Calibration of plane parallel ionization chambers: a new service for secondary standard dosimetry laboratories?

This paper presents the results of calibration of PTW Markus and NACP ionization chambers following the procedures outlined in the TRS 381 International Atomic Energy Agency code of practice. According to this dosimetry protocol, calibration of plane parallel chambers follows 2 methods. The first method uses a high-energy electron beam and consists of comparing the plane parallel chamber with a cylindrical chamber whose N_D,air calibration factor, traceable to cobalt-60 (⁶⁰Co), is known, while the second method applies to a ⁶⁰Co gamma beam whose air kerma rate is known at the calibration point. As the second method is generally applied in Secondary Standard Dosimetry Laboratories, the consistency of calibrations free in-air and in a water phantom has been studied. A close agreement is shown between the 2 methods (the calibration factors differ by at most 0.98%). These results lead to the conclusion that either of the 2 calibration methods can be used, provided that the correction factors given by the TRS 381 code of practice are applied.     

加强放射诊断辐射剂量管理的必要性及应对策略

近年来, 我国放射诊断检查特别是CT检查的频次迅猛增加, 已经成为国民人均辐射剂量的最大人工辐射来源, 并有可能超过天然辐射源的贡献。临床诊疗活动中, 患者和受检者短时间内可能进行多项目、多频次的放射诊断成像, 所接受的累积辐射剂量较高, 甚至一天检查的剂量贡献超过50或100 mSv, 从而对其健康产生潜在风险。因此, 有必要对放射诊断辐射剂量信息进行统计分析与控制管理, 以尽可能降低过高剂量及其辐射危险的发生概率。本文对放射诊断辐射风险的国际认识、我国放射诊断设备和检查频次、放射诊断辐射剂量及其管理现状进行阐述, 并就辐射剂量的管理提出应对策略, 为进一步推进临床实践中的辐射防护提供参考。     

医用X射线诊断受检者放射防护最优化研究

对于医学诊断中病人接受的剂量，个人剂量限值不适用，但放射防护最优化却可以发挥大的作用。本课题尝试将放射防护最优化的原方法运用于医学诊断的受检者防护，以期改善我国病人防护现状。调查以四川、山东和北京为重点调查区。为了最优化分析目的，本调查中将病人剂量划分为现实剂量，正当剂量和优化主一三种类型，以便分别估计管理因素和设备因素对病人剂量的影响。     

北京市放射诊断受检者剂量调查与分析

目的 探讨北京地区放射诊断检查对成年受检者的辐射剂量水平。方法 选取北京市城区与远郊共10个区域的30家不同级别医疗机构,以1 182例X射线摄影、542例乳腺摄影和410例CT检查为研究对象,测读不同投照部位下照射野内受检者/模体所受的辐射剂量。结果 普通X射线摄影、CR摄影和DR摄影受检者剂量范围分别为0.4~24.1、0.3~13.9、0.1~15.9 mGy;乳腺受检者乳腺腺体平均剂量为0.3~5.4 mGy;CT受检者CTDI_w值为28.1~96.3 mGy、CTDI_vol值为7.0~23.4 mGy、DLP值为162.2~898.1 mGy ·cm。结论 个别放射诊断检查受检者所受辐射剂量高于国标中医疗照射指导水平值,应引起注意。     

平板DSA介入检查治疗患者的剂量调查

目的 调查平板数字减影血管造影(DSA)介入检查治疗患者的照射剂量,分析影响患者照射剂量的因素.方法 收集2009年3至6月来本院做DSA检查治疗的患者461例,手术种类包括全脑血管造影(CEA)、颅内动脉瘤弹簧圈栓塞(CAE)、肝脏动脉造影+超选化疗(SHAC)、冠状动脉造影(COA)、冠状动脉支架植入(PISI)、心脏射频消融(RFCA)、永久起搏器安装(PCPI).通过采集所有病例的剂量面积值(DAP)、累计皮肤表面人射剂量(CAK)、透视时间,采用转换因子计算有效剂量值.结果 CEA、CAE、SHAC、COA、PIST、RFCA、PCPI的有效剂量当量分别为(0.33±0.20)、(0.49±0.35)、(6.92±4.19)、(0.76±0.91)、(2.35±1.47)、(0.50±0.74)和(0.67±0.70)Sv;461例患者中超过1 Sv的达到120人次,占26%,超过10 Sv的达到10人次,均为SHAC患者.CAK分另为(0.55±0.43)、(1.34±1.11)、(0.95±0.57)、(0.32±0.31)、(0.91±0.33)、(0.16±0.22)和(0.15±0.14)Gy,CAK值超过1 Gy共为59例,占12.8%,超过2 Gy为11例,占2.4%,有2例超过3 Gy,为4.5和6.1 Gy,分别为CEA和CAE患者.结论 各项介入手术患者所受照射剂量个体差异较大.介入检查治疗患者接受的照射剂量较高,需要进行严格的监督以保证患者照射剂量得到最佳控制.

Abstract：

Objective To investigate the radiation doses for the patients undergoing interventional radiology and to analyze the dose - influencing factors.MethodsThe clinical data of 461 patients undergoing interventional radiology,including cerebral angiography ( CEA ),cerebral aneurysm embolism ( CAE ),superselective hepatic arterial chemoembolization ( SHAG ),coronary angiography ( COA ),percutaneous intracoronary stent implantation ( PIS1 ),cardiac radiofrequency catheter ablation ( RFCA ),and permanent cardiac pacemaker implantation(PCPI) were collected to observe the cumulative air kerma (CAK),dose area product (DAP),and fluoroscopy time,and effective dose was estimated using the conversion factors.Results The effective doses for CEA,CAE,SHAG,COA,PISI,RFCA,and PCPI were (0.33 ±0.20),(0.49 ±0.35),(6.92 ±4.19),(0.76 ±0.91),(2.35 ± 1.47),(0.50 ±0.74),and (0.67 ±0.70) Sv,respectively.In 126 of the 416 patients (26%),the effective doses were greater than 1 Sv,and the effective doses of 10 person-times were greater than 10 Sv,all of which were observed in the patients undergoing SHAG.The CAK values for CEA,CAE,SHAG,COA,PISI,RFCA,and PCPIwere (0.55 ±0.43),(1.34 ± 1.11),(0.95 ±0.57),(0.32 ±0.31),(0.91 ±0.33),(0.16 ±0.22),and (0.15 ±0.14) Gy,respectively.The CAK values were greater than 1 Gy in 59 of the 461 patients ( 12.8% ),greater than 2 Gy in 11 cases (2.4%) ,and greater than 3 Gy in 1 CEA cases and 1 CEA case,respectively.Conclusions There is a wide variation range in radiation dose for different procedures.As most interventional radiology procedure can result in clinically significant radiation dose to the patient,stricter dose control should be carried out.     

乳腺癌改良根治术后放疗降低患侧肺受量的剂量学研究

目的 探讨乳腺癌改良根治术后放疗(PMRT)3种照射技术靶区和患侧肺剂量分布的特点,评价其对降低患侧肺受量的作用。方法 对28例Ⅱ、Ⅲ期乳腺癌根治术后患者分别进行胸壁区2个切线适形野(半野)加锁骨上区调强放疗(3D-CRT+IMRT)、胸壁区加锁骨上区一体调强放疗(IMRT),以及胸壁区2个切线适形野(半野)加锁骨上区电子线单野放疗技术(3D-CRT+E)的计划设计,通过剂量体积直方图(DVH)评价靶区剂量以及患侧肺V₅、V₁₀、V₂₀及V45受照射体积,处方剂量为50.4 Gy(1.8 Gy × 28次)。结果 靶区适形指数(CI)3D-CRT+IMRT组(0.61±0.03)和IMRT组(0.62±0.03)之间差异无统计学意义(q=2.16, P>0.05),这两组CI均优于 3DCRT+E组[(0.44±0.02), q=20.50、 22.66,P<0.01];不均匀指数(HI) 3D-CRT+IMRT组 (1.17±0.02)和IMRT组(1.15±0.02)之间差异无统计学意义(q=1.66, P>0.05),这两组HI均优于 3DCRT+E 组[(1.24±0.04), q=3.91、5.58, P<0.01];患侧肺V₅ 、V₁₀,3D-CRT+E组(48.70%±3.24%, 38.56%±3.70%)、3D-CRT+IMRT组(49.12%±3.03%,38.38%±3.56%)明显少于IMRT组[(77.18%±8.01%, 53.07%±6.85%),q=20.35、20.05、12.10、12.24, P<0.01],3D-CRT+E、3D-CRT+IMRT两组之间差异无统计学意义(q=0.30、0.14, P＞0.05);患侧肺V₂₀,3D-CRT+IMRT组(26.57%±2.51%)、IMRT组(25.22%±2.77%)优于3D-CRT+E组[(31.79%±3.00%), q=5.27、8.21, P<0.01],3D-CRT+IMRT、IMRT两组之间差异无统计学意义(q=2.76, P＞0.05);V453种计划之间差异无统计学意义(F=0.69, P＞0.05)。结论 在PMRT中应用3D-CRT+IMRT照射技术在不增加设备投入的情况下能有效地降低患侧肺受照射剂量。     

我国CT检查成年人辐射剂量诊断参考水平的建立历程及解读

经过放射诊断专家、影像技术专家、辐射防护专家和专业技术人员10多年的探索,一项基于大规模国内调查数据而建立的CT检查成年人辐射剂量诊断参考水平(diagnostic reference level,DRL)以国家卫生行业标准(WS/T 637-2018)形式发布。其制定原则和方法符合国际惯例和我国的实际情况,基本上涵盖了我国成年人常见CT检查项目,与国外的DRL比较,整体处于一个合理或较低的剂量水平。给出的50%分位数(可能达到水平)和25%分位数(异常低剂量的提示水平)作为辐射剂量优化指导的额外工具。在日常放射诊断活动中,使辐射剂量与图像质量、临床诊断任务相匹配,降低非正当过高或过低剂量的发生频率。     

Low-dose-rate iodine-125 seed air kerma strength measurement intercomparison

PurposeThe purpose of this study was to investigate the rate of compliance of air kerma strength (AKS) measurements of iodine-125 (I-125) seeds with international recommendations by departments in Australia and determine the potential impact of noncompliance.Methods and MaterialsTo achieve this aim, we present an intercomparison of AKS measurements for a single I-125 seed performed by 11 radiotherapy departments in Australia. Measurements were performed at two sites, with each participating department traveling to one of the two host sites and measuring the AKS using their own equipment and local protocols. Each of the AKS measurements was compared with each other and the manufacturer-certified AKS.ResultsNine of the 11 participating departments measured AKS fell within ±3% of the manufacturer's calibration certificate value, whereas all participating departments measured AKS within ±5% of the manufacturer's calibration certificate value. The total spread of the measured AKS among the 11 departments was 7.7%. Only two of the 11 participating departments complied with international recommendations and had their well chamber calibrated within the last 2 years. In addition, 2 of the 11 departments used a well chamber calibrated that was calibrated with a different seed model used during the intercomparison, whereas 4 of the 11 departments calibrated their well chamber “in-house” using a factory-calibrated seed provided by the seed manufacturer.ConclusionsA significant variation in the methods used and frequency of calibration of well chambers were observed among the participating departments. The results of this study support the international recommendations on frequency and methodology of well chamber calibration. Failure to follow these recommendations significantly increases the uncertainty in AKS measurement of I-125 seeds.     

Spectrum of diagnostic errors in radiology

Diagnostic errors are important in all branches of medicine because they are an indication of poor patient care. Since the early 1970s, physicians have been subjected to an increasing number of medical malpractice claims. Radiology is one of the specialties most liable to claims of medical negligence. Most often, a plaintiff's complaint against a radiologist will focus on a failure to diagnose. The etiology of radiological error is multi-factorial. Errors fall into recurrent patterns. Errors arise from poor technique, failures of perception, lack of knowledge and misjudgments. The work of diagnostic radiology consists of the complete detection of all abnormalities in an imaging examination and their accurate diagnosis. Every radiologist should understand the sources of error in diagnostic radiology as well as the elements of negligence that form the basis of malpractice litigation. Error traps need to be uncovered and highlighted, in order to prevent repetition of the same mistakes. This article focuses on the spectrum of diagnostic errors in radiology, including a classification of the errors, and stresses the malpractice issues in mammography, chest radiology and obstetric sonography. Missed fractures in emergency and communication issues between radiologists and physicians are also discussed.     

IAEASSDL放疗剂量水平电离室校准因子的国际比对

目的参加国际原子能机构(IAEA)组织的二级标准剂量学实验室(SSDL)比对,引入水吸收剂量校准因子,检查SSDL60Co放疗剂量标准的准确度,保证校准程序的可靠性和一致性.方法本SSDL给出电离室的60Co γ射线比释动能校准因子和水吸收剂量校准因子,然后将该电离室及其校准结果寄往IAEA剂量学实验室,对其进行评价,给出比对的偏差.结果比释动能校准因子比对的偏差为-0.5%,水吸收剂量校准因子的比对偏差为0.4%.结论按照IAEA要求,该项比对的最大允许偏差为±1.5%,所以这次比对结果是合格的.     

HDR brachytherapy well chamber calibration and stability evaluated over twenty years of clinical use

PurposeThe purpose of the study was to establish, using a retrospective analysis of existing hospital records, the long-term stability and accuracy of a high-dose-rate brachytherapy well chamber. This should be assessed to determine reliability and appropriate calibration frequency. The accrual of long-term data that demonstrates the stability of our chamber may inform others of the performance they might expect from similar equipment.Methods and MaterialsWe evaluated air kerma strength measurements made with the PTW 32002 (Nucletron 077.091) high-dose-rate well chamber on 72 ¹⁹²Ir sources over an 18-year period and the seven calibrations of that chamber which span a 27-year period.ResultsConsecutive air kerma strength measurements agreed within 0.01% on average. The chamber measurement agreed with the source specification within 0.02% on average, but was up to 1.4% during some calibration periods. The chamber calibration coefficient varied by a maximum of 5% over seven chamber calibration measurements.ConclusionsThe constancy of the well chamber current compared with the source manufacturer suggests that our chamber has been stable to better than 2% over a period of 18 years. Although the chamber has received different calibration coefficients over time, these coefficients are within the combined uncertainties of any two calibrations and are consistent with the chamber being stable. The agreement we have observed between clinical measurements and the source manufacturer would justify an action level for further investigation of 1%, for this specific chamber.     

Local diagnostic reference levels for typical radiographic procedures

Purpose

To establish local diagnostic reference levels (DRL) for typical radiographic examinations in a fully digital imaging institution.

Methods

The initial survey included 6 standard radiographic projections performed in 19 computed radiography (CR) and digital radiography (DR) rooms. Because of the expected difference in the performance, the local reference levels were analysed separately for those 2 modalities. Data of 226 average size adult patients were included in the analysis. Entrance surface dose (ESD) was calculated from the recorded radiographic techniques and tube radiation output measurements. After observing wide variations in the results of the patient survey, the examinations were repeated by using anthropomorphic phantoms. Initial efforts to understand the reasons for dose variations were focused on CR chest, abdomen, pelvis, and lumbar spine examinations.

Results

The average size patient doses for similar examinations were lower in the DR rooms than in the CR rooms by factors that ranged from 1.2 to 3, with the exception of the chest examination. Standardization of the CR exposure index value allowed us to decrease ESD by 21%-30%. Detector sensitivity had an insignificant effect (2%) on ESD; proper collimation lowered the dose by 17%. However, the major effect, up to 46% difference, was found because of antiscatter grids cutoff.

Conclusion

Modality specific local diagnostic reference levels for standard examinations have been established in a large digital imaging department with hybrid modalities. Typically the local reference values were lower than those recommended in Safety Code 35, except for CR chests. Factors that affect the dose variations have been investigated and determined.     

Learning from diagnostic errors: a good way to improve education in radiology

Purpose

To evaluate the causes and the main categories of diagnostic errors in radiology as a method for improving education in radiology.

Material and methods

A Medline search was performed using PubMed (National Library of Medicine, Bethesda, MD) for original research publications discussing errors in diagnosis with specific reference to radiology. The search strategy employed different combinations of the following terms: (1) diagnostic radiology, (2) radiological error and (3) medical negligence. This review was limited to human studies and to English-language literature. Two authors reviewed all the titles and subsequently the abstracts of 491 articles that appeared pertinent. Additional articles were identified by reviewing the reference lists of relevant papers. Finally, the full text of 75 selected articles was reviewed.

Results

Several studies show that the etiology of radiological error is multi-factorial. The main category of claims against radiologists includes the misdiagnoses. Radiologic “misses” typically are one of two types: either missed fractures or missed diagnosis of cancer. The most commonly missed fractures include those in the femur, the navicular bone, and the cervical spine. The second type of “miss” is failure to diagnose cancer. Lack of appreciation of lung nodules on chest radiographs and breast lesions on mammograms are the predominant problems.

Conclusion

Diagnostic errors should be considered not as signs of failure, but as learning opportunities.     

成年人CT扫描中辐射剂量和诊断参考水平的探讨

目的 通过全国范围内CT辐射剂量的调查,了解成年人辐射剂量的现状,进而探讨成年人CT的诊断参考水平不符,需要根据我国的实际建立自己的DRL。方法 2015年9月至2016年3月在全国30个省、自治区、直辖市调查168家医院,其中三级和二级医院各约占一半。随机调查年度状态检测合格的168台CT,包括了临床应用中普遍使用的品牌和型号。每台CT收集头颅、鼻窦、颈部、胸部、腹部、盆腔、腰椎、尿路造影、冠状动脉CT血管造影（CTA）、颅脑CTA、颈部CTA和胸腹CTA共12个检查项目、每个项目10个随机病例。以容积CT剂量指数（CTDI_vol）和剂量长度乘积（DLP）作为剂量参量,每个检查项目的所有数据按照大小排序,取25%、50%和75%位数,其中75%位数为参考水平。所得剂量数值与国际相关放射防护组织发布的DRL进行比较。结果 共收集16 244个标准体型成年病例的剂量数据,经逐一检查剔除274个无效数据,剩余15 970个病例数据。全国范围内不同的CT使用单位,同一检查项目的CTDI_vol、DLP和扫描期项都有很大差异。与国际放射防护组织发布的数据相比,不同检查项目的诊断参考水平的差异程度各不相同,颅脑诊断水平与参考值相当、胸部腹部较低。剂量指数值最大的几种检查项目为头颅、冠状动脉CTA、颅脑CTA和鼻窦。尿路造影的CTDI_vol虽然仅为20 mGy,但DLP却高达2 620 mGy·cm。结论 我国现有的CT剂量水平与国际相关组织发布的诊断标准水平（DRL）不符,需要根据我国的实际建立自己的DRL。     

Dosimetry errors in endovascular high-dose-rate brachytherapy

Monte Carlo data were used to demonstrate the dosimetry of the microSelectron high-dose-rate (HDR) iridium 192 (¹⁹²Ir) stepping source. These data were used to assess the accuracy of the Nucletron brachytherapy planning system (BPS version 13) for peripheral vessel endovascular brachytherapy. Dose rates from the high-dose-rate (HDR) source are calculated using the Monte Carlo code MCNP4A. Calculations are made at 0.25-cm intervals in the longitudinal direction on sleeves of radii of 1 and 0.25 cm. The Monte Carlo data are summed and weighted to simulate the longitudinal dose distribution at a distance of 1 and 0.25 cm from an ¹⁹²Ir source stepping through a straight pathway. A comparison is made between the simulated Monte Carlo dosimetry and the Nucletron brachytherapy planning system’s dosimetry. This study illustrates and quantifies the dosimetric errors at small distances associated with a point source dose calculation algorithm. The effects of step size, dwell time optimization, and active length on the accuracy of BPS v.13 for HDR endovascular brachytherapy are demonstrated.     

Guidelines and algorithms: strategies for standardization of referral criteria in diagnostic radiology

Guidelines can be regarded as special forms of algorithms and have been shown to be useful tools for supporting medical decision making. With the Council Directive 97/43/Euratom recommendations concerning referral criteria for medical exposure have to be implemented into national law of all EU member states. The time- and cost-consuming efforts of developing, implementing, and updating such guidelines are balanced by the acceptance in clinical practice and eventual better health outcomes. Clearly defined objectives with special attention drawn on national and regional differences among potential users, support from organisations with expertise in evidence-based medicine, separated development of the evidence component and the recommendations component, and large-scale strategies for distribution and implementation are necessary. Editors as well as users of guidelines for referral criteria have to be aware which expectations can be met and which cannot be fulfilled with this instrument; thus, dealing with guidelines requires a new form of "diagnostic reasoning" based on medical ethics.     

A Nordic survey of patient doses in diagnostic radiology

The aim of this study was to test the applicability of the guidance levels for patient doses cooperatively set by the radiation protection authorities in the five Nordic countries. The kerma-area product (KAP) for five conventional radiological examination types was obtained from several hospitals in each of the Nordic countries. The number of radiographic images and fluoroscopy time were also registered, and the mean values for each examination type and hospital were established based on a representative number of patients (40–100 kg). The results indicate that the situation is very similar in the five Nordic countries, even though some differences were identified. Most of the hospitals demonstrated lower doses than the proposed guidance levels for chest, probably explained by use of faster film/screen combinations during the past decade. An increased use of fluoroscopy for positioning was observed for radiographic examinations of lumbar spine and urography. Large variations in patient doses were found for barium enema depending on the use of fluorospot or 100-mm camera vs full-format film, the range in fluoroscopy times, dose rate, and field size. The guidance levels for lumbar spine (10 Gy × cm²), pelvis (4 Gy × cm²), urography (20 Gy × cm²), and barium enema (50 Gy × cm²) seem to reflect the present quality of X-ray equipment and examination techniques in the Nordic countries. The guidance levels for chest (1 Gy × cm²) should be lowered to 0.6 Gy × cm². Received: 28 February 2000, Revised: 18 May 2000, Accepted: 22 May 2000     

Contemporary Interventional Radiology Dosimetry: Analysis of 4,784 Discrete Procedures at a Single Institution

PurposeTo report dosimetry of commonly performed interventional radiology procedures and compare dose analogues to known reference levels.Materials and MethodsDemographic and dosimetry data were collected for gastrostomy, nephrostomy, peripherally inserted central catheter placement, visceral arteriography, hepatic chemoembolization, tunneled catheter placement, inferior vena cava filter placement, vascular embolization, transjugular liver biopsy, adrenal vein sampling, transjugular intrahepatic portosystemic shunt (TIPS) creation, and biliary drainage between June 12, 2014, and April 26, 2018, using integrated dosimetry software. In all, 4,784 procedures were analyzed. The study included 2,691 (56.2%) male subjects and 2,093 (43.8%) female subjects with mean age 55 ± 21 years (range: 0-104 years) and with mean weight of 76.9 ± 29.4 kg (range: 0.9-268.1 kg). Fluoroscopy time, dose area product (DAP), and reference dose were evaluated.ResultsTIPS had the highest mean fluoroscopy time (49.1 ± 16.0 min) followed by vascular embolization (25.2 ± 11.4 min), hepatic chemoembolization (18.8 ± 12.5 min), and visceral arteriography (17.7 ± 3.2 min). TIPS had the highest mean DAP (429.2 ± 244.8 grays per square centimeter [Gy·· cm²]) followed by hepatic chemoembolization (354.6 ± 78.6 Gy·· cm²), visceral arteriography (309.5 ± 39.0 Gy·· cm²), and vascular embolization (298.5 ± 29 Gy·· cm²). TIPS was associated with the highest mean reference dose (2.002 ± 1.420 Gy) followed by hepatic chemoembolization (1.746 ± 0.435 Gy), vascular embolization (1.615 ± 0.381 Gy), and visceral arteriography (1.558 ± 1.720 Gy). Of the six procedures available for comparison with the reference levels, the mean fluoroscopy time, DAP, and reference dose for each procedure were below the proposed reference levels.ConclusionAdvances in image acquisition technology and radiation safety protocols have significantly reduced the radiation exposure for a variety of interventional radiology procedures.     

蒙特卡罗模拟在放射诊断辐射剂量估算和优化中的应用

放射诊断成像的频次和对公众的累积剂量不断提升, 带来的辐射风险引起广泛关注, 但人体所接受辐射剂量的准确测量很难实现。蒙特卡罗模拟作为以概率统计理论为指导的数值计算方法, 已应用于各种放射诊断成像的剂量评估、成像优化和辐射防护。本文就蒙特卡罗方法的原理、蒙特卡罗模拟的建模过程及其在放射诊断剂量估算的应用进展进行综述。     

Dosimetry of iodine-123 iodobenzamide in healthy volunteers

The distribution of the dopamine D₂-receptor specific ligand iodine-123 (S)-(–)-2-hydroxy-3-iodo-6-methoxy-N[(1-ethyl-2-pyrrolidinyl)methyl]-benzamide (1231-IBZM) was investigated in human adults from whole-body scans, blood samples and urine collected up to 48 h after injection. Results from the present study performed in six healthy volunteers were combined with those of five volunteers from a previous study. Using the brain, liver, lungs and spleen as source organs, the MIRD method was applied to calculate the absorbed radiation dose of the radioligand in various organs. The thyroid (despite blockage), gall-bladder wall, large intestinal walls and spleen received the highest absorbed doses. The average effective dose equivalent of ¹²³I-IBZM for adults was estimated to be 0.034 mSv/MBq. The absorbed dose to the thyroid may be a limiting factor for 1231-IBZM studies in children.