The benefits of biomedical research involving humans are well recognised, along with the need for conformity to international standards of science and ethics. When human research involves radiation imaging procedures or radiotherapy, an extra level of expert review should be provided from the point of view of radiological protection. The relevant publication of the International Commission for Radiological Protection (ICRP) is now three decades old and is currently undergoing an update. This paper aims to provoke discussions on how the risks of radiation dose and the benefits of research should be assessed, using a case study of diagnostic radiology involving volunteers for whom there is no direct benefit. Further, the paper provides the current understanding of key concepts being considered for review and revision—such as the dose constraint and the novel research methods on the horizon, including radiation biology and epidemiology. The analysis revisits the perspectives described in the ICRP Publication 62, and considers the recent progress in both radiological protection ethics and medical research ethics.

This study represents the first national survey conducted in Sri Lanka to establish national diagnostic reference levels (NDRLs) for screening and diagnostic acquisitions in digital mammography (2D-DM) and digital breast tomosynthesis (DBT). Additionally, the study investigated the relationship between average glandular dose (AGD) and compressed breast thickness (CBT) and introduced a novel concept called dose range bands (DRBs) as a tool for optimizing radiation dose in mammography. DICOM metadata was used to extract dose data and exposure parameters from women undergoing either screening (350) or diagnostic (750) DM. The analysis included both craniocaudal and mediolateral oblique views of each breast, acquired using 2D-DM and DBT imaging techniques. The NDRL (AGD per view) was 1.97 mGy and 2.01 mGy for diagnostic DM and DBT, respectively. The corresponding NDRLs for screening acquisition were 2.44 mGy and 2.30 mGy. The mean DBT/DM AGD ratio was 1.39 and 0.97 for diagnostic and screening, respectively. Further, the association between the average glandular AGD per view and CBT is stronger in DBT than in 2D-DM. The study findings highlight the need for standardisation of compression practices, considering factors such as the radiographer’s experience, imaging equipment, breast density, age, breast size, and pain threshold.

The objective of this study is to update the national and regional indoor radon concentrations in South Korea and assess indoor radon exposure. Based on the previously published survey results and the collected measurement data of surveys conducted since 2011, a total of 9271 indoor radon measurement data covering 17 administrative divisions are finally used for analysis. The annual effective dose from the indoor radon exposure is calculated using dose coefficients recommended by the International Commission on Radiological Protection. The population-weighted average indoor radon concentration was estimated to be a geometric mean of 46 Bq m−3 (GSD = 1.2) with 3.9% of all samples showing values exceeding 300 Bq m−3. The regional average indoor radon concentration ranged from 34 to 73 Bq m−3. The radon concentrations in detached houses were relatively higher than those in public buildings and multi-family houses. The annual effective doses to the Korean population due to indoor radon exposure were estimated to be 2.18 mSv. The updated values in this study might better represent the national indoor radon exposure level in South Korea because they contain more samples and cover a wider range of geographical areas than previous studies.

The consideration of risks from medical diagnostic x-ray examinations and their justification commonly relies on estimates of effective dose, although the quantity is actually a health-detriment-weighted summation of organ/tissue-absorbed doses rather than a measure of risk. In its 2007 Recommendations, the International Commission on Radiological Protection (ICRP) defines effective dose in relation to a nominal value of stochastic detriment following low-level exposure of 5.7 × 10−2 Sv−1, as an average over both sexes, all ages, and two fixed composite populations (Asian and Euro-American). Effective dose represents the overall (whole-body) dose received by a person from a particular exposure, which can be used for the purposes of radiological protection as set out by ICRP, but it does not provide a measure that is specific to the characteristics of the exposed individual. However, the cancer incidence risk models used by ICRP can be used to provide estimates of risk separately for males and females, as a function of age-at-exposure, and for the two composite populations. Here, these organ/tissue-specific risk models are applied to estimates of organ/tissue-specific absorbed doses from a range of diagnostic procedures to derive lifetime excess cancer incidence risk estimates; the degree of heterogeneity in the distribution of absorbed doses between organs/tissues will depend on the procedure. Depending on the organs/tissues exposed, risks are generally higher in females and notably higher for younger ages-at-exposure. Comparing lifetime cancer incidence risks per Sv effective dose from the different procedures shows that overall risks are higher by about a factor of two to three for the youngest age-at-exposure group, 0–9 yr, than for 30–39 yr adults, and lower by a similar factor for an age-at-exposure of 60–69 yr. Taking into account these differences in risk per Sv, and noting the substantial uncertainties associated with risk estimates, effective dose as currently formulated provides a reasonable basis for assessing the potential risks from medical diagnostic examinations.

The International Commission on Radiation Units and Measurements (ICRU) proposed a new set of operational quantities for radiation protection for external radiation in its Report Committee 26 (ICRU 95). The new proposal aims to improve the coherence between the operational quantities and the definitions of the protection quantities in the recommendations of the International Commission on Radiological Protection set out in 2007 (Ann. ICRP 37). It is expected that this change in operational quantities will impact current dosimeter designs. Although for many photon energies, the conversion coefficients from physical field quantities to the new operational quantities will change relatively little, for radiation fields with low energy photon components, such as medical x-ray applications, there will be a significant decrease in the values of the conversion coefficients. This means that the numerical values of the new operational quantities will be much lower for the same radiation field. These values will be closer to the effective dose, but this change can still cause confusion for medical staff. It is important to examine the effect of the new set of dose conversion coefficients on the personal dose in realistic radiation fields. We performed a study to assess the effect of changing the definition of the operational quantity, personal dose equivalent ( Hp ), in realistic radiation fields in interventional radiology (IR) workplaces. The x-ray tube kilovoltage peak (kVp) in IR ranges between 60 and 120 kV. The medical staff is exposed to the scattered photons which have a wide range of energies depending on the beam configuration and the patient size. The objective of this study is to ‘quantitatively’ estimate the impact of implementing the new ICRU quantities of Report 95 in IR radiation fields using Monte Carlo simulations. Simulations of 560 different configurations in IR were performed using MCNPX to calculate fluence binned per energy and angle of incidence. Hp and Hp(10) were then calculated for each configuration using dose conversion coefficients from fluence given by ICRU Reports 95 and 57, respectively. The results show that the mean of the ratio, Hp(10)/Hp , is 1.6 for all simulated scenarios. This reduction will correct the current overestimation of the effective dose and should result in better compliance with the dose limits in IR. However, it may also have negative consequences on the safety culture among the medical staff. Special care will be needed when interpreting these lower doses.

The purpose of this study was to acquire up-to-date information on nuclear medicine treatments in Europe and on the implementation of the requirements of the Basic Safety Standards Directive in HERCA Heads of the European Radiological Protection Competent Authorities (HERCAs) member states. An electronic survey was distributed to competent authorities of 32 HERCA member states. The questionnaire addressed 33 explicitly considered treatments using 13 different radionuclides, and for each treatment, a similar set of questions was included. Questions covered the use of treatments, hospitalisation of patients and radioactive waste management related to therapeutic nuclear medicine involving other radionuclides than the well-known 131I. The survey also covered justification of treatments, individual treatment planning, involvement of a medical physics expert (MPE) and radiation protection instructions given to the patient at the time of release. Responses were obtained from 20 HERCA countries. All of these countries used Na[131I]I for benign thyroid diseases and thyroid ablation of adults. 223RaCl2 (Xofigo®) for bone metastases, 177Lu-somatostatin analogues for neuroendocrine tumours and 177Lu-labelled PSMA for castration resistant prostate cancer (PC) and PC-metastases were used in 90%, 65% and 55% of countries, respectively. Only a few countries had specific criteria for hospitalisation and waste management for new therapeutic nuclear medicine. Regulatory requirements for justification of new therapeutic nuclear medicine were in place in almost all countries. Individual treatment planning was required for all therapies in 55% and for some therapies in 28% of the responding countries. Implementation of the requirement for MPEs to be closely involved in nuclear medicine practices varied to a great extend among countries. Almost all responding countries answered that some radiation protection instructions existed for patients released after treatment with radionuclides other than 131I treatment, however only few countries had developed specific guidelines in the field.

The accurate measurement of thoron activity concentration is an important issue in both thoron exposure evaluation and in reducing its influence on radon measurement. For radon monitors based on electrostatic collection technique and an alpha spectrometry analyser, air humidity and sampling flowrate are key factors influencing the sensitivity of thoron activity concentration measurement. For the purpose of improving thoron measurement sensitivity and stability, theoretical derivation and experimental studies were systemically performed in this study. The results show that thoron measurement sensitivity decreases as a negative exponential function with absolute humidity increasing, and the sensitivity of thoron is much lower than that of radon under the same conditions, which is mainly caused by the small value of the concentration ratio of thoron inside to outside of the chamber. When the air exchange rate of the measurement chamber (sampling flowrate/inner volume) increases, the measurement sensitivity of thoron gas first increases rapidly and then decreases slowly after reaching its maximum at the air exchange rate of 0.24 s−1. In practice, in the normal air exchange rate range (for example <0.05 s−1), increasing the sampling flowrate could greatly improve the thoron measurement sensitivity, which consequently suggests an effective way to update thoron measurement under the present conditions of the monitor.

In this work, the radon emanation coefficients for selected building materials that are most often used in Serbia for covering floor surfaces (concrete, concrete screed, granite, glazed ceramic tiles, marble, roofing tile, and terrazzo tile) were determined, and the influence of the material structure on their values. The concentration of 226Ra activity in the samples was determined using the gamma spectrometry method. Radon emanation was measured with the RAD7 device. The porosity of the samples was tested using mercury intrusion porosimetry and water absorption methods, and the structural analysis was performed using x-ray diffraction analysis and x-ray fluorescence analysis. The measured values of 226Ra activity concentrations were in the range (4.93–298) Bq kg−1, and the estimated values of the radon emanation coefficients were in the range (0.55–6.05) %. The obtained results indicate that the chemical and mineralogical composition, method of production, and the 226Ra activity concentration have an influence on the emanation of radon from the material. No significant correlation was found between the radon emanation coefficient and the open porosity of the material, most likely due to the inhomogeneous presence of pores of different dimensions in the materials. It was established that the total value of the emanation coefficient depends on the emanation coefficient for pores ⩽100 μm in size.

In 2012, the International Commission on Radiological Protection issued new recommendations, in publication 118, regarding the dose limits to the eye-lens. New analyses of historical exposure data had indicated that radiation-induced cataracts may appear at lower doses than previously assumed. This spurred largescale efforts in a variety of fields including dosimetry, radiation effects simulations, and the review of national regulatory limits. On the simulation side, much work led to the publication of dose rate conversion factors (DRCFs), to calculate the dose to the radiosensitive part of the eye-lens, and to the whole eye-lens as functions of the incident fluence of electron, photon, positron, and neutron radiation. The standard, ISO-15382 (2015 Radiological Protection—Procedures for Monitoring the Dose to the Lens of the Eye, the Skin and the Extremities), from the International Organization for Standardization (ISO), stated that the direct contact of a hot radioactive particle on the eye-lens represents a special contamination condition that must be considered. The aim of this work was to produce tabulated data of eye-lens dose rates, per activity (MBq), for a variety of radionuclides. In this work, the dose to the eye-lens from contamination directly in contact with the cornea, expressed in terms of DRCFs for eye-lens, in units of Gy h−1 MBq−1, are presented for 102 radionuclides of interest. These radionuclides were selected as they had been considered by the International Atomic Energy Agency of importance for skin dose. The method consisted of two steps. The first was the determination of the DRCFs for mono-energetic electrons and photons for a hot particle in contact with the eye-lens, followed by the folding of these quantities with the emissions of the radionuclides of interest. Contributions from spontaneous fission neutrons were considered separately. Exposure geometries for spherical hot particles of different dimensions, materials and locations on the cornea were considered. In addition, partial surface coverage of the cornea, consistent with an accidental exposure to a contaminated liquid, was also modelled. Resulting radionuclide DRCFs were verified, for a few specific geometries and radionuclides with dedicated Monte Carlo simulations. The final data are presented in several tables included in this paper.

Sheltering is one of the countermeasures used to mitigate radiation exposure during nuclear power plant accidents. The effectiveness of sheltering for inhalation exposure is often expressed by the reduction factor, which is defined as the ratio of the indoor to the outdoor cumulative radioactivity concentrations or doses. The indoor concentration is mainly controlled by the air exchange rate, penetration factor, and indoor deposition rate. Meanwhile, the air exchange rate depends on surrounding environmental conditions: the wind speed, leakage area normalised by the floor area of the house, and gross building coverage ratio. In this study, the ranges of the uncertainty of the reduction factors for particles and iodine in reactive gas form were investigated under various environmental conditions, and sensitivity analyses were conducted to understand the parameter with the most influence on the uncertainty of the reduction factor. From the results of the uncertainty analyses, the calculated reduction factor was highly variable depending on the environmental condition and the airtightness of the houses. The median and 95th percentile of the reduction factors for the older houses were 0.5 and 0.9 for particles and 0.07 and 0.4 for iodine in reactive gas form, respectively and these ranges were smaller for newer houses. From the results of the sensitivity analyses, the wind speed was the most influential parameter determining the reduction factor. Additionally, the wind speed was less influential for the reduction factor in newer houses.