자궁경부암의 세기조절 방사선치료와 급성기 방사선 독성의 감소 : Minimizing Acute Radiation Toxicity with Intensity Modulated Radiation Therapy of Uterine Cervical Cancer

남지호 ; 이자영 ; 전호상 부산대학교 병원 암연구소 2014 부산대병원학술지 Vol.- No.35

전립선암의 세기조절 방사선치료와 급성기 방사선 독성의 감소 : Minimizing Acute Radiation Toxicity with Intensity Modulated Radiation Therapy of Prostate Cancer

남지호 ; 이자영 ; 전호상 부산대학교 병원 암연구소 2014 부산대병원학술지 Vol.- No.36

방사선 치료용 MV 영상장치의 공간해상도의 에너지 의존도 평가 : Energy dependency of spatial resolution of a mega-voltage imager for radiation treatments

전호상 ; 남지호 ; 이자영 부산대학교 병원 암연구소 2014 부산대병원학술지 Vol.- No.36

산란선 대 일차선비(SPR)를 이용한 MV 영상의 산란 보정을 위한 실험적 방법

전호상,박달,이자영,남지호,김원택,기용간,김동현,이주혜,김동원,Jeon, Hosang,Park, Dahl,Lee, Jayeong,Nam, Jiho,Kim, Wontaek,Ki, Yongkan,Kim, Donghyun,Lee, Ju Hye,Kim, Dongwon 한국의학물리학회 2014 의학물리 Vol.25 No.3

고에너지(MV, Mega-voltage) X선 영상은 일반적인 방사선 치료 시 조사야의 영상 검증이 가능한 유일한 방법으로 널리 사용되고 있다. 그러나 고에너지 특유의 높은 콤프턴 산란 반응 특성으로 인해 저에너지 영상에 비해 화질이 크게 낮으며, 1990년대에 디지털 MV 영상이 소개된 이후 화질을 보완하기 위한 연구들이 활발히 이루어져 왔다. 본 연구에서는 디지털 영상처리 기법을 이용하거나 산란 커널 계산을 통해 화질을 개선하는 기존의 방법 대신 측정된 산란선 대 일차 선비(SPR, Scatter to Primary Ratio)를 이용하는 새로운 방법을 제안하였다. 먼저 주어진 촬영 조건 하에서 환자를 모사하는 고체 물팬톰의 유무에 따라 각각 MV영상을 촬영하고 방사선의 투과율을 별도로 계산한 후 산란 성분이 포함된 일차선 영상과 포함되지 않은 일차선 영상을 각각 획득하였다. 이를 기반으로 산란 보정에 사용할 SPR 분포를 획득하였다. 그리고 알루미늄 막대를 이용한 line pair (LP) 팬텀 및 실제 환자 골반의 영상을 이용하여 산란 보정 효과의 검증을 수행하였다. SPR 측정 결과 팬톰 두께에 따른 SPR 분포들을 성공적으로 획득하였으며, LP 팬텀 검증 결과 영상의 산란 성분이 효과적으로 제거되어 팬톰 본래의 밀도 분포가 복원되었음을 확인하였다. 또한 환자 골반 영상 보정 결과 모든 관심영역에서 대조도가 평균 48% 증가하였다. 본 연구에서 제시한 MV 영상의 산란 보정 방법은 실제 측정 자료를 기반으로 하므로 높은 신뢰성을 가지며, 적은 시간과 비용으로도 임상 현장에서 즉각적인 도입이 가능하다. 결론적으로 본 연구는 MV 영상을 이용한 영상유도 방사선치료의 질을 높이기 위한 하나의 효과적인 방법이 될 수 있을 것으로 기대된다. In general radiotherapy, mega-voltage (MV) x-ray images are widely used as the unique method to verify radio-therapeutic fields. But, the image quality of MV images is much lower than that of kilo-voltage x-ray images due to scatter interactions. Since 1990s, studies for the scatter correction have performed with digital-based MV imaging systems. In this study, a novel method for the scatter correction is suggested using scatter to primary ratio (SPR), instead of conventional methods such as digital image processing or scatter kernel calculations. We measured two MV images with and without a solid water phantom describing a patient body with given imaging conditions, and calculated un-attenuated ratios. Then, we obtained SPR distributions for the scatter correction. For experimental validation, a line-pair (LP) phantom using several Al bars and a clinical pelvis MV image was used. As the result, scatter signals of the LP phantom image were successfully reduced so that original density distribution of the phantom was restored. Moreover, image contrast values increased after SPR correction at all ROIs of the clinical image. The mean value of increases was 48%. The SPR correction method suggested in this study has high reliability because it is based on actually measured data. Also, this method can be easily adopted in clinics without additional cost. We expected that the SPR correction can be an effective method to improve the quality of MV image guided radiotherapy.

Extraordinary radiation super-sensitivity accompanying with sorafenib combination therapy: what lies beneath?

이자영,이주혜,윤한빈,이호정,전호상,남지호 대한방사선종양학회 2017 Radiation Oncology Journal Vol.35 No.2

Primary liver tumor, especially hepatocellular carcinoma (HCC), is a common cause of cancer death worldwide. The incidence is generally higher in Asian countries than in western countries. Carcinogenesis of HCC is often associated with hepatitis viral infections. Current standard treatment of HCC is surgical resection or transplantation in patients with early stage disease. However, the patient with advanced stage disease, surgical resection is often limited. Sorafenib or other treatment modalities are not so effective as well. We report a case of unusual radiation super-sensitivity in advanced stage HCC, and review the literature.

Enhancement in the kV Portal Image Contrast Using Depth Normalization for Accurate Patient Localization

전호상,윤한빈,남지호,이자영,이주혜,박달,김원택,기용간,김동현,김호경 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.4

The X-ray imaging modality has played an important role in the daily verification of a patient's position for accurate radiation treatment (RT), especially in modern RT techniques that require highly precise patient localization. Although cone-beam computer tomography (CBCT) has already been introduced to the RT field, two-dimensional (2D) X-ray portal imagers have been more widely used than CBCT for the daily check of patient localization owing to the lower patient exposure and time consumption. However, the 2D imager practically provide a lower bone-tissue contrast than CBCT. Thus, we propose a method that enhances the image contrast of daily acquired 2D images by using just one CBCT scan during an entire RT course. This method operates on the basis of the depth normalization (DN) technique and requires no artificial data manipulation such as image post-processing filters. We implemented the algorithm for the portal images of a cylindrical phantom and three patients. From DN results, the image contrast for the phantom and the patients increased by factors of 26.3 and 13.4 on average, and their contrast-to-noise ratios were maintained at differences of 8.6% and 7.7% on average, respectively. Moreover, the DN method provided a stronger contrast enhancement at lower doses that could suppress the imaging exposure and thus improve the patient's safety. Therefore, the verification of RT patient localization is expected to be performed more eciently and accurately by using the DN method.

Imaging Responses of On-site CsI and Gd2O2S Flat-panel Detectors: Dependence on the Tube Voltage

전호상,정명진,윤승만,남지호,이자영,박달,김원택,기용간,김호경 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.1

One of the emerging issues in radiography is low-dose imaging to minimize patient’s exposure. The scintillating materials employed in most indirect flat-panel detectors show a drastic change of X-ray photon absorption efficiency around their K-edge energies that consequently affects image quality. Using various tube voltages, we investigated the imaging performance of most popular scintillators: cesium iodide (CsI) and gadolinium oxysulfide (Gd2O2S). The integrated detective quantum efficiencies (iDQE) of four detectors installed in the same hospital were evaluated according to the standardized procedure IEC 62220-1 at tube voltages of 40 − 120 kVp. The iDQE values of the Gd2O2S detectors were normalized by those of CsI detectors to exclude the effects of image postprocessing. The contrast-to-noise ratios (CNR) were also evaluated by using an anthropomorphic chest phantom. The iDQE of the CsI detector outperformed that of the Gd2O2S detector over all tube voltages. Moreover, we noted that the iDQE of the Gd2O2S detectors quickly rolled off with decreasing tube voltage under 70 kVp. The CNRs of the two scintillators were similar at 120 kVp. At 60 kVp, however, the CNR of Gd2O2S was about half that of CsI. Compared to the Gd2O2S detectors, variations in the DQE performance of the CsI detectors were relatively immune to variations in the applied tube voltages. Therefore, we claim that Gd2O2S detectors are inappropriate for use in low-tube-voltage imaging (e.g., extremities and pediatrics) with low patient exposure.

Structural Similarity Index 인자를 이용한 방사선 분할 조사간 환자 체위 변화의 자동화 검출능 평가: 초기 보고

윤한빈,전호상,이자영,이주혜,남지호,박달,김원택,기용간,김동현,Youn, Hanbean,Jeon, Hosang,Lee, Jayeong,Lee, Juhye,Nam, Jiho,Park, Dahl,Kim, Wontaek,Ki, Yongkan,Kim, Donghyun 한국의학물리학회 2015 의학물리 Vol.26 No.4

현대 방사선치료는 고선명 X선 투사영상을 이용하여 환자 및 종양의 위치를 확인하는 기술이 요구되지만, 3차원 영상 촬영을 위한 피폭량 및 영상정보의 급격한 증가는 환자에게 추가적인 부담이 될 수 있다. 본 연구에서는 영상의 구조 정보를 효과적으로 추출할 수 있는 Structural similarity (SSIM) 인자를 도입하여 매일 촬영하는 환자의 2차원 X선 영상간 차이를 자동 분석하여 환자의 위치 정확성의 검증 가능성을 제시하였다. 먼저 종양을 모사하기 위하여 구형 전산 팬텀의 크기와 위치를 변화시키면서 각각의 투사 영상을 시뮬레이션하고, SSIM 인자를 통해 영상 간 차이를 검출하여 분석하였다. 또한 12일간 매일 촬영한 방사선 치료 환자의 2차원 X선 영상들 간 차이를 동일한 방법으로 검출하였다. 그 결과 산출된 팬텀 변화에 따른 SSIM 값은 0.85~1 범위로, 관심영역(ROI)을 영상 전체가 아닌 팬텀으로 한정하였을 때는 0.006~1 범위로 나타나서 ROI 적용 시 민감도가 크게 상승하는 것을 확인하였다. 또한 임상 영상의 SSIM은 0.799~0.853 범위의 값을 나타냈으며 영상 간 차이가 SSIM 분포 상에 검출되는 것을 확인하였다. 본 연구결과는 소요 시간 및 피폭 등의 우려로 매일 사용하기 어려운 3차원 영상기법 대신 간단한 2차원 영상만을 이용하여 객관적이고 정량적인 환자 위치 정확성의 자동 평가 기법을 제공할 수 있을 것으로 기대된다. The modern radiotherapy technique which delivers a large amount of dose to patients asks to confirm the positions of patients or tumors more accurately by using X-ray projection images of high-definition. However, a rapid increase in patient's exposure and image information for CT image acquisition may be additional burden on the patient. In this study, by introducing structural similarity (SSIM) index that can effectively extract the structural information of the image, we analyze the differences between daily acquired x-ray images of a patient to verify the accuracy of patient positioning. First, for simulating a moving target, the spherical computational phantoms changing the sizes and positions were created to acquire projected images. Differences between the images were automatically detected and analyzed by extracting their SSIM values. In addition, as a clinical test, differences between daily acquired x-ray images of a patient for 12 days were detected in the same way. As a result, we confirmed that the SSIM index was changed in the range of 0.85~1 (0.006~1 when a region of interest (ROI) was applied) as the sizes or positions of the phantom changed. The SSIM was more sensitive to the change of the phantom when the ROI was limited to the phantom itself. In the clinical test, the daily change of patient positions was 0.799~0.853 in SSIM values, those well described differences among images. Therefore, we expect that SSIM index can provide an objective and quantitative technique to verify the patient position using simple x-ray images, instead of time and cost intensive three-dimensional x-ray images.

3D 프린팅 비압박 유방 팬텀 제작을 위한 복셀 기반 수치 모델에 관한 연구

윤한빈,백철하,전호상,김진성,남지호,이자영,이주혜,박달,김원택,기용간,김동현,원종훈,김호경,Youn, Hanbean,Baek, Cheol Ha,Jeon, Hosang,Kim, Jinsung,Nam, Jiho,Lee, Jayoung,Lee, Juhye,Park, Dahl,Kim, Wontaek,Ki, Yongkan,Kim, Donghyun,Won, Jong 대한의용생체공학회 2017 의공학회지 Vol.38 No.3

Physical breast phantoms would be useful for the development of a dedicated breast computed tomography (BCT) system and its optimization. While the conventional breast phantoms are available in compressed forms, which are appropriate for the mammography and digital tomosynthesis, however, the BCT requires phantoms in uncompressed forms. Although simple cylindrical plastic phantoms can be used for the development of the BCT system, they will not replace the roles of uncompressed phantoms describing breast anatomies for a better study of the BCT. In this study, we have designed a numerical voxel breast phantom accounting for the random nature of breast anatomies and applied it to the 3D printer to fabricate the uncompressed anthropomorphic breast phantom. The numerical voxel phantom mainly consists of the external skin and internal anatomies, including the ductal networks, the glandular tissues, the Cooper's ligaments, and the adipose tissues. The voxel phantom is then converted into a surface data in the STL file format by using the marching cube algorithm. Using the STL file, we obtain the skin and the glandular tissue from the 3D printer, and then assemble them. The uncompressed breast phantom is completed by filling the remaining space with oil, which mimics the adipose tissues. Since the breast phantom developed in this study is completely software-generated, we can create readily anthropomorphic phantoms accounting for diverse human breast anatomies.

Effect of Coenzyme Q10 on Radiation Nephropathy in Rats

기용간,김원택,김용호,김동현,배진숙,박달,전호상,이주혜,이자영,남지호 대한의학회 2017 Journal of Korean medical science Vol.32 No.5

The kidney is one of the most radiosensitive organs in the abdominal cavity and is the dose-limiting structure in cancer patients receiving abdominal or total body irradiation. In the present study, the effect of coenzyme Q10 (CoQ10) on radiation nephropathy was evaluated in rats. A total of 72 rats were equally randomized into 4 groups: Control, CoQ10, irradiation with 10 Gy (RT) + placebo, or RT + CoQ10. The 2 RT groups received single 10 Gy of abdominal irradiation. The 2 CoQ10 groups were supplemented daily with 1 mL of soybean oil containing 10 mg/kg of CoQ10. The RT + placebo and control groups received same dose of soybean oil. After 24 weeks, laboratory and histopathologic findings were compared. The 2 RT groups showed significant increases in blood urea nitrogen (BUN) and creatinine levels and significant pathologic changes such as glomerulosclerosis and tubulointerstitial fibrosis. CoQ10 supplementation resulted in significant reductions of BUN and creatinine levels compared with the RT + placebo group (P < 0.001 and P = 0.038, respectively). CoQ10 treatment significantly attenuated glomerular and tubular changes of irradiated kidney in semiquantitative analysis (P < 0.001 for both). Administration of CoQ10 can alleviate the radiation-induced nephropathy.