reduced. Using sampling data, we predicted the range, SOBP, and output factor of the proton beam. To obtain sampling data, we measured the range, SOBP, and output factor for 14 data points at each of 24-beam range options, from 4-28 cm. Prediction conformity was evaluated by the difference between predicted and measured patient QA data. Results indicated that for 60% of patients, the values could be predicted within 3% of dose uncertainty.
Medical dosimetry: official journal of the American Association of Medical Dosimetrists 01/2011; 36(2):145-52. · 1.26 Impact Factor
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Young Kyung Lim,
Ui-Jung Hwang,
Dongho Shin, Dong Wook Kim,
Jungwon Kwak,
Myonggeun Yoon,
Doo Hyun Lee,
Se Byeong Lee,
Sang-Yeob Lee,
Sung Yong Park,
Hong Ryeol Pyo
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ABSTRACT: We wanted to evaluate the influence of bone cement on the proton range and to derive a conversion factor predicting the range shift by correcting distorted computed tomography (CT) data as a reference to determine whether the correction is needed. Two CT datasets were obtained with and without a bone cement disk placed in a water phantom. Treatment planning was performed on a set of uncorrected CT images with the bone cement disk, and the verification plan was applied to the same set of CT images with an effective CT number for the bone cement disk. The effective CT number was determined by measuring the actual proton range with the bone cement disk. The effects of CT number, thicknesses, and position of bone cement on the proton range were evaluated in the treatment planning system (TPS) to draw a conversion factor predicting the range shift by correcting the CT number of bone cement. The effective CT number of bone cement was 260 Hounsfield units (HU). The calculated proton range for native CT data was significantly shorter than the measured proton range. However, the calculated range for the corrected CT data with the effective CT number coincided exactly with the measured range. The conversion factor was 209.6 [HU · cm/mm] for bone cement and predicted the range shift by approximately correcting the CT number. We found that the heterogeneity of bone cement could cause incorrect proton ranges in treatment plans using CT images. With an effective CT number of bone cement derived from the proton range and relative stopping power, a more actual proton range could be calculated in the TPS. The conversion factor could predict the necessity for CT data correction with sufficient accuracy.
Medical dosimetry: official journal of the American Association of Medical Dosimetrists 10/2010; 36(3):299-305. · 1.26 Impact Factor
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Young Kyung Lim,
Jungwon Kwak, Dong Wook Kim,
Dongho Shin,
Myonggeun Yoon,
Soah Park,
Jin Sung Kim,
Sung Hwan Ahn,
Jungwook Shin,
Se Byeong Lee,
Sung Yong Park,
Hong Ryeol Pyo,
Dae Yong Kim,
Kwan Ho Cho
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ABSTRACT: We examined the feasibility of using fiducial markers composed of microscopic gold particles and human-compatible polymers as a means to overcome current problems with conventional macroscopic gold fiducial markers, such as dose reduction and artifact generation, in proton therapy for prostate cancer.
We examined two types of gold particle fiducial marker interactions: that with diagnostic X-rays and with a therapeutic proton beam. That is, we qualitatively and quantitatively compared the radiographic visibility of conventional gold and gold particle fiducial markers and the CT artifacts and dose reduction associated with their use.
The gold particle fiducials could be easily distinguished from high-density structures, such as the pelvic bone, in diagnostic X-rays but were nearly transparent to a proton beam. The proton dose distribution was distorted <5% by the gold particle fiducials with a 4.9% normalized gold density; this was the case even in the worst configuration (i.e., parallel alignment with a single-direction proton beam). In addition, CT artifacts were dramatically reduced for the gold particle mixture.
Mixtures of microscopic gold particles and human-compatible polymers have excellent potential as fiducial markers for proton therapy for prostate cancer. These include good radiographic visibility, low distortion of the depth-dose distribution, and few CT artifacts.
International journal of radiation oncology, biology, physics 09/2009; 74(5):1609-16. · 4.59 Impact Factor
