방사선량의 측정, 평가에서 선량당량(dose equivalent)과 등가선량(equivalent dose)의 정의 및 차이

장시영 대한방사선 방어학회 1993 방사선방어학회지 Vol.18 No.1

국제방사선어위윈회(ICRP)는 최근의 권고 60(1990)에서 이전의 권고 26(1976)에는 없었던 새로운 용어들을 도입하였다. 이중에서도 동 위원회는 지금까지 사용되어왔던 국제방사선단위 및 측정위원회(ICRU) 개념의 "선량당량(dose equivalent)"을 대체하는 용어로 "등가선량(equivalent dose)"을 새로 정의하여 방사선방어 프로그램에의 적용을 권고하고 있다. 그러나 한편 동 위원회는 선량 당량이라는 용어도 여전히 채택하고 있기 때문에 경우에 따라 두 양의 사용시 불필요한 혼동을 불러 일으킬 수가 있다. 따라서 본 해설문에서는 방사선 방어, 관리 및 측정분야 종사자들의 이해를 돕기 위하여 두 양의 정의와 사용상의 차이점에 대하여 정리하였다. It its recent recommendation No. 60(1990), ICRP has newly introduced several terminology which had not existed in its prior recommendation No. 26(1977). Of those, a newly defined quantity “Equivalent Dose” replacing the "Dose Equivalent" of the ICRU concept has been recommended to be adopted in the radiation protection programme. However, since the committee still uses the “Dose Equivalent” and “Equivalent Dose” in its several publications, it is likely to provoke unnecessary confusions and misuses in applying these two quantities. In this paper were described the definition and difference between these two quantities to help in understanding of these two quantities among the person involved in the radiation protection activities.

Monte Carlo simulation of neutron dose equivalent by photoneutron production inside the primary barriers of a radiotherapy vault

Choi, Chang Heon,Park, So-Yeon,Park, Jong Min,Chun, Minsoo,Kim, Jung-in NUCLITAL S.R.L. GRUPPO NUCLETRON HOLDING-OLANDA 2018 PHYSICA MEDICA Vol.48 No.-

<P><B>Abstract</B></P> <P><B>Purpose</B></P> <P>To evaluate the neutron dose equivalent produced by photoneutrons inside the primary barriers of a radiotherapy vault.</P> <P><B>Methods</B></P> <P>Monte Carlo simulations were performed for investigating the production of photoneutrons as well as neutron shielding requirements. Two photon beams of 15 and 18 MV struck sheets of steel and lead, and the neutron doses were calculated at the isocenter (P<SUB>iso</SUB>) and at a distance of 50 cm from the inside wall (P<SUB>wall</SUB>) while delivering 1 Gy to the patient. The proper thicknesses of borated polyethylene (BPE) and concrete were simulated to reduce neutron contamination.</P> <P><B>Results</B></P> <P>When the primary barrier consisted of a concrete alone, the neutron doses at P<SUB>iso</SUB> were 0.5 μSv/Gy and 12.8 μSv/Gy for 15- and 18-MV, respectively. At P<SUB>wall</SUB>, the neutron doses were 15.8 μSv/Gy and 318.4 μSv/Gy for 15- and 18-MV, respectively. When 15 MV photons interacted with metal sheets, the neutron doses were 0.4–22.2 μSv/Gy at P<SUB>iso</SUB> and 15.8–812.5 μSv/Gy at P<SUB>wall</SUB>, depending on the thickness and material of the metal sheets and neutron shielding. In the case of 18 MV photons with the same configuration, the neutron doses were 0.9–59.5 μSv/Gy and 73.9–5006.1 μSv/Gy for P<SUB>iso</SUB> and P<SUB>wall</SUB>, respectively. The neutron dose delivered to the patient was reduced to the level of the dose delivered with a concrete barrier by including a 10-cm-thick BPE for each beam.</P> <P><B>Conclusions</B></P> <P>When the primary barrier shielding is designed with a metal sheet inside for high energy, proper neutron shielding should be constructed to avoid undesirable photoneutron dose.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Monte Carlo simulation for the photoneutron of photon interaction with metal. </LI> <LI> Evaluation of the neutron ambient dose equivalent by photoneutron inside bunker. </LI> <LI> Calculation of neutron dose for metal shielding material and neutron shielding. </LI> <LI> Proper laminated primary barrier design suggestion. </LI> </UL> </P>

Measurements of surgeons’ exposure to ionizing radiation dose: comparison of conventional and mini C-arm fluoroscopy

Sung, K. H.,Min, E.,Chung, C. Y.,Jo, B. C.,Park, M. S.,Lee, K. SAGE Publications 2016 The journal of hand surgery. journal of the Britis Vol.41 No.3

<P>This study was performed to measure the equivalent scattered radiation dose delivered to susceptible organs while simulating orthopaedic surgery using conventional and mini C-arm fluoroscopy. In addition, shielding effects on the thyroid, thymus, and gonad, and the direct exposure delivered to the patient's hands were also compared. A conventional and mini C-arms were installed in an operating room, and a hand and an operator phantom were used to simulate a patient's hand and a surgeon. Photoluminescence dosimeters were used to measure the equivalent dose by scattered radiation arriving at the thyroid, thymus, and gonad on a whole-body phantom in the position of the surgeon. Equivalent scattered radiation doses were measured in four groups: (1) unshielded conventional C-arm group; (2) unshielded mini C-arm group; (3) lead-shielded conventional C-arm group; and (4) lead-shielded mini C-arm group. Equivalent scattered radiation doses to the unshielded group were significantly lower in the mini C-arm group than those in the conventional C-arm group for all organs. The gonad in the lead-shielded conventional C-arm group showed the highest equivalent dose among operator-susceptible organs, and radiation dose was reduced by approximately 96% compared with that in the unshielded group. Scattered radiation was not detected in any susceptible organ in the lead-shielded mini C-arm group. The direct radiation dose to the hand phantom measured from the mini C-arm was significantly lower than that measured from the conventional C-arm. The results show that the equivalent scattered radiation dose to the surgeon's susceptible organs and the direct radiation dose to a patient's hand can be decreased significantly by using a mini C-arm rather than a conventional C-arm. However, protective lead garments, such as a thyroid shield and apron, should be applied to minimize radiation exposure to susceptible organs, even during use of mini C-arm fluoroscopy.</P>

Validation of a Model for Estimating Individual External Dose Based on Ambient Dose Equivalent and Life Patterns

Sato Rina,Yoshimura Kazuya,Sanada Yukihisa,Sato Tetsuro 대한방사선방어학회 2022 방사선방어학회지 Vol.47 No.2

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.

Effects of Newer Antipsychotic Drugs on Apomorphine-Induced Climbing Behavior in Mice

Seong Hoon Jeong,Jin Young Kim,In Won Chung 대한정신약물학회 2007 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.5 No.1

Chlorpromazine equivalence is used to chart the relative potencies of typical antipsychotic agents and is linearly related to the dopamine D2 receptor affinity. With the introduction of newer antipsychotic drugs, the roles of neurotransmitters other than dopamine have been emphasized, and it is difficult to attribute the diverse effects of these drugs to a common mechanism. Recently, several equivalent dose guidelines were published for newer antipsychotic drugs. The present study used the antagonism of apomorphine-induced climbing behavior to investigate the relationship between the clinically determined equivalent doses and behavioral effects measured using an animal model of several newer antipsychotic drugs. The antipsychotic drugs were administered 20 min before an apomorphine injection. After the apomorphine injection, climbing behavior was assessed visually for 20 min. The dose that inhibited 50% of the control group behavior was defined as the half-effective dose (HED) and was calculated from the regression line. The relationship between the HED and the published clinical minimum effective dose (MED) was investigated using linear regression analysis. All the antipsychotic drugs antagonized the apomorphine-induced climbing behavior in a dose-dependent manner. A statistically significant correlation between HED and MED was observed (Spearman’s rho=0.96, p <0.001), and a statistically significant linear relationship was also found (F =76.2, df=1, 4, p =0.001;r 2=0.950). Antipsychotics inhibit apomorphine-induced climbing behavior via D2 antagonism. Therefore, the result suggests that the common mechanism underlying the therapeutic effects of newer antipsychotics is related to dopamine D2 antagonism. However, the equivalent doses used in this study focused mainly on psychotic and behavioral symptoms, so they cannot embrace the multidimensional therapeutic effects of newer antipsychotics. Investigations of the relationship between the equivalent doses focusing on each symptom domain and the effects on diverse neurotransmitter systems would broaden our knowledge on the mechanisms of action in newer antipsychotics.

Characteristics of Movement-Induced Dose Reduction in Target Volume: A Comparison Between Photon and Proton Beam Treatment

Yoon, Myonggeun,Shin, Dongho,Kwak, Jungwon,Park, Soah,Lim, Young Kyung,Kim, Dongwook,Park, Sung Yong,Lee, Se Byeong,Shin, Kyung Hwan,Kim, Tae Hyun,Cho, Kwan Ho Elsevier 2009 Medical dosimetry Vol.34 No.3

<P><B>Abstract</B></P><P>We compared the main characteristics of movement-induced dose reduction during photon and proton beam treatment, based on an analysis of dose-volume histograms. To simulate target movement, a target contour was delineated in a scanned phantom and displaced by 3 to 20 mm. Although the dose reductions to the target in the 2 treatment systems were similar for transverse (perpendicular to beam direction) target motion, they were completely different for longitudinal (parallel to beam direction) target motion. While both modalities showed a relationship between the degree of target shift and the reduction in dose coverage, dose reduction showed a strong directional dependence in proton beam treatment. Clinical simulation of target movement for a prostate cancer patient showed that, although coverage and conformity indices for a 6-mm lateral movement of the prostate were reduced by 9% and 16%, respectively, for proton beam treatment, they were reduced by only 1% and 7%, respectively, for photon treatment. This difference was greater for a 15-mm target movement in the lateral direction, which lowered the coverage and conformity indices by 34% and 54%, respectively, for proton beam treatment, but changed little during photon treatment. In addition, we found that the equivalent uniform dose (EUD) and homogeneity index show similar characteristics during target movement. These results suggest that movement-induced dose reduction differs significantly between photon and proton beam treatment. Attention should be paid to the target margin in proton beam treatment due to the distinct characteristics of heavy ion beams.</P>

Dose Evaluation of Neutron within Containment Building of a CE type Nuclear Power Plant

Tae-Wook Kim,Jae-Mun Han,Kyung-Doek Kim,Cheol-Whan Yun,Jang-Soo Suh,Young-Jae Kim 한국방사성폐기물학회 2005 방사성폐기물학회지 Vol.3 No.1

CE형 원자력발전소를 대상으로 운전중 격납건물내 주요지점의 중성자장을 측정하여 작업자가 받을 수 있는 예상 방사선 피폭선량 등을 평가하고, 국제방사선방호위원회의 구권고(ICRP-26) 및 신권고(ICRP-60)에 따른 방사선 피폭선량 비교 및 교정 중성자장과 실제 중성자장의 방사선가중치 등을 분석해보았다. 분석결과 신권고에 따른 중성자가중치는 구권고에 의한 값보다 배 높은 것으로 나타났으며 , 측정지점의 중성자 방사선가중치 평균은 교정 중성자장의 평균과 비슷하였다. 중성자 평균에너지는 로 교정 중성자장의 평균에너지 500 keV보다 낮아 이럴 경우 각 측정지점에 대한 측정값은 실제 등가선량보다 보수적으로 평가될 수 있음을 알 수 있었다 From measured results of the neutron fields at some principal places within the containment building in a CE type nuclear power plant in operation, the radiation exposure of a worker to the neutron at there was evaluated and the equivalent dose reflecting new recommendation (ICRP 60) was compared with that doing the old one (ICRP 26). The measured neutron field was also compared with calibration neutron field. From the analysis, the following conclusion was obtained: the average neutron radiation weighting factor according to new recommendation is 2.41 to 2.71 times higher than the old one. The average neutorn radiation weighting factor at the measured place was similar to that at calibration neutron field. The average neutron energy at measured place was between 42 and 158 keV and higher than that of calibration field of 500 keV. So, the measured equivalent dose in nuclear power plant could be overestimated compared to the real equivalent dose.

Intercomparison Study of the Neutron Personnel Dosemeters

Kim,Jang-Lyul,Kim,Bong-Hwan,Chang,Si-Young 대한방사선 방어학회 1998 방사선방어학회지 Vol.23 No.1

국내 최초로 중성자 개인선량계에 대한 상호비교측정시험이 수행되었다. 기준 방사선장으로 한국원자력연구소가 보유하고 있는 중수감속 252Cf 선원을 이용하였으며, 12개 판독기관의 선량계 13종이 상호비교시험에 참가하였다. 각 참가기관으로부터 컨트롤과 예비용을 포함하여 15개의 선량계를 제출받아, 이를 2개의 조사선량군으로 나누어 4개씩 총 8개의 선량계가 실제 조사되었다. 중성자, 감아, 그리고 총 선량의 항목으로 판독기관의 보고선량을 부여된 선량으로 나누어 선량계 판독겨러과를 비교한 결과, 각각에 대하여 그 비율이 0.55∼1.34, 0.54∼1.32, 0.75∼1.20 의 분포를 갖는 것으로 나타났다. 판독기관의 자체 판독능력을 기준으로 할때 전혀 문제가 없는 것은 아니나, 현재의 상호비교시험 결과로부터 알 수 있는 것은 향후 중성자분야에 대한 개인선량계 성능시험이 시행될 경우, 판독기관들이 모두 합격범위에 둘 가능성이 높은 것으로 평가되었다. Domestic intercomparison study of the neutron personnel dosemeters was performed for the first time in Korea. Thirteen types of neutron dosemeters from twelve institutions took part in this intercomparison study and the D₂O moderated Cf-252 source of KAERI was used for irradiation. Eight of the fifteen dosemeters submitted by each participant were divided into two groups and each group was irradiated with different doses of the simulated mixed fields of neutron and gamma. The participants assessed their dosemeter reading in terms of the personal dose equivalent, Hp(10), for both neutron and gamma dose. The ratio of the reported dose equivalent to the delivered does equivalent for comparison between participants ranged from 0.55 to 1.34 for neutron, from 0.54 to 1.32 for gamma and from 0.75 to 1.20 for total dose. This intercomparison results show that all dosemeter processors, especially for neutron category, are able to pass the personnel dosemeter performance test which shall be enforced according to the ordinance of the MOST, No. 96.6.

Estimated Risk of Radiation Induced Contra Lateral Breast Cancer Following Chest Wall Irradiation by Conformal Wedge Field and Forward Intensity Modulated Radiotherapy Technique for Post-Mastectomy Breast Cancer Patients

Athiyaman, Hemalatha,M, Athiyaman,Chougule, Arun,Kumar, HS Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.12

Background: Epidemiological studies have indicated an increasing incidence of radiation induced secondary cancer (SC) in breast cancer patients after radiotherapy (RT), most commonly in the contra-lateral breast (CLB). The present study was conducted to estimate the SC risk in the CLB following 3D conformal radiotherapy techniques (3DCRT) including wedge field and forward intensity modulated radiotherapy (fIMRT) based on the organ equivalent dose (OED). Material and Methods: RT plans treating the chest wall with conformal wedge field and fIMRT plans were created for 30 breast cancer patients. The risks of radiation induced cancer were estimated for the CLB using dose-response models: a linear model, a linear-plateau model and a bell-shaped model with full dose response accounting for fractionated RT on the basis of OED. Results: The plans were found to be ranked quite differently according to the choice of model; calculations based on a linear dose response model fIMRT predict statistically significant lower risk compared to the enhanced dynamic wedge (EDW) technique (p-0.0089) and a non-significant difference between fIMRT and physical wedge (PW) techniques (p-0.054). The widely used plateau dose response model based estimation showed significantly lower SC risk associated with fIMRT technique compared to both wedge field techniques (fIMRT vs EDW p-0.013, fIMRT vs PW p-0.04). The full dose response model showed a non-significant difference between all three techniques in the view of second CLB cancer. Finally the bell shaped model predicted interestingly that PW is associated with significantly higher risk compared to both fIMRT and EDW techniques (fIMRT vs PW p-0.0003, EDW vs PW p-0.0032). Conclusion: In conclusion, the SC risk estimations of the CLB revealed that there is a clear relation between risk associated with wedge field and fIMRT technique depending on the choice of model selected for risk comparison.

Generalized equivalent uniform dose-based biological optimization in hippocampus-sparing whole-brain radiation therapy

Won Young Jin,Lee Eungman,Cho Sam Ju,Kim Kyung Su 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.12

We applied and evaluated a generalized equivalent uniform dose (gEUD)-based optimization method to hippocampus-sparing whole-brain radiation therapy (HS-WBRT) using volumetric modulated arc therapy (VMAT). Thirteen patients treated with WBRT were enrolled. To investigate the optimal value of the parameter “a” of the hippocampus for optimizing gEUD, we changed value from 1 to 40. Using the determined parameter “a” value for the hippocampus, dose-volume (DV)-based optimization and DV-based gEUD optimization (DV-gEUD) were used to generate HS-WBRT plans for 13 patients. According to the gEUD optimization, the plans for organ at risk (OAR) and the target plus OAR were denoted as DV-Upper gEUD optimization and DV-Upper+Target gEUD optimization. We analyzed and compared the dose-volume histogram (DVH) of each generated plan. The mean dosage ( Dmean) of the hippocampus was lowest when the parameter “a” of the hippocampus was 20, with acceptable compromise of the D100% and the Dmax of the hippocampus. The hippocampus D100%, Dmean, and Dmax were reduced to 1.78% (p = 0.014), 2.40% (p = 0.236), and 2.81% (p = 0.207), respectively, when the DV-Upper gEUD optimization was used compared to DV-base optimization and reduced to 4.76% (p = 0.001), 5.84% (p = 0.001), and 6.91% (p = 0.000), respectively, when using the DV-Upper+Target gEUD optimization. Comparing the DV-Upper gEUD and the Upper+Target gEUD optimization, these values were further reduced to 2.99% (p = 0.022), 3.50% (p = 0.059), and 4.18% (p = 0.049), respectively, when the Upper+Target gEUD optimization was used. The DV-gEUD optimization plan showed a better dosimetric profile compared to the DV-based optimization. For HS-WBRT treatment plans using gEUD-based optimization, we recommend that the parameter “a” of the hippocampus be set at 20 and that the gEUD of the OARs and the planning target volume (PTV) be optimized at the same time.