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  • Original Article 2013-09-30 2013-09-30 \ 0 \ 199 \ 69

    The Effect of Breathing Biofeedback on Breathing Reproducibility and Patient's Dose in Respiration-gated Radiotherapy

    Sohyun An, Inhwan Yeo, Jaewon Jung, Hyunsuk Suh, Kyung Ja Lee, Jinho Choi, Kyu Chan Lee, Rena Lee

    Abstract
    We evaluated the effect of two kinds of breathing biofeedback technique such as audio-instruction and audio-visual biofeedback on breathing reproducibility and the CTV coverage during repeated treatment regimes in respiration-gated radiotherapy. In this study, the breathing data of nineteen lung cancer patients acquired from Medical College of Virginia (MCV) during five weeks were used. The dose evaluation algorithm was programmed in MATLAB. In the result, the CTV coverage was decreased as 30.0% due to the breathing irreproducibility for free-breathing. For audio-visual biofeedback, the CTV coverage was improved as 20.0% because patients can learn how control their breathing stably. And the audio-instruction was effective to preserve the breathing reproducibility.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 327 \ 78

    Reference Dosimetry and Calibration of Glass Dosimeters for Cs-137 Gamma-rays

    Young Min Moon, Dong Joo Rhee, Jung Ki Kim, Yeong-Rok Kang, Man Woo Lee, Heuijin Lim, Dong Hyeok Jeong

    Abstract
    In this research, the glass dosimeter was calibrated to measure the standard absorbed dose of the Cs-137 irradiator and absorbed dose in a biological sample. Absorbed dose in water for Cs-137 gamma ray was determined by the IAEA TRS-277 protocol. The PTW-TM30013 ion chamber and the PTW-TM41023 water phantom were utilized for measuring absorbed dose and the value was compared with the reading from DoseAce GD-302M glass dosimeter from Asahi Techno Glass Corporation for its calibration. The uncertainty of measurement (1Փ) of the calibrated glass dosimeter was 2.7% and this result would be applied to improve the accuracy in measurement of absorbed dose in a biological sample.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 271 \ 146

    Comparison of IMRT and VMAT Techniques in Spine Stereotactic Radiosurgery with International Spine Radiosurgery Consortium Consensus Guidelines

    Se An Oh, Min Kyu Kang, Sung Kyu Kim, Ji Woon Yea

    Abstract
    Stereotactic body radiation therapy (SBRT) is increasingly used to treat spinal metastases. To achieve the highest steep dose gradients and conformal dose distributions of target tumors, intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques are essential to spine radiosurgery. The purpose of the study was to qualitatively compare IMRT and VMAT techniques with International Spine Radiosurgery Consortium (ISRC) contoured consensus guidelines for target volume definition. Planning target volume (PTV) was categorized as TB, TBPT and TST depending on sectors involved; TB (vertebral body only), TBPT (vertebral body+ pedicle+transverse process), and TST (spinous process+transverse process). Three patients treated for spinal tumor in the cervical, thoracic, and lumbar region were selected. Each tumor was contoured by the definition from the ISRC guideline. Maximum spinal cord dose were 12.46 Gy, 12.17 Gy and 11.36 Gy for TB, TBPT and TST sites, and 11.81 Gy, 12.19 Gy and 11.99 Gy for the IMRT, RA1 and RA2 techniques, respectively. Average fall-off dose distance from 90% to 50% isodose line for TB, TBPT, and TST sites were 3.5 mm, 3.3 mm and 3.9 mm and 3.7 mm, 3.7 mm and 3.3 mm for the IMRT, RA1 and RA2 techniques, respectively. For the most complicated target TBPT sites in the cervical, thoracic and lumbar regions, the conformity index of the IMRT, RA1 and RA2 is 0.621, 0.761 and 0.817 and 0.755, 0.796 and 0.824 for rDHI. Both IMRT and VMAT techniques delivered high conformal dose distributions in spine stereotactic radiosurgery. However, if the target volume includes the vertebral body, pedicle, and transverse process, IMRT planning resulted in insufficient conformity index, compared to VMAT planning. Nevertheless, IMRT technique was more effective in reducing the maximum spinal cord dose compared to RA1 and RA2 techniques at most sites.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 673 \ 239

    Comparison of Intensity-modulated Radiation Therapy (IMRT), Uniform Scanning Proton Therapy (USPT), and Intensity-modulated Proton Therapy (IMPT) for Prostate Cancer: A Treatment Planning Study

    Kihong Son, Seungryong Cho, Jin Sung Kim, Youngyih Han, Sang Gyu Ju, Sung Hwan Ahn, Eunhyuk Shin, Jung Suk Shin, Won Park, Hongryul Pyo, Doo Ho Choi

    Abstract
    This study assessed compared photon and proton treatment techniques, such as intensity modulated radiation therapy (IMRT), uniform scanning proton therapy (USPT), and intensity modulated proton therapy (IMPT), for a total of 10 prostate cancers. All treatment plans delivered 70 Gy to 95% of the planned target volume in 28 fractions. IMRT plans had 7 fields for the step and shoot technique, while USPT and IMPT plans employed two equally weighted, parallel-opposed lateral fields to deliver the prescribed dose to the planned target. Inverse planning was then incorporated to optimize IMPT. The homogeneity index (HI) and conformity index (CI) for the target and the normal tissue complication probability (NTCP) for organ at risk (OAR) were calculated. Although the mean HI and CI for target were not significantly different for each treatment techniques, the NTCP of the rectum was 2.233, 3.326, and 1.707 for IMRT, USPT, and IMPT, respectively. The NTCP of the bladder was 0.008, 0.003, and 0.002 respectively. The NTCP values at the rectum and bladder were significantly lower using IMPT. Our study shows that using proton therapy, particularly IMPT, to treat prostate cancer could be beneficial compared to 7-field IMRT with similar target coverage. Given these results, radiotherapy using protons, particularly optimized IMPT, is a worthwhile treatment option for prostate cancer.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 183 \ 131

    A Low-Dose High-Resolution SPECT System with CdTe for Small-Animal Imaging Applications: A GATE Simulation Study

    Su-Jin Park, A Ram Yu, Yeseul Kim, Young-Jin Lee, Hee-Joung Kim

    Abstract
    Dedicated single-photon emission computed tomography (SPECT) systems based on pixelated semiconductors are being developed for studying small animal models of human disease. To clarify the possibility of using a SPECT system with CdTe for a high resolution low-dose small animal imaging, we compared the quality of reconstructed images from pixelated CdTe detector to those from a small SPECT system with NaI(Tl). The CdTe detector was 44.8×44.8 mm and the pixels were 0.35×0.35×5 mm. The intrinsic resolution of the detector was 0.35 mm, which is equal to the pixel size. GATE simulations were performed to assess the image quality of both SPECT systems. The spatial resolutions and sensitivities for both systems were evaluated using a 10 MBq 99mTc point source. The quantitative comparison with different injected dose was performed using a voxelized MOBY phantom, and the absorbed doses for each organ were evaluated. The spatial resolution of the SPECT with NaI(Tl) was about 1.54 mm FWHM, while that of the SPECT with a CdTe detector was about 1.32 mm FWHM at 30 mm. The sensitivity of NaI(Tl) based SPECT was 83 cps/MBq, while that of the CdTe detector based SPECT was 116 cps/MBq at 30 mm. The image statistics were evaluated by calculating the CNR of the image from both systems. When the injected activity for the striatum in the mouse brain was 160 Bq/voxel, the CNR of CdTe based SPECT was 2.30 while that of NaI(Tl) based SPECT was 1.85. The CNR of SPECT with CdTe was overall higher than that of the NaI(Tl) based SPECT. In addition, the absorbed dose was higher from SPECT with CdTe than those from NaI(Tl) based SPECT to acquire the same quantitative values. Our simulation results indicated that the SPECT with CdTe detector showed overall high performance compared to the SPECT with NaI(Tl). Even though the validation study is needed, the SPECT system with CdTe detector appeared to be feasible for high resolution low-dose small animal imaging.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 191 \ 70

    Development of Phantom for Evaluate the Suitability of Ir-192 HDR Source with Brachytherapy Tools

    Kyo Chul Shin, Sang Gyu Choi, Ki Hwan Kim, Kwang Jae Son, Dong Hyeok Jeong, Jeung Kee Kim

    Abstract
    Applicator of various kind of number ten kinds is used to raise from efficiency of brachytherapy to maximum. The compatibility of radiation source and applicator is very important subject for safety brachytherapy. Developed high dose rate brachytherapy source through Hanaro nuclear reactor in Korea Atomic Energy Research Institute and improve compatibility with using equipment in present. In this research, we wished to evaluate stability mechanical safety of radiation source and we developed phantom for evaluate several quality about Ir-192 sealed source that improve newly in Korea Atomic Energy Research Institute and is improved. The result for suitability of Ir-192 HDR source with brachytherapy tools that did normal operation in 2.2∼2.7 cm extent about change of equal curvature and consider change of sudden curvature that did normal operation in radius 1.5∼1.8 cm extent.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 376 \ 171

    Enhancement of the Early/Precise Diagnosis Based on the Measurement of SUVs in F-18 FDG PET/CT Whole-body Image

    Jeong-Kyu Park, Sung Kyu Kim, Ihn-Ho Cho, Eun-Jung Kong, Myeong-Hwan Park, Bok-Yeon Cho

    Abstract
    Through this research, we measure the data for several SUVs such as SUVLBM, SUVBW, and SUVBSA using volume of interest in order to enhance the diagnostic level in whole-body image for healthy examinees via F-18 FDG PET/CT. Maximum value, mean value, standard deviation, and threshold value for each SUVs are shown. The measurement of SUVs are carried out with 31 examinees who have taken whole-body examination with F-18 FDG PET/CT from July, 2012 to August, 2012. To secure the preciseness of measurement, we selected 26 healthy examinees as a subject of measurement according to diagnostic view of a nuclear-medical doctor. We see from the measurement of SUVs of PET/CT that the value of SUVBW is hightest and followed by SUVLBM and SUVBSA in turn regardless of the use of contrast media. By comparing the SUVLBM-maximum data for the group used contrast media with those for the group used no contrast media, there found a trend that the measured values increase when the contrast media are used. Among them, liver, aorta, lumbar-5, and Cerebellum exhibit significant difference (p<0.05). We conclude that our data for SUVs would be basic references in overall image interpretation, and hope that the research using VOI would be active.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 212 \ 131

    Development of Photoacoustic System for Breast Cancer Detection

    Soonhyouk Lee*, Yun-Seo Ji, Rena Lee

    Abstract
    Recently, the photoacoustic imaging system has been widely and intensively developed, and has been shown the possibility of diagnosis for early stage cancer. In this study, we developed a photoacoustic tomography imaging system with a commercial ultra sound device and a linear array probe. A tube phantom and a chicken breast phantom was made for the possibility of a system as a breast cancer detection. A moving average filter and a band pass filter with 3∼6 MHz bandwidth were developed for background noise elimination before delay-and-sum beamforming algorithm was used for image reconstruction. As a result, we showed that some signal processing procedure before beamforming was effective for the photoacoustic image reconstruction.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 212 \ 51

    The Development of Real Time Automatic Patient Position Correction System during the Radiation Therapy Based on CCD: A Feasibility Study

    Dongho Shin, Kwangzoo Chung, Meyoung Kim, Jaeman Son, Myonggeun Yoon, Young Kyung Lim, Se Byeong Lee

    Abstract
    Upon radiation treatment, it is the important factor to monitor the patient's motion during radiation irradiated, since it can determine whether the treatment is successful. Thus, we have developed the system in which the patient's motion is monitored in real time and moving treatment position can be automatically corrected during radiation irradiation. We have developed the patient's position monitoring system in which the patient's position is three dimensionally identified by using two CCD cameras which are orthogonal located around the isocenter. This system uses the image pattern matching technique using a normalized cross-correlation method. We have developed the system in which trigger signal for beam on and off is generated by quantitatively analyzing the changes in a treatment position through delivery of the images taken from CCD cameras to the computer and the motor of moving couch can be controlled. This system was able to automatically correct a patient's position with the resolution of 0.5 mm or less.
  • Original Article 2013-09-30 2013-09-30 \ 0 \ 241 \ 86

    Quantitative Evaluation of Gated Radiation Therapy Using Gamma Index Analysis

    Sun Young Ma, Ji Hoon Choi, Tae Sig Jeung, Sangwook Lim

    Abstract
    Generally, to evaluate gated radiation therapy, moving phantoms are used to simulate organ motion. Since the target moves in every direction, we need to take into account motion in each direction. This study proposes methods to evaluate gated radiation therapy using gamma index analysis and to visualize adequate gating window sizes according to motion ranges. The moving phantom was fabricated to simulate motion in the craniocaudal direction. This phantom consisted of a moving platform, the I'm MatriXX, and solid water phantoms. A 6 MV photon filed with a field size of 4×4 cm2 was delivered to the phantom using the gating system, while the phantom moved in the 1-, 2-, 3-, 4-, and 5-cm motion ranges. The gating windows were set at 40∼60%, 30∼40%, and 0∼90%, respectively. The I'm MatriXX acquired the dose distributions for each scenario and the dose distributions were compared with a 4×4 cm2 static filed. The tolerance of the gamma index was set at 3%/3 mm. The greater the gating window, the lower the pass rate, and the greater the motion range, the lower the pass rate in this study. In case treatment without gated radiation therapy for the target with motion of 2 cm, the pass rate was less than 96%. But it was greater than 99% when gated radiation therapy was used. However gated radiation therapy was used for the target with motion greater than 4 cm, the pass rate could not be greater than 97% when gating window was set as 30∼70%. But when the gating window set as 40∼60%, the pass rate was greater than 99%.
Korean Society of Medical Physics

Vol.35 No.2
2013-09-30

pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829

Frequency: Quarterly

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