• 한국의학물리학회지:의학물리
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• 제2권2호
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• pp.109-120
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• 1991

골수이식을 받게 될 환자의 이상 골수를 완전히 죽이기 위해 MV 정도의 선질의 광자선에 의한 전신방사선요법이 시행되고 있다. 국소방사선요법에 이용되고 있는 방사선치료장치에 의한 일상적인 방법으로 환자의 전선에 걸쳐 방사선을 조사하기에는 조사면의 크기가 훨씬 미치지 못한다. 그래서 환자의 전선에 걸쳐 방사선을 조사할 수 있는 방법이 개발되어야 한다. 방사선 전신조사를 위한 여건이 병원에 따라 다를 것이기 때문에 병원에 따라 독특한 방법이 개발될 수 있다. 서울대학교병원에서는 코발트치료기 만이 두부를 기울일 수 있어서 전신조사에 이용될 수 있다. 코발트치료기의 두부를 밖으로 90$^{\circ}$ 기울일 때 선축은 수평이고 또한 맞은편 벽과 직각이 된다. 이 때 선원에서 맞은편 벽가지 거리는 319cm 이였다. 벽에서 환자의 중앙시상면까지 간격을 40cm라고 가정할 때, 중앙시상면에서 명목상 최대 조사면 크기가 122cm$\times$122em 이였고, 조사선량 분포를 측정한 결과로는 130cm$\times$129cm 이였으며 상하방향에서는 대칭이 아니였다. 환자가 쭈그리고 앉은 자세를 취한다면 조사면의 크기는 전신조사를 시행할 수 있을 정도로 충분히 크다. 환자 좌우폭의 평균을 30cm 라고 가정하고, 중앙시상면에서 선원쪽 15cm 위치에 기준표면 (SSD는 264cm, 명목상 조사면 크기 115.5cm$\times$155.5cm)을 두고 단면의 크기가 25cm$\times$25cm이고 두께가 30cm 인 폴리스티렌 팬톰에서 평판형 전리함으로 PDD를 측정하였다. 최대선량점의 깊이는 0.3cm 이였고 표면선량율은 82%, 50% 깊이는 16.9cm였다. 대향조사시 선축상 선량분포는 중점의 선량에서 10%이내로 일치하였다. SCD를 279cm. 최대 조사면, 기준깊이 15cm 에 대한 TPR 을 폴리스티렌 팬톰에서 깊이 10cm 에서 20cm 에 걸쳐 측정하였다 . 측정범위에서 TPR 은 직선성을 보였다. 인체팬톰의 최대 전단면(coronal plane) 에 있는 각 구멍에 TLD 조각을 넣고, 코발트 선원에서 팬톰의 시상면까지 거리를 279cm 되게 하고 선축은 팬톰의 27번 절편과 28번 절편의 접변과 최대 전단면의 교차선과 일치시켜 양방향에서 15분씩 조사하여 전단면에서 선량을 측정하였다. 팬톰내 선축상 중앙점의 선량을 기준으로 다른 부위의 선량을 비교하였다. 두경부와 복부, 폐의 하반에서 선량의 차이는 $\pm$ 10% 이내였고, 폐의 상반과 어깨와 골반 부위에서 선량은 10%이상 저선량을 보였다. 특히 어깨부위에는 30%이상 저선량을 보였다. 이로부터 서울대병원과 유사한 조건에서 코발트로 전신조사하는 경우에는 폐나 두경부에 대응하는 조직보상체를 이용하기보다는 어깨부위에 선량을 추가하는 것이 바람직할 것이라고 생각한다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권17호
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• pp.7897-7903
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• 2015

Background: To explored the value of 3D C-arm CT (CACT) guidance system in performing radiofrequency ablation (RFA) following transarterial chemoembolizationon (TACE) for hepatocellular carcinomas. Materials and Methods: RFA of hepatocellular carcinomas (HCC) were performed on 15 patients (21 lesions) with the assistance of CACT guidance system. Technical success, procedure time, complications and patient radiation exposure were investigated. The puncture performance level was evaluated on a five-point scale (5-1: excellent-poor). Complete ablation rate was evaluated after two months follow-up using enhanced CT scans. Results: The technical success rate of RFA procedure under CACT navigation system was 100 %. Mean total procedure time was $24.24{\pm}6.53min$, resulting in a mean effective exposure dose of $15.4{\pm}5.1mSv$. The mean puncture performance level rated for CACT guided RFA procedure was $4.87{\pm}0.35$. Complete ablation (CA) was achieved in 20 (95.2%) of the treated 21 tumors after the first RFA session. None of patients developed intra-procedural complications. Conclusions: 3D CACT guidance system enables reliable and efficient needle positioning by providing real-time intraoperative guidance for performing RFA on HCCs.

• 대한방사선기술학회지:방사선기술과학
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• 제33권4호
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• pp.327-334
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• 2010

전리방사선의 피폭에 의한 암 유발확률은 소아가 성인에 비해 크기 때문에 소아 X선 검사 시의 환자선량을 정확히 파악하는 일은 중요하다. 그러나 우리나라는 소아 환자선량에 대한 연구가 활발하지 않다. 그러므로 본 연구에서는 7세 미만 소아를 대상으로 전리함을 이용하여 흉부검사 시의 입사피부선량(entrance skin dose, ESD)을 측정하여 나이, 키, 체중, 가슴두께와 ESD의 관계를 비교한 결과는 다음과 같았다. 소아는 나이에 따라서 키, 체중 및 가슴두께가 비슷한 양상으로 증가하므로, 흉부촬영 시 측정하기 힘든 가슴두께 대신에 나이에 따라서 촬영조건을 설정해도 무방함을 알 수 있었다. 2세 미만 소아의 흉부 A-P 검사 시, kVp는 A병원에서 더 높았으나, mAs는 반대로 B병원에서 높아, ESD 값이 B병원에서 약 1.7배 높았다. 그러나 4세 이상 소아의 흉부 P-A 검사 시에는 mAs는 같았고 kVp는 B 병원에서 7 kVp 높았으나, ESD값은 FID가 먼 B병원(180 cm)에서보다 더 가까운 A병원(130 cm)에서 1.4배 정도 높았다. 또한 같은 나이라도 A-P가 P-A보다 ESD값이 높았다. 나이별에 따른 ESD값을 보면, 1세 미만은 $154{\mu}Gy$, 1세에서 4세 미만은 $194{\mu}Gy$, 4세에서 7세 미만은 $138{\mu}Gy$으로 나타났다. 이 값은 일본의 JART의 권고량($200{\mu}Gy$)보다 낮으나, EC(유럽위원회)나 영국의 NRPB의 권고량보다 높으며, 2009년 12월에 식품의약품안전평가원에 제출된 용역보고서의 진단참고준위(5세 소아에서의 중간값이 $100{\mu}Gy$)보다 높다. 결론적으로 ESD는 X선장치 시스템의 차이보다는 방사선사의 경험적 실행에 의한 촬영조건의 차이에 의해서 크게 달라짐을 알 수 있었으며, 또한 나이가 많다고 더 많은 선량을 받는 것은 아니다. 따라서 나이에 따른 소아의 적정 참고준위의 확립과 점진적인 환자선량의 저감화가 반드시 필요하다.

• 대한디지털의료영상학회논문지
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• 제14권2호
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• pp.9-14
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• 2012

Exposed dose of young child should be managed necessarily. Young child is more sensitive than adult of a Radioactivity, especially, and lives longer than adult. Must reduce exposed dose which follows The ALARA(As Low As Reasonably Achievable)rule is recommended by ICRP(International Commission on Radiological Protection)within diagnostic useful range. Therefore, We have to prepare Pediatric DRL(Diagnostic Reference Level) in Korea as soon as possible. Consequently, in this study, wish to estimate organ dose and effective dose using PCXMC Program(a PC-Based Monte Carlo Program), and measure ESD(Entrance surface dose)and organ dose using Glass dosimeter, and then compare with DRL which follows EC(European Commission)and NRPB(National Radiological Protection Board). Using glass dosimeter and PCXMC programs conforming to the International Committee for Radioactivity Prevention(ICRP)-103 tissue weighting factor based on the item before the organs contained in the Chest, Skull, Pelvis, Abdomen in the organ doses and effective dose and dose measurements were evaluated convenience. In a straightforward way to RANDO phantom inserted glass dosimeter(GD352M)by using the hospital pediatric protocol, and in a indirect way was PCXMC the program through a virtual simulation of organ doses and effective dose were calculated. The ESD in Chest PA is 0.076mGy which is slightly higher than the DRL of NRPB(UK) is 0.07mGy, and is lower than the DRL of EC(Europe) which is 0.1mGy. The ESD in Chest Lateral is 0.130mGy which is lower than the DRL of EC(Europe) is 0.2mGy. The ESD in Skull PA is 0.423mGy which is 40 percent lower than the DRL of NRPB(UK) is 1.1mGy and is 28 percent lower than the DRL of EC(Europe) is 1.5mGy. The ESD in Skull Lateral is 0.478mGy which is half than the DRL of NRPB(UK) is 0.8mGy, is 40 percent lower than the DRL of EC(Europe) is 1mGy. The ESD in Pelvis AP is 0.293mGy which is half than the DRL of NRPB(UK) is 0.60mGy, is 30 percent lower than the DRL of EC(Europe)is 0.9mGy. Finally, the ESD in Abdomen AP is 0.223mGy which is half than the DRL of NRPB(UK) is 0.5mGy, and is 20 percent lower than the DRL of EC is 1.0mGy. The six kind of diagnostic radiological examination is generally lower than the DRL of NRPB(UK)and EC(Europe) except for Chest PA. Shouldn't overlook the age, body, other factors. Radiological technician must realize organ dose, effective dose, ESD when examining young child in hospital. That's why young child is more sensitive than adult of a Radioactivity.

• Nutrition Research and Practice
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• 제12권1호
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• pp.41-46
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• 2018

BACKGROUND/OBJECTIVES: Exposure of the normal lung tissue around the cancerous tumor during radiotherapy causes serious side effects such as pneumonitis and pulmonary fibrosis. Radioprotectors used during cancer radiotherapy could protect the patient from side effects induced by radiation injury of the normal tissue. Delphinidin has strong antioxidant properties, and it works as the driving force of a radioprotective effect by scavenging radiation-induced reactive oxygen species (ROS). However, no studies have been conducted on the radioprotective effect of delphinidin against high linear energy transfer radiation. Therefore, this study was undertaken to evaluate the radioprotective effects of delphinidin on human lung cells against a proton beam. MATERIALS/METHODS: Normal human lung cells (HEL 299 cells) were used for in vitro experiments. The 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay assessed the cytotoxicity of delphinidin and cell viability. The expression of radiation induced cellular ROS was measured by the 2'-7'-dicholordihydrofluorescein diacetate assay. Superoxide dismutase activity assay and catalase activity assay were used for evaluating the activity of corresponding enzymes. In addition, radioprotective effects on DNA damage-induced cellular apoptosis were evaluated by Western blot assay. RESULTS: Experimental analysis, including cell survival assay, MTT assay, and Western blot assay, revealed the radioprotective effects of delphinidin. These include restoring the activities of antioxidant enzymes of damaged cells, increase in the levels of pro-survival protein, and decrease of pro-apoptosis proteins. The results from different experiments were compatible with each to provide a substantial conclusion. CONCLUSION: Low concentration ($2.5{\mu}M/mL$) of delphinidin administration prior to radiation exposure was radioprotective against a low dose of proton beam exposure. Hence, delphinidin is a promising shielding agent against radiation, protecting the normal tissues around a cancerous tumor, which are unintentionally exposed to low doses of radiation during proton therapy.

• 대한방사선기술학회지:방사선기술과학
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• 제39권3호
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• pp.385-390
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• 2016

방사성옥소를 이용한 2인 치료격리병실은 환자간의 불필요한 피폭선량을 유발하게 된다. 이에 본 연구에서는 방사성 옥소를 섭취 후 배설 없이 모두 인체에 분포하였다는 가정 하에 방사성 옥소의 물리적 특성 및 생물역동학적 정보를 제외한 보수적인 관점으로 몬테카를로 모의 모사를 이용한 2인 치료격리병실의 안전성을 평가하고자 한다. 실험 결과 방사성옥소에서 방출되는 364 keV의 감마선은 공기층 약 30 cm 또는 납 차폐체 3 mm가 반가층으로 작용됨을 파악할 수 있었으며, 환자간 거리 및 납 차폐체의 두께를 이용하였을 때, 입원기간(48시간)동안 상대방 환자로부터 받게 되는 외부 피폭선량은 5 mSv 이하로 법적 격리 기준선량 보다 낮게 나타남으로써 2인 치료격리병실의 효율적인 관리가 가능한 것으로 분석되었다.

• 방사선산업학회지
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• 제12권4호
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• pp.277-285
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• 2018

Patients administered radioisotope for medical purposes are regulated by each country to quarantine them until their body's radioactivity contents decrease below release criteria. To predict the quarantine period and provide it to medical staffs and patients, it is necessary to approach the assessment of the exposure dose of persons due to patients in a realistic manner. For this purpose, a whole-body effective half-life should be applied to the dose assessment equation instead of the physical half-life. In this study, we constructed a bio-kinetic model for each nuclear species based on the ICRP publication to obtain a whole-body effective half-life of 10 unsealed gamma-ray emitting nuclei from the notification of Nuclear Safety and Security Commission, and calculated the effective half-life mathematically by simulating the distribution of the radioisotope administered in the whole body as well as each organ scale. The whole-body effective half-life of $^{198}Au$, $^{67}Ga$, $^{123}I$, $^{111}In$, $^{186}Re$, $^{99m}Tc$, and $^{201}TI$ were 1,93, 2.57, 0.295, 2.805, 1.561, 0.245, and 2.397 days respectively. However, it was found to be undesirable to offer a single value of the effective half-life of $^{125}I$, $^{131}I$, and $^{169}Yb$ because the changes in the effective half-life show no linearity. A bio-kinetic model created for the internal exposure assessment has been shown to be possible to calculate the effective half-life of radioisotopes administered in the patient's body, but subsequent studies of radiolabeled compounds are required as well.

• Journal of Radiation Protection and Research
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• 제45권4호
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• pp.171-177
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• 2020

Background: This study aims to determine the effective atomic number (Zeff) from dual-energy image sets obtained using a conventional computed tomography (CT) simulator. The estimated Zeff can be used for deriving the stopping power and material decomposition of CT images, thereby improving dose calculations in radiation therapy. Materials and Methods: An electron-density phantom was scanned using Philips Brilliance CT Big Bore at 80 and 140 kVp. The estimated Zeff values were compared with those obtained using the calibration phantom by applying the Rutherford, Schneider, and Joshi methods. The fitting parameters were optimized using the nonlinear least squares regression algorithm. The fitting curve and mass attenuation data were obtained from the National Institute of Standards and Technology. The fitting parameters obtained from stopping power and material decomposition of CT images, were validated by estimating the residual errors between the reference and calculated Zeff values. Next, the calculation accuracy of Zeff was evaluated by comparing the calculated values with the reference Zeff values of insert plugs. The exposure levels of patients under additional CT scanning at 80, 120, and 140 kVp were evaluated by measuring the weighted CT dose index (CTDIw). Results and Discussion: The residual errors of the fitting parameters were lower than 2%. The best and worst Zeff values were obtained using the Schneider and Joshi methods, respectively. The maximum differences between the reference and calculated values were 11.3% (for lung during inhalation), 4.7% (for adipose tissue), and 9.8% (for lung during inhalation) when applying the Rutherford, Schneider, and Joshi methods, respectively. Under dual-energy scanning (80 and 140 kVp), the patient exposure level was approximately twice that in general single-energy scanning (120 kVp). Conclusion: Zeff was calculated from two image sets scanned by conventional single-energy CT simulator. The results obtained using three different methods were compared. The Zeff calculation based on single-energy exhibited appropriate feasibility.

• 한국의학물리학회지:의학물리
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• 제26권4호
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• pp.267-272
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• 2015

본 연구는 호흡에 따른 장기의 움직임을 고려하는 치료를 계획하는 4D CT를 촬영하는 환자에게 자동전류조절기능을 사용함에 따른 선량 및 위험도 감소를 평가하고자 하였다. 자동전류조절기능을 사용하지 않은 경우와 사용한 경우에 대하여 간암, 폐암 환자 남녀 각 10명씩에 대하여 4D CT 촬영시 조직선량, CTDI 선량, 유효선량을 CT-Expo 프로그램을 이용하여 개개 환자를 평가하였고, 방사선유발사망확률과 수명손실을 PCXMC 프로그램을 이용하여 평가하였다. 조직선량, CTDI 선량의 경우 간암, 폐암 환자의 경우 26.8%, 15.5%의 선량감소가 확인되었고, 방사선유발사망확률과 수명 손실은 간암, 폐암 환자의 경우 16.5%, 19.8%의 위험도 감소를 확인하였다. 본 연구를 통해 CT 촬영 인자를 개개 환자에 적용함으로 조직선량, 유효선량을 평가할 수 있었으며, 나이 및 성별을 고려한 위험인자를 평가할 수 있었다. 선량감소기법으로 제공되는 자동전류조절기능을 사용함으로 간암 및 폐암환자의 경우 21.2%의 선량감소와 18.2%의 위험도 감소가 있음을 확인하였다.

• 대한방사선기술학회지:방사선기술과학
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• 제23권1호
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• pp.55-61
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• 2000

This report was the results of an investigation based on the status of the mammography in the 45 medical facilities in the areas of Seoul and Kyong-Gi Do. In regard to mammography we were able to understand the rectification method of the generator, the functions, the radiographic techniques, the patient exposure dose, etc. Recently, the occurrence of breast cancer has rapidly increased and has lead to increased interest in the early discovery of breast cancer. However, mammography has not kept up with the publics interests and its demand. The main problem is thought to be a wide great difference in the quality of the facilities, especially in the techniques of radiograpic and the capabilities of the generator, which would have a major effect on the grade management of the image quality. In order to be ready and keep up with the high rate of increase of breast cancer, the standardization of mammography and the grade management is urgently required as a solution to the problems in the increase of image qualify and the decrease of dose. It is regarded that the basic guide of the techniques of photography in the mammography, which is being used in all developed countries due to the influence of the USA, should be presented, especially in Korea, and for this, more active and enthusiastic education and enlightenment should be needed.