• Title/Summary/Keyword: Canine phantom

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Evaluation Absorbed Dose During the Breast Cancer Brachytherapy in Canine Phantom (반려견 팬텀에서 유방암 근접방사선치료 시 흡수선량 평가)

  • Kim, Jung-Hoon;Lee, Deuk-Hee
    • Journal of the Korean Society of Radiology
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    • v.14 no.5
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    • pp.523-528
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    • 2020
  • The application of breast cancer, which has the highest incidence in females among cancer that is the number one cause of death for dogs, was to be evaluated the absorbed dose during brachytherapy using simulation. MCNPX program was used for simulation, and a small size canine phantom was produced to measure absorbed dose. The results of the absorbed dose was the highest at 192Ir to 1.02E-12 Gy/# for tumors, and the same tendency was shown for internal and external absorbed dose. Therefore, the selection of appropriate sources for dog breast cancer should be considered in brachytherapy, taking into account dog breeds and exposures.

Interstitial Hyperthermia by Radiofrequency Needle Electrode System : Phantom and Canine Brain Studies (8 MHz 라디오파를 이용한 자입식 온열치료 -조직등가물질을 통한 온도분포 및 개 뇌실질의 조직병리 변화에 관한 연구-)

  • Lee, Hyung-Sik;Chu, Sung-Sil;Sung, Jin-Sil;Suh, Chang-Ok;Kim, Gwi-Eon;Loh-John-Juhn-Kyu;Kim, Young-Soo;Kim, Sun-Ho;Chung, Song-Sup;Han, Eun-Kyung;Kim, Tae-Seung
    • Radiation Oncology Journal
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    • v.9 no.1
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    • pp.27-35
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    • 1991
  • An interstitial radiofrequency needle electrode system was constructed for interstitial heating of brain tissue. Radiofrequency electrodes with Thermotron RF 8 were tested in an agar phantom and in a normal canine brain to determine how variations in physical factors affected temperature distributions. Temperature distributions were checked after heating with 1 mm diameter needle electrode implants on the corners of 1 and 2 cm squares in a phantom and plot isotherms for various electrodes arrangement. We observed that the 1 cm square array would heat a volume with a 1.25 cm radius circular field cross section to therapeutic temperatures ($90\%$ relative SAR using Tm) and the 2 cm square array with a 1.75 cm radius rectangular field with central inhomogeneity. With 2 cm long electrode implants, we observed that the 1 cm square array would heat a 3 cm long sagittal section to therapeutic temperature ($90\%$ relative SAR using Tm). We found that radiofrequency electrodes could be selected to match the length of the heating area without affecting its performance. The histopathological changes associated with RF heating of normal canine brains have been correlated with thermal distributions. RF needle electrode heating was applied for 50min to generate tissue temperatures of $43^{\circ}C$. We obtained a quarter of the heated tissue material immediately after heating and sacrificed at intervals from $7\sim30$days. The acute stage (immediately after heating) was demonstrated by liquefactive necrosis, pyknosis of neuronal element in the gray matter and by some polymer-phonuclear leukocytes infiltration. The appearance of lipid-laden macrophages surrounding the area of liquefaction necrosis was demonstrated in all three sacrificed dogs. Mild gliosis occurring around the necrosis was demonstrated in the last sacrificed (Days 30) canine brain.

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Measurement and Assessment of Absolute Quantification from in Vitro Canine Brain Metabolites Using 500 MHz Proton Nuclear Magnetic Resonance Spectroscopy: Preliminary Results (개의 뇌 조직로부터 추출한 대사물질의 절대농도 측정 및 평가: 500 MHz 고자장 핵자기공명분광법을 이용한 예비연구결과)

  • Woo, Dong-Cheol;Bang, Eun-Jung;Choi, Chi-Bong;Lee, Sung-Ho;Kim, Sang-Soo;Rhim, Hyang-Shuk;Kim, Hwi-Yool;Choe, Bo-Young
    • Investigative Magnetic Resonance Imaging
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    • v.12 no.2
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    • pp.100-106
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    • 2008
  • The purpose of this study was to confirm the exactitude of in vitro nuclear magnetic resonance spectroscopy(NMRS) and to complement the defect of in vivo NMRS. It has been difficult to understand the metabolism of a cerebellum using in vivo NMRS owing to the generated inhomogeneity of magnetic fields (B0 and B1 field) by the complexity of the cerebellum structure. Thus, this study tried to more exactly analyze the metabolism of a canine cerebellum using the cell extraction and high resolution NMRS. In order to conduct the absolute metabolic quantification in a canine cerebellum, the spectrum of our phantom included in various brain metabolites (i.e., NAA, Cr, Cho, Ins, Lac, GABA, Glu, Gln, Tau and Ala) was obtained. The canine cerebellum tissue was extracted using the methanol-chloroform water extraction (M/C extraction) and one group was filtered and the other group was not under extract processing. Finally, NMRS of a phantom solution and two extract solution (90% D2O) was progressed using a 500MHz (11.4 T) NMR machine. Filtering a solution of the tissue extract increased the signal to noise ratio (SNR). The metabolic concentrations of a canine cerebellum were more close to rat’s metabolic concentration than human’s metabolic concentration. The present study demonstrates the absolute quantification technique in vitro high resolution NMRS with tissue extraction as the method to accurately measure metabolite concentration.

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Fabrication of Combined Probes for Interstitial hyperthermia and Brachyradiotherapy (고 선량율 근접 및 온열치료 병용 삽입관의 제작과 특성)

  • Chu, Sung-Sil;Kim, Sung-Kyu
    • Proceedings of the Korean Society of Medical Physics Conference
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    • 2004.11a
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    • pp.85-87
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    • 2004
  • We fabricated flexible thermoradiotherapy probes to alternated combination with Interstitial hyperthermia and Brachyradiotherapy thermoradiotherapy probe was coated by gold plate on polyethylene brachytherapy probe. When Agar phantom was heated 15 minute with 30 W radiofrequency power, temperature increased as 5oC for polyethylene probe and 20oC for gold coated polyethylene probe. We observed that the 1 cm square array would heat a volume with a 1.25 cm radius circular field cross section to therapeutic temperatures (90% relative SAR using Tm) and the 2 cm square array with a 1.75 cm radius rectangular field with central inhomogeneity. With 2 cm long electrode implants, we observed that the 1 cm square array would heat a 3 cm long sagittal section to therapeutic temperature (90% relative SAR using Tm). The histopathological changes associated with RF heating of normal canine brains have been correlated with thermal distributions. RF needle electrode heating was applied for 50 min to generate tissue temperatures of 43${\circ}$C. We obtained a quarter of the heated tissue material immediately after heating and sacrificed at intervals from 7${\sim}$30 days. The acute stage was demonstrated by liquefactive necrosis, pyknosis of neuronal element in the gray matter. Mild gliosis occurring around the necrosis was demonstrated in the last sacrificed (days30)canine brain.

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Chemical Shift Artifact Correction in MREIT

  • Minhas, Atul S.;Kim, Young-Tae;Jeong, Woo-Chul;Kim, Hyung-Joong;Lee, Soo-Yeol;Woo, Eung-Je
    • Journal of Biomedical Engineering Research
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    • v.30 no.6
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    • pp.461-468
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    • 2009
  • Magnetic resonance electrical impedance tomography (MREIT) enables us to perform high-resolution conductivity imaging of an electrically conducting object. Injecting low-frequency current through a pair of surface electrodes, we measure an induced magnetic flux density using an MRI scanner and this requires a sophisticated MR phase imaging method. Applying a conductivity image reconstruction algorithm to measured magnetic flux density data subject to multiple injection currents, we can produce multi-slice cross-sectional conductivity images. When there exists a local region of fat, the well-known chemical shift phenomenon produces misalignments of pixels in MR images. This may result in artifacts in magnetic flux density image and consequently in conductivity image. In this paper, we investigate chemical shift artifact correction in MREIT based on the well-known three-point Dixon technique. The major difference is in the fact that we must focus on the phase image in MREIT. Using three Dixon data sets, we explain how to calculate a magnetic flux density image without chemical shift artifact. We test the correction method through imaging experiments of a cheese phantom and postmortem canine head. Experimental results clearly show that the method effectively eliminates artifacts related with the chemical shift phenomenon in a reconstructed conductivity image.