Earticle

Warfarin is a frequently prescribed anticoagulant in rehabilitation patients. Adverse drug reactions of warfarin were reported as bleeding and cutaneous microvascular thrombosis. Major bleeding, such as intracranial hemorrhage and psoas hematoma, in patients receiving anticoagulation therapy is a rare condition, but sometimes very serious complication that can even be fatal. Patient-specific factors (eg, age, body size, race, concurrent diseases, and medications) explain some of the individual variability in warfarin dose, but genetic factors, which influence warfarin response, explain a significantly higher proportion of the variability in the dose. There are two identified genes that are responsible for the main proportion of the genetic effect: CYP2C9, which codes for the enzyme cytochrome P450 2C9 that metabolizes S-warfarin, and VKORC1, which codes for warfarin’s target, vitamin K epoxide reductase. We report a case of intolerance to warfarin dosing, due to impaired drug metabolism in a patient with CYP2C9*1/*3 and VKORC 1173TT. Fortunately, there are no severe complications.

Background: After the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, a model was developed to estimate the external exposure doses for residents who were expected to return to their homes after evacuation orders were lifted. However, the model’s accuracy and uncertainties in parameters used to estimate external doses have not been evaluated. Materials and Methods: The model estimates effective doses based on the integrated ambient dose equivalent (H*(10)) and life patterns, considering a dose reduction factor to estimate the indoor H*(10) and a conversion factor from H*(10) to the effective dose. Because personal dose equivalent (Hp(10)) has been reported to agree well with the effective dose after the FDNPS accident, this study validates the model’s accuracy by comparing the estimated effective doses with Hp(10). The Hp(10) and life pattern data were collected for 36 adult participants who lived or worked near the FDNPS in 2019. Results and Discussion: The estimated effective doses correlated significantly with Hp(10); however, the estimated effective doses were lower than Hp(10) for indoor sites. A comparison with the measured indoor H*(10) showed that the estimated indoor H*(10) was not underestimated. However, the Hp(10) to H*(10) ratio indoors, which corresponds to the practical conversion factor from H*(10) to the effective dose, was significantly larger than the same ratio outdoors, meaning that the conversion factor of 0.6 is not appropriate for indoors due to the changes in irradiation geometry and gamma spectra. This could have led to a lower effective dose than Hp(10). Conclusion: The estimated effective doses correlated significantly with Hp(10), demonstrating the model’s applicability for effective dose estimation. However, the lower value of the effective dose indoors could be because the conversion factor did not reflect the actual environment.

본 연구는 방사선 작업종사자들의 최근 5년간의 개인피폭선량을 조사하여 연도별, 성별, 연령별로 심부선량과 표면선 량을 측정하여 방사선 피폭의 관리 상태를 분석하여 방사선에 의한 장해위험도를 알아보고 방사선 발생장치의 발전과 방사선 작업종사자들의 수적인 증가와 근무여건이 장기화 되어가는 것을 고려하여 방사선 관계종사들의 건강관리를 위한 예방차원과 방사선 피폭의 위험에 대한 피폭을 최소화 하기위하여 본 연구를 실시하였다. 2016년 1월 1일부터 2020년 12월 31일까지 한국 의료기관의 방사선 관계종사들의 방사선 개인피폭선량 측정 대상자 중 5,811명에 대한 5년간 분기별 연도별 피폭선량 자료 116,220건을 대상으로 연도별, 연령별, 성별에 따른 심부선량과 표면선량을 평균과 분기별 평균으로 나누어 분석하였다. 5년간의 평균 피폭선량에서 연도별로는 2016년부터 2020년까지 연도가 지날 때 마다 평균 심부선량과 표면선량이 낮게 관찰되었으며. 통계적으로 유의한 차이를 보였다 (p < 0.05). 성별 평균 피폭선량은 심부선량과 표면선량 모두 남자가 여자보다 평균적으로 방사선 피폭선량이 유의하게 높게 나타났음을 알 수 있었다 (p < 0.05). 연령별 평균 피폭선량은 심부선량과 표면선량에서 저 연령군이 고 연령군보다 상대적으로 높게 관찰되었으며, 통계적으로 유의한 차이를 보였다 (p < 0.05). 방사선 작업종사자의 연도별, 성별, 연령별 5년간의 피폭선 량에서는 국제방사선방어위원회 (ICRP)에서 권고하는 허용선량기준치인 20 mSv/year를 초과하지 않는 범위 내에서 피폭을 받은 것으로 나타났으며, 연도별에서는 통계적으로 유의한 차이가 나타났지만 분기별에서는 통계적으로 유의한 차이가 나타나지 않았다.

This study aimed to examine the individual doses of radiological technologists during the last 5-year period, and measure deep and shallow doses by year, gender, and age in order to analyze the management status of radiation exposure and thereby investigate the risk for disorders due to radiation. This study intended to minimize the risk of radiation exposure of radiological technologists, and contribute to the development of preventive measures for the health management of radiation workers in consideration of the development of equipment for diagnosis, the increase in the number of radiological technologists, and their long-term work in radiation-related working conditions. The analyses of average deep and shallow doses by year, age, and gender as well as average deep and shallow doses by quarter were conducted using the quarterly and yearly exposure dose data of 116,220 cases collected for 5 years from January 1, 2016 to December 31, 2020. The data used was collected from 5,811 persons among the subjects of individual exposure dose measurements among radiation workers working in medical institutions in Korea. With respect to the average exposure dose for 5 years, in the average exposure dose by year, average deep and shallow doses were decreased over time from 2016 to 2020, and there was a significant difference (p < 0.05). As for average exposure doses by gender, both average deep and shallow doses were significantly higher in males than in females (p < 0.05). As to average exposure doses by age, average deep and shallow doses were relatively higher in the older age group than in the younger age group, and there was a significant difference (p < 0.05). The exposure doses of radiological technologists by year, gender, and age during a 5-year period did not exceed 20 mSv/year, the standard dose recommended by the International Commission on Radiation Protection (ICRP). There was a statistically significant difference in individual dose between years, but there was no statistically significant difference between quarters.

연구로 1,2호기 해체과정에서 발생되는 많은 양의 철재폐기물 중 자체처분대상 철재폐기물을 대상으로 재활용하는 경우에 대해서 피폭방사선량을 평가하고, 규제해제농도기준(안)을 도출하였다. 평가도구는 RESRAD-RECYCLE ver 3.06을 이용하여 ICRP60에서 제시하고 있는 유효선량 개념에 근거한 내부피폭 선량환산인자를 수정하였고, IAEA Safety Series 111-P-1.1 및 NUREG-1640을 적용하여 예상되는 최대개인선량 및 집단선량을 평가하였다. 0.4 Bq/g의 철재폐기물에 대한 RESRAD-RECYCLE 전산코드의 평가결과 개인최대선량 및 집단선량은 23.9 Sv/y, 0.11 manSv/y이다. 최종적인 핵종별 규제해제농도기준은 일반평가방법과 세부평가결과를 종합하여 가장 보수적인 평가결과를 추출하여 결정하였다. 그 결과 , C 핵종에 대한 규제해제농도준위는 1.14 Bq/g미만이 되어야 국내 원자력법에서 정하고 있는 처분제한치(최대개인선량 : 10 Sv/y, 집단선량 : 1 manSv/y)를 만족할 수 있다.

The exposure dose form recycling of a large amount of the steel scrap from the KRR-1＆2 decommissioning activities was evaluated, and also the clearance level(draft) was derived. The maximum individual dose and collective dose were evaluated by modifying internal dose conversion factor which was based on the concept of effective dose in ICRP 60, applied to the RESRAD-RECYCLE ver 3.06 computing code, IAEA Safety Series 111-P-1.1 and NUREG-1640 as the assessment tool. The result of assessment for individual dose and collective dose is 23.9 Sv per year and 0.11 manSv per year respectively. The clearance levels were ultimately determined by extracting the most conservative value form the results of the generic assessment and specific assessment methodologies. The result of clearance level for radionuclides( , C ) is less than 1.1410 Bq/g to comply with the clearance criterion(maximum individual dose : 10 Sv per year, collective dose : 1 manSv per year) provided for Korea Atomic Energy Act and relevant regulations.s.

방사선구역내의 종사자 간 선량 비교 및 동일한 구역 내에서 임상실습에 임하는 학생들의 선량을 추가하여 비교함으로써 방사선방어의 최적화 구현에 대한 기초자료를 제공하고자 하였다. 연구 대상은 2016년 1월부터 동년 12월까지 C대학병원 방사선 관리구역에 재직 중인 방사선관계종사자 121명과 방사선작업종사자 36명, 그리고 8주간의 임상실습을 이수한 121명의 학생을 비교 대상으로 하였다. 방사선관계종사자와 작업종사자 간의 심부 및 표층 선량은 관계종사자가 각각 $.7440{\pm}1.676mSv$와 $.7753{\pm}1.730mSv$로 가장 높게 나타났으며, 통계적으로 매우 유의하였다(p<.01). 세 그룹 간에는 심부 선량의 경우 임상실습학생이 $.143{\pm}.136mSv$로 가장 높게 나타났고, 표층 선량에서도 $.1513{\pm}.139mSv$로 가장 높게 나타났으며, 작업종사자가 두 경우 모두 가장 낮았다. 그룹 간의 평균의 차이는 통계적으로 매우 유의하였다(p<.01). 결론적으로 ALARA(As Low As Reasonably Achievable)원칙에 의거 철저한 관리가 필요하며, 특히 방사선안전관리의 사각지대에 놓여 있는 임상실습 학생에 대한 체계적인 피폭선량 관리가 필요할 것으로 사료된다.

The purpose of this study was to compare radiation dose among workers in the radiation zone and to compare the doses of students in clinical practice in the same area to provide basic data on optimization of radiation protection. The subjects were 121 radiation related workers, 36 radiation workers, and 121 students who completed 8 weeks of clinical practice from Jan. 2016 to Dec. The depth and surface dose between the radiation related workers and the radiation workers were the highest with $.7440{\pm}1.676mSv$ and $.7753{\pm}1.730mSv$, respectively, and statistically significant (p<.01). Among the three groups, the depth dose was the highest at $.143{\pm}.136mSv$ for clinical practice students and the highest at surface dose of $.1513{\pm}.139mSv$. The lowest in both cases, The mean difference between the two groups was statistically significant (p<.01). In conclusion, it is necessary to manage thoroughly according to the ALARA(As Low As Reasonably Achievable) principle. Especially, it is necessary to systematically manage the dose of radiation for clinical students who are in the blind spot of radiation safety management.

목적: 분화갑상선암 환자에 대한 방사성옥소(I-131) 치료는 재발율과 사망률을 감소시키는 효과적인 치료법이지만, 치료용량을 증가시킴으로써 치료율을 향상시킬 수 있는지에 대해서는 아직 논란이 있다. 본 연구에서는 최대허용선량 치료법의 효용성을 검증하고자 하였다. 대상 및 방법: 임상적 병기가 제3, 4병기이고, 6개월 이후에 I-131 전신스캔(이하 IWBS)과 혈중 thyroglobulin (이하 Tg), anti-thyroglobulin antibody (이하 ATA), 초음파검사(이하 US) 및 F-18 FDG PET 등을 통해 치료여부를 확인할 수 있었던 58명(남:여=9:49, 평균연령 $50{\pm}11$세)의 유두상갑상선암 환자를 대상으로 하였다. 이중 11명은 제4병기, 47명은 제3병기였으며, 43명(남:여=4:39, 평균연령 $50{\pm}11$세)은 7.4 GBq 이하의 고식적인 저용량치료법으로 치료하였고, 9.25 GBq 이상의 고용량 치료를 받은 환자는 15명(남:여=5:10, 평균연령 $50{\pm}12$세)으로 고용량군에서 남자가 더 많았으나 연령의 차이는 없었다. 고용량군 환자 모두에서 추적용량의 방사성옥소(평균 $77{\pm}3MBq$)를 경구 투여한 후 혈중 방사능소실곡선을 통해 최대허용선량(maximum permissible dose, 이하 MPD)을 계산하였으며, 7명에서는 말초혈액림프구의 중기염색 체분석법에 의해 생물학적으로 MPD를 계산하였다. 14명에서는 치료용량의 방사성옥소를 투여한 후 혈중 방사능소실곡선을 통해 MPD를 계산하였다. 완전치유(complete response, 이하 CR)는 IWBS에서 병소가 없어지고, 혈중 Tg치가 1 ng/mL 이하로 감소한 경우로 정의하였으며, 부분치유(partial response, 이하 PR)는 IWBS에서 병소가 없어졌더라도 혈중 Tg, ATA치가 높거나, US 또는 PET 검사에서 병소가 남아있는 경우로 정의하였다. 치료후 IWBS에서 병소가 오히려 증가하거나 변함없는 경우는 없었다. 방사성옥소 치료에 의한 부작용은 입원기간 중 타액선이 현저하게 붓고 통증이 있거나, 구토를 심하게 하는 경우, 그리고 퇴원후 1개월째 백혈구수가 20% 이상 감소한 경우로 정의하였다. 결과: 양 군간에 연속적인 수치변화를 비교하는 경우는 paired t-test를 이용하였으며, 대상군간 치료효과와 부작용의 비교는 chi-square test를 이용하였다. p값 0.05 미만을 통계적으로 유의한 차이로 인정하였다. 고용량군 환자 모두에서 추적용량과 치료용량의 방사성옥소 투여 후 혈액의 피폭선량은 각각 $0.012{\pm}0.3Gy,\;1.66{\pm}25Gy$였으며, 방사성옥소 투여 후 혈액에 전달되는 피폭선량은 추적용량보다 치료용량에서 더 많았고(1.21: 166 rad, p<0.0001), 방사성옥소 1 mCi당 혈액에 전달되는 피폭선량은 차이가 없었다($0.58{\pm}0.1\;vs.\;0.56{\pm}0.1$ rad/37 MBq, p=0.34). 추적용량 방사성옥소 투여 후 구한 MPD는 평균 $13.3{\pm}1.9GBq\;(9.7{\sim}16GBq)$ 이였고, 치료용량 방사성옥소 투여 후 구한 MPD는 평균 $13.8{\pm}2.1GBq(10.4{\sim}16.3GBq)$로 유의한 차이가 얻었으며 (p=0.20), 두 수치간에는 유의한 상관 관계가 있었다(r=0.8, p<0.0001). 7명의 환자에서 말초혈액림프구 중기염색체 분석법으로 MPD를 측정하였는데 혈액의 피폭선량은 $1.78{\pm}0.03Gy$였으며, 같은 환자에서 혈중 방사능소실곡선으로부터 구한 피폭선량은 $1.54{\pm}0.03Gy$로 유의하게 낮았으나 (p=0.01), 두 측 정치 간에는 유의한 상관관계(r=0.86, p=0.01)가 있었다. 저용량 치료군 43명 중 22명(51.2%)에서 완전치유를 보였고 21명(48.8%)에서는 부분치유를 보인 반면, 고용량 치료군 15명 중 12명(80%)에서

Purpose: Radioiodine (I-131) therapy is an effective modality to reduce both recurrence and mortality rates in differentiated thyroid cancer. Whether higher doses shows higher therapeutic responses was still debatable. The purpose of this study was to validate curve-fitting (CF) method measuring maximum permissible dose (MPD) by a biological dosimetry using metaphase analysis of peripheral blood lymphocytes. Materials and Methods: Therapeutic effects of MPD was evaluated in 58 patients (49 females and 9 males, mean age $50{\pm}11$ years) of papillary thyroid cancer. Among them 43 patients were treated with ${\Leq}7.4GBq$, while 15 patients with ${\geq}9.25GBq$. The former was defined as low-dose group, and the latter high-dose group. Therapeutic response was defined as complete response when complete disappearance of lesions on follow-up I-131 scan and undetectable serum thyroglobulin levels were found. Statistical comparison between groups were done using chi-square test. P value less than 0.05 was regarded as statistically significant. Results: MPD measured by CF method using tracer and therapeutic doses were $13.3{\pm}1.9\;and\;13.8{\pm}2.1GBq$, respectively (p=0.20). They showed a significant correlation (r=0.8, p<0.0001). Exposed doses to blood measured by CF and biological methods were $1.54{\pm}0.03\;and\;1.78{\pm}0.03Gy$ (p=0.01). They also showed a significant correlation (r=0.86, p=0.01). High-dose group showed a significantly higher rate of complete response (12/15, 80%) as compared to the low-dose group (22/43, 51.2%) (p=0.05). While occurrence of side effects was not different between two groups (40% vs. 30.2%, p=0.46). Conclusion: Measurement of MPD using CF method is reliable, and the high-dose I-131 therapy using MPD gains significantly higher therapeutic effects as compared with low-dose therapy.