Consistent Risk Management in a Changing World: Risk Equivalence in Fisheries and Other Human Activities Affecting Marine Resources and Ecosystems

A changing climate makes the evaluation of human impacts on natural systems increasingly uncertain and affects the risk associated with management decisions. This influences both the achievability and meaning of marine conservation and resource management objectives. A risk-based framework that includes a risk equivalence approach in the evaluation of the potential consequences from human activity, can be a powerful tool for timely and consistent handling of environmental considerations in management advice. Risk equivalence permits a formal treatment of all sources of uncertainty, such that objectives-based management decisions can be maintained within acceptable risk levels and deliver outcomes consistent with expectations. There are two pathways to risk equivalence that can be used to account for the short-term and longer-term impacts of a changing environment: adjusting the degree of exposure to human pressure and adjusting the reference levels used to measure the risk. The first uses existing data and knowledge to derive risk conditioning factors applied to condition management advice on environmental departures from baseline conditions. The second is used to formalise the review and update of management objectives, reference levels and risk tolerances, so they remain consistent with potential consequences from human activity under new biological, ecological and socio-economic realities. A risk equivalence approach is about adapting existing practice to frame environmental considerations within objectives-based risk frameworks, systematically exploring alternative scenarios and assumptions, and conditioning management advice on environmental status. It is applicable to the management of all human activities impacting biological and ecological systems. Concepts of risk, risk conditioning factors, and incremental changes in risk, provide a common currency for the inclusion and communication of environmental effects into advice. Risk equivalence can ensure timely delivery of robust management advice accounting for demonstrated, anticipated or projected environmental effects. This can guide management decisions in a changing world, and greatly facilitate the implementation of an ecosystem approach for the management of human activities.

Establishing local diagnostic reference levels for adult computed tomography in Morocco

In Morocco, the radiation doses received by adult patients are increasing due to the number of CT examinations performed and the larger number of computed tomography (CT) scanners installed. The aim of this study was to evaluate the radiation doses received by patients for the most common adult CT examinations in order to establish local diagnostic reference levels (DRLs). Data from 1016 adult patients were collected during 3 months from four Moroccan hospitals. Dose length product (DLP) and volumetric computed tomography dose index (CTDIvol) were evaluated by determining the 75th percentile as diagnostic reference levels for the most common examinations including head, chest and abdomen. The DRL for each examination was compared with other studies. The established DRLs in Morocco in terms of CTDIvol were 57.4, 12.3 and 10.9 for CT examinations of the head, chest, abdomen, respectively. For DLP, they were 1020, 632 and 714, respectively. These established DRLs for CTDIvol were almost similar to the UK DRLs at all examinations, higher than the Egyptian DRLs and lower than the Japanese DRLs at the head CT examination, lower than the DRLs from Egypt and Japan at the CT abdomen examination. In terms of DLP, the DRLs were higher than those of the British studies, lower than those of the Egyptian and Japanese studies at the head CT examination were higher at chest CT and lower at abdominal CT than those of all selected studies. The higher level of established DRLs in our study demonstrates the requirement of an optimization process while keeping a good image quality for a reliable diagnosis.

Determinación de los niveles de referencia de dosis (DRL) para diagnóstico de baja y media complejidad en Servicios Especiales de Salud Hospital Universitario de Caldas de Colombia (SES-HUC)

Objetivo: Los niveles de referencia de dosis para diagnóstico (dose reference levels - DRL) son una herramienta útil para optimizar la protección radiológica en exposiciones médicas de diagnóstico. Su determinación es un requisito para obtener la licencia de uso de equipos emisores de radiación ionizante en los servicios de imágenes diagnósticas de Colombia. El objetivo de este trabajo fue establecer los valores de DRL institucionales con diversos equipos emisores de radiación ionizante para los procedimientos de diagnósticos más comunes asociados a áreas anatómicas típicas. Metodología: Este estudio fue realizado en dos equipos de radiología convencional, un equipo de mamografía, un equipo de tomografía computada (TC) y un equipo de fluoroscopia tipo arco en C. La muestra estadística se clasificó de acuerdo con los tipos de estudio, las áreas anatómicas de interés, tamaño y rangos de pesos de pacientes. Los tamaños de la muestra variaron según la técnica diagnóstica, siguiendo recomendaciones del documento técnico “Diagnostic reference levels in medical imaging. ICRP Publication 135”. Los datos de la dosis entregada a cada paciente se obtuvieron registrando el valor de dosis estimado por el equipo de adquisición de imagen. El análisis estadístico se hizo por medio de diagramas de cajas y distribuciones de frecuencias, donde el tercer cuartil se definió como el valor de DRL para cada técnica de adquisición de imagen. Resultados: Los valores obtenidos de DRL para radiografía convencional fueron inferiores a 15 dGy.cm2 para pacientes con pesos entre 50-80 kg, e inferiores a 27 dGy.cm2 para pacientes de más de 80 kg. Para mamografía, los valores de DRL a través de la dosis glandular media fueron inferiores a 2,7 mGy para proyecciones oblicuas con espesores entre 45-94 mm. Los índices de dosis en tomografía computarizada en volumen (CTDIvol) y los valores de producto dosis-longitud (DLP) fueron inferiores a 41,4 mGy y 907 mGy.cm respectivamente, obteniendo los mayores valores en cráneo y los menores en abdomen para pacientes entre50 y 80 kg. En procedimientos con arco en C, los valores obtenidos de DRL fueron iguales a 2,69 Gy.cm2 para colangiopancreatografía retrógrada endoscópica (CPRE), 2,88 Gy.cm2 para histerosalpingografía (HSG) y 9,22 Gy.cm2 para colon por enema. Conclusiones: Los niveles de referencia de dosis en procedimientos diagnósticos obtenidos en este estudio para SES-HUC, han arrojado valores comparables a los publicados por otros autores en análisis similares, aplicando métodos de análisis sugeridos por organismos internacionales.

Paediatric diagnostic reference levels for common radiological examinations using the European guidelines

Objective: The purpose of this study was to explore the feasibility to determine regional diagnostic reference levels (RDRLs) for paediatric conventional and CT examinations using the European guidelines and to compare RDRLs derived from weight and age groups, respectively. Methods: Data were collected from 31 hospitals in 4 countries, for 7 examination types for a total of 2978 patients. RDRLs were derived for each weight and age group, respectively, when the total number of patients exceeded 15. Results: It was possible to derive RDRLs for most, but not all, weight-based and age-based groups for the seven examinations. The result using weight-based and age-based groups differed substantially. The RDRLs were lower than or equal to the European and recently published national DRLs. Conclusion: It is feasible to derive RDRLs. However, a thorough review of the clinical indications and methodologies has to be performed previous to data collection. This study does not support the notion that DRLs derived using age and weight groups are exchangeable. Advances in knowledge: Paediatric DRLs should be derived using weight-based groups with access to the actual weight of the patients. DRLs developed using weight differ markedly from those developed with the use of age. There is still a need to harmonize the method to derive solid DRLs for paediatric radiological examinations.

Diagnostic reference levels in digital mammography: A systematic review

Diagnostic reference levels (DRLs) in digital mammography (DM) serve as a useful benchmark for dose monitoring and optimization, allowing comparison amongst countries, institutions and mammography units. A systematic review of DRLs in DM, published in 2014, reported a lack of consistent and internationally accepted protocol in DRLs establishment, thereby resulting in wide variations in methodologies which complicates comparability between studies. In 2017, the International Commission of Radiation Protection (ICRP) published additional guidelines and recommendations to provide clarity in the protocol used in DRLs establishment. With the continuing evolvement of technology, optimization of examinations and updates in guidelines and recommendations, DRLs should be revised at regular intervals. This systematic review aims to provide an update and identify a more consistent protocol in the methodologies used to establish DRLs. Searches were conducted through Web of Science, PubMed-MEDLINE, ScienceDirect, CINAHL and Google Scholar, which resulted in 766 articles, of which 19 articles were included after screening. Relevant data from the included studies were summarized and analyzed. While the additional guidelines and recommendations have provided clarifications in the methodologies used in DRLs establishment, such as data source (i.e., the preference to use data derived from patient instead of phantoms to establish DRLs), protocol (i.e., stratification of DRLs by compressed breast thickness and detector technology, and the use of median value for DRLs quantity instead of mean) and percentiles used to establish DRLs (i.e., set at the 75th percentile with a minimum sample size of 50 patients), other differences such as the lack of a standard dose calculation method used to estimate mean glandular dose continues to complicate comparisons between studies and different DM systems. This systematic review update incorporated the updated guidelines and recommendations from ICRP which will serve as a useful resource for future research efforts related to DRLs, dose monitoring and optimization.

Establishment of national diagnostic reference levels (NDRL) for computed tomographic (CT) procedures in Sri Lanka: first nation-wide dose survey

The main purpose of this study was to establish the national diagnostic reference levels (NDRLs) for common CT procedures for the first time in Sri Lanka. Patient morphometric, exposure parameters, and dose data such as volume CT dose index (CTDIvol) and dose length product (DLP) were collected from 5666 patients who underwent 22 procedure types. The extreme dose values were filteblue before analysis to ensure that the data comes from standard size patients. The median of the dose distribution was calculated for each institution, and the third quartile value of the median distribution was consideblue as the NDRL. Based on the inclusion and exclusion criteria, 4592 patients data from 17 procedure types were consideblue for NDRL establishment covering 41\% of the country's total CT machines. The proposed NDRLs based on CTDIvol and DLP for non-contrast (NC) head:82.2 mGy/1556 mGy.cm, contrast-enhanced (CE) head: 82.2 mGy/1546 mGy.cm, chest-NC:7.4 mGy/350 mGy.cm, chest-CE:8.3 mGy/464 mGy.cm, abdomen NC:10.5 mGy/721 mGy.cm, abdomen arterial (A) phase:13.4 mGy/398 mGy.cm, abdomen venous (V) phase:10.8 mGy/460 mGy.cm, abdomen delay (D) phase:12.6 mGy/487 mGy.cm, sinus NC:30.2 mGy/452 mGy.cm, lumbar spine--NC:24.1 mGy/1123 mGy.cm, neck-NC:27.5 mGy/670 mGy.cm, high resolutions CT (HRCT) of chest:10.3 mGy/341 mGy.cm, kidney, ureter and bladder (KUB) NC:19.4 mGy/929 mGy.cm, chest to pelvis (CAP) NC:10.8 mGy/801 mGy.cm, CAP-A:10.4 mGy/384 mGy.cm, CAP-V:10.5 mGy/534 mGy.cm and CAP-D:16.8 mGy/652 mGy.cm. Although the proposed NDRLs are comparable with other countries, the observed broad dose distributions between the CT machines within the country indicate that dose optimisation strategies for Sri Lanka should be implemented for most of the CT facilities.