Guidance on prevention of unintended and accidental radiation exposures in nuclear medicine.

Nuclear medicine (NM) procedures for diagnosis and treatment of disease are performed routinely in hospitals throughout the world. These involve preparation and administration to patients of pharmaceuticals labelled with radioactive material. The International Atomic Energy Agency (IAEA) and the World Health Organisation highlighted the need for improvement in prevention of medical radiation incidents and accidents in the Bonn Call-for-Action in 2012. An IAEA Technical Meeting was held on prevention of unintended exposures and accidents in NM in 2018 to address the issue. Exposures can take place at any time when radioactive material is being produced and used, and the risk continues after procedures have been completed. Thus there is potential for staff or members of the general public to be exposed, as well as patients. This paper sets out guidelines for incident prevention based on presentations and discussions at the meeting, and review of reports from the literature. It deals with potential incidents in in-house radionuclide production, radiopharmaceutical preparation, administration to patients, and following a procedure, as well as aspects in management of radioactive materials. Special attention has been paid to therapeutic procedures, as these have the potential to cause more harm to patients from erroneous administrations, including tissue reactions from extravasation of radiopharmaceutical, and could lead to significant contamination events. Administration of NM therapy is generally contraindicated in pregnancy. Identification of any patient who may be pregnant is crucial and it might be necessary to verify this with a pregnancy test for patients within the age band considered to be fertile. Inclusion of NM therapy incidents in the IAEA automated reporting system SAFRON is recommended. In summary, the paper aims to highlight errors that could occur during different phases of NM procedures in order to aid prevention of incidents. The value of periodic audit in evaluating systems in place on a regular basis is emphasised. Approaches to incident investigation and follow-up are described, and the need to ensure corrective action is taken to address any deficiencies stressed.

Verbal and spatial working memory among drug-using HIV-infected men and women.

Working memory (WM) is a critical component of many neurocognitive functions. The literature has demonstrated consistently that WM impairment is more frequent and severe among substance-dependent individuals (SDIs) infected with HIV compared with uninfected SDIs; however, the SDIs who participated in these previous studies were primarily male. There are few published data on WM performance among HIV+ women with or without substance use disorders, and essentially no direct comparisons of WM performance between HIV+ men and women, regardless of substance use. We investigated potential sex and serostatus effects on WM among a sample of 360 SDIs (114 with HIV; 66% female) verified abstinent from alcohol and drugs of abuse at testing and generally comparable on substance use and comorbid characteristics. Participants were tested with the n-back task, a well-established WM measure that is sensitive to HIV-associated cognitive impairment. HIV+ men and women performed spatial and verbal versions of the n-back significantly less accurately compared with HIV- participants. Women showed slower response times compared with men on both versions, regardless of HIV serostatus. Individuals dependent on cocaine showed faster RTs compared with non-dependent users, but this effect was not apparent among opioid- or alcohol-dependent groups. Findings on n-back accuracy are consistent with our previous proposal that WM impairment represents a signature deficit among HIV+ SDIs; however, WM impairment appears less common among HIV+ women without a substance use history. The pattern of sex differences in response speed but serostatus effects on response accuracy is comparable to a recent report by our group of sex differences in learning speed but serostatus effects on delayed recall.

Effects of sex and HIV serostatus on spatial navigational learning and memory among cocaine users.

Spatial learning and memory are critically dependent on the integrity of hippocampal systems. Functional MRI and neuropathological studies show that hippocampal circuitry is prominently affected among HIV-seropositive individuals, but potential spatial learning and memory deficits have not been studied in detail in this population. We investigated the independent and interactive effects of sex and HIV serostatus on performance of a spatial learning and memory task in a sample of 181 individuals with a history of cocaine dependence. We found that men showed faster times to completion on immediate recall trials compared with women and that delayed recall was significantly poorer among HIV-infected compared with HIV-uninfected participants. Additionally, a sex × serostatus effect was found on the total number of completed learning trials. Specifically, HIV-infected men successfully completed more learning trials compared with HIV-infected women. Results are discussed in the context of recent reports of sex and HIV serostatus effects on episodic memory performance.

Lessons from two cases of radiation induced skin injuries in fluoroscopic procedures in Bulgaria.

BACKGROUND: Radiation-induced injuries to patient skin as a result of fluoroscopy guided interventional procedures are infrequently reported, often misdiagnosed and there is a need to learn lessons from every injury. METHODS: This paper describes two cases of radiation induced skin injuries that are, to the best of our knowledge, the first ever reported cases from Bulgaria and possibly from Eastern Europe, and would thus have educational value. RESULTS: The important messages from the skin injuries reported here are: lack of awareness among part of the interventional specialists about the potential for radiation induced skin injury, misdiagnosis after injury happened because of lack of awareness and knowledge among general physicians, dermatologists and surgeons who followed up cases of skin injuries; the lack of system to monitor patients with relatively high exposure; the important role played by the medical physicist in diagnosing the injury and overall in initiating actions; the role of training and informational material displayed in interventional facilities. CONCLUSIONS: For avoidance of skin injuries from interventional procedures it is of utmost importance to implement a system that includes (a) regular monitoring of radiation dose parameters of the procedure; (b) established trigger values for reporting;

Unintended and accidental medical radiation exposures in radiology: guidelines on investigation and prevention.

This paper sets out guidelines for managing radiation exposure incidents involving patients in diagnostic and interventional radiology. The work is based on collation of experiences from representatives of international and national organizations for radiologists, medical physicists, radiographers, regulators, and equipment manufacturers, derived from an International Atomic Energy Agency Technical Meeting. More serious overexposures can result in skin doses high enough to produce tissue reactions, in interventional procedures and computed tomography, most notably from perfusion studies. A major factor involved has been deficiencies in training of staff in operation of equipment and optimization techniques. The use of checklists and time outs before procedures commence, and dose alerts when critical levels are reached during procedures, can provide safeguards to reduce the risks of these effects occurring. However, unintended and accidental overexposures resulting in relatively small additional doses can take place in any diagnostic or interventional x-ray procedure and it is important to learn from errors that occur, as these may lead to increased risks of stochastic effects. Such events may involve the wrong examinations, procedural errors, or equipment faults. Guidance is given on prevention, investigation, and dose calculation for radiology exposure incidents within healthcare facilities. Responsibilities should be clearly set out in formal policies, and procedures should be in place to ensure that root causes are identified and deficiencies addressed. When an overexposure of a patient or an unintended exposure of a foetus occurs, the foetal, organ, skin, and/or effective dose may be estimated from exposure data. When doses are very low, generic values for the examination may be sufficient, but a full assessment of doses to all exposed organs and tissues may sometimes be required. The use of general terminology to describe risks from stochastic effects is recommended rather than the calculation of numerical values, as these are misleading when applied to individuals.

A national patient dose survey and setting of reference levels for interventional radiology in Bulgaria.

OBJECTIVES: A national study on patient dose values in interventional radiology and cardiology was performed in order to assess current practice in Bulgaria, to estimate the typical patient doses and to propose reference levels for the most common procedures. METHODS: Fifteen units and more than 1,000 cases were included. Average values of the measured parameters for three procedures-coronary angiography (CA), combined procedure (CA + PCI) and lower limb arteriography (LLA)--were compared with data published in the literature. RESULTS: Substantial variations were observed in equipment and procedure protocols used. This resulted in variations in patient dose: air-kerma area product ranges were 4-339, 6-1,003 and 0.2-288 Gy cm(2) for CA, CA + PCI and LLA respectively. Reference levels for air kerma-area product were proposed: 40 Gy cm(2) for CA, 140 Gy cm(2) for CA + PCI and 45 Gy cm(2) for LLA. Auxiliary reference intervals were proposed for other dose-related parameters: fluoroscopy time, number of images and entrance surface air kerma rate in fluoroscopy and cine mode. CONCLUSIONS: There is an apparent necessity for improvement in the classification of peripheral procedures and for standardisation of the protocols applied. It is important that patient doses are routinely recorded and compared with reference levels. KEY POINTS: • Patient doses in interventional radiology are high and vary greatly • Better standardisation of procedures and techniques is needed to improve practice • Dose reference levels for most common procedures are proposed.

IAEA support to the radiation protection of patients in the time of the COVID-19 global pandemic.

The IAEA contribution to the radiation protection of patients during the global COVID-19 pandemic included a webinar on the use of CT and optimization for COVID-19 pneumonia, a survey with 137 responses from 84 sites across five continents, and a study on the CT utilization, protocols and patient doses with data from 62 healthcare sites from 34 countries. This paper outlines the main results of these efforts, which have been presented in the scientific literature and in several national trainings and international meetings.

Large differences in education and training of radiographers in Europe and Central Asia: Results from an IAEA coordinated study.

INTRODUCTION: Education and training of radiographers is known to be diverse between countries and regions. Under an IAEA project, this work collected data on radiographer education for the Europe and Central Asia region with a particular focus on radiation protection gaps and potential actions. METHODS: Following piloting, an electronic questionnaire was distributed to all national counterparts for the IAEA Technial Coopearation (TC) Europe region (n = 33 countries) and nominated national representatives. Contacts were additionally invited to a virtual workshop to discuss and rank common problems in education and training of radiographers and to propose potential solutions. RESULTS: Responses were received from 31 countries, including 14 from the European Union. Just over half of countries reported radiographer education being in higher education with 71% having program durations more than 3 years (range: 1 month-4 years). Programs included a spectrum of both clinical training and radiation protection hours with ten-fold variations noted across the region. Inclusion of core radiation protection topics within curricula varied similarly, as did radiographers' clinical involvement in both justification and optimisation between countries. Workshop participants identified five common training problems, namely education availability, lack of standardisation, radiation protection course quality, teamwork problems and lack of equipment. CONCLUSION: Radiographer education in the IAEA Europe region is heterogeneous with substantial differences in duration and quality of training programs between countries, which likely impact on quality of patient care delivered. Common problems have been identified and potential solutions proposed to focus quality improvement initiatives. IMPLICATIONS FOR PRACTICE: Radiographer education and training is diverse throughout the IAEA TC Europe region, with likely impacts on radiation protection practices applied. Clinical involvement of radiographers in justification and optimisation differs, potentially limiting adherence to radiation protection principles.

2021 NATIONAL DIAGNOSTIC REFERENCE LEVELS FOR PAEDIATRIC COMPUTED TOMOGRAPHY IN EGYPT.

OBJECTIVE: To establish national diagnostic reference levels (NDRLs) for most common paediatric computed tomography (CT) examinations in Egypt. METHODS: This was a prospective study that included all dedicated paediatric imaging centers in Egypt. Data from 1680 individual paediatric patients undergoing CT scanning of the head, chest and abdomen-pelvis were collected. Computed tomography dose indices were recorded, data were analysed and compared with the internationally published paediatric DRLs in14 countries. RESULTS: The Egyptian NDRLs of the CTDIvol (mGy) for head, chest and abdomen-pelvis scans among four paediatric age groups were found to be (23, 27, 28, 32, 4, 5, 6, 8, 5, 6, 7, 9) mGy, respectively; and the corresponding NDRLs of the DLP (mGycm) for head, chest and abdomen-pelvis scans were found to be (345, 428, 499, 637, 67, 85, 145, 215, 97, 135, 240, 320) mGycm, respectively. There were variations in the radiation doses between CT centers and identical scanners indicating the need for dose optimization. The NDRLs of the CTDIvol (mGy) and the DLP (mGycm) values were similar to or lower than international DRLs. CONCLUSION: This study summarizes the results of the first Egyptian Computed Tomography survey that provides national diagnostic reference levels for paediatric patients in Egypt. Despite the reasonable NDRLs values, the study depicted certain pros and cons concerning CT practice, and identified some problems that hinder the process of optimization as well as justification in children.

The growing potential of diagnostic reference levels as a dynamic tool for dose optimization.

Diagnostic Reference Levels (DRLs) is an important tool that can improve radiation safety in medical imaging. However, there are certain aspects that need improvement and several obstacles that should be overcome before DRLs are fully implemented in practice. It is the authors belief that DRLs should be a dynamic tool that follows the development of clinical practice and technology advances. The establishment of adult and paediatric DRLs based on clinical indications should be considered as a priority. A common methodology and terminology is needed to allow for their clinical use. Dose monitoring systems can improve and accelerate the establishment, update and use of DRLs. However, certain steps need to be taken for proper collection. organization and analysis of big data. Availability of clinically qualified medical physicists in medical imaging departments, awareness on the importance of dose optimization and proper cooperation of relevant stakeholders are important prerequisites for the successful establishment and use of DRLs.

An international survey of imaging practices in radiotherapy.

Improvements in delivery of radiation dose to target tissues in radiotherapy have increased the need for better image quality and led to a higher frequency of imaging patients. Imaging for treatment planning extends to function and motion assessment and devices are incorporated into medical linear accelerators (linacs) so that regions of tissue can be imaged at time of treatment delivery to ensure dose distributions are delivered as accurately as possible. A survey of imaging in 97 radiotherapy centres in nine countries on six continents has been undertaken with an on-line questionnaire administered through the International Commission on Radiological Protection mentorship programme to provide a snapshot of imaging practices. Responses show that all centres use CT for planning treatments and many utilise additional information from magnetic resonance imaging and positron emission tomography scans. Most centres have kV cone beam CT attached to at least some linacs and use this for the majority of treatment fractions. The imaging options available declined with the human development index (HDI) of the country, and the frequency of imaging during treatment depended more on country than treatment site with countries having lower HDIs imaging less frequently. The country with the lowest HDI had few kV imaging facilities and relied on MV planar imaging intermittently during treatment. Imaging protocols supplied by vendors are used in most centres and under half adapt exposure conditions to individual patients. Recording of patient doses, a knowledge of which is important in optimisation of imaging protocols, was limited primarily to European countries.

Assessment of performance of a new digital image intensifier fluoroscopy system.

The aim of this study is to assess the physical properties of a recently installed digital fluoroscopy unit, Axiom Iconos R200 unit (Siemens, Germany), including image quality and patient dose. Image quality parameters and patient doses were measured at various fields of view (FOV) and frame rates. The entrance surface dose rate (ESDR) was measured using standard 30 x 30 cm2 polymethylmethacrylate (PMMA) phantom with different thicknesses. The ESDR was measured using a 20 cm PMMA and largest FOV ranged from 1.1 to 8.2 mGy min(-1) for different frame rates available. The low-contrast sensitivity varied from 1.8 to 6.6%, as the limiting spatial resolution changes from 1.25 to 2.24 ln mm(-1) for the different magnifications, frame rates and phantom thicknesses. This study shows the weak points of the standard quality control protocols. The additional image quality and dose assessments revealed the existing potential for optimisation of the system.

Patient dosimetry in paediatric diagnostic radiology.

A study of patient exposure in paediatric diagnostic radiology was conducted in three dedicated paediatric departments. The entrance surface dose was assessed by three methods: direct measurement by thermoluminescent dosemeters, calculation from the dose-area product and from the tube output. The results obtained by the these methods were compared, proving that all of them are applicable for the assessment of paediatric doses. Subsequently, the accumulated data were compared with the mean values from other similar studies and to the reference dose levels set by the Commission of European Communities, which clearly demonstrated the need for further investigation of the paediatric dose levels in Bulgaria and for optimisation of the radiological practice.

An estimate of the influence of the measurement procedure on patient and phantom doses in breast imaging.

This work is aimed to study the variability of dosimetry results owing to various measurement methodologies for breast dosimetry. This is performed in the frame of the development of a national protocol for breast dosimetry. Doses for standard phantom and group of patients were calculated for two mammography systems from the tube output measured with a calibrated ionisation chamber. The backscatter from the phantom under the chamber contributes to an increase in dosimeter readings of approximately 0.8-1.5%, whereas the proximity of the compression plate to the chamber causes increase in the measured air kerma value by 6.5-7%. High value layer (HVL) measured with solid-state detector without corrections for energy dependence was 17% higher than the one measured with ionisation chamber, which causes corresponding overestimation of average glandular dose (AGD). The use of conversion factors based on typical but not measured HVL values leads to 3.5-5.6% overestimation of AGD. Although the sources of uncertainty were taken into account, the difference between the phantom and patient doses was 24%. Some practical recommendations to be included in the national dosimetry protocol are summarised.

European survey of dental X-ray equipment.

The implementation of an X-ray Quality Assurance (QA) program is a legal requirement in Europe as stipulated in the EU Council Directive 97/43/EURATOM (MED). A review of the literature has identified that European countries are performing some level of QA testing of their dental X-ray equipment, although the type and level to which testing is performed can differ. The European SENTINEL co-ordination action proposed to collate a survey of equipment data for both conventional and digital dental X-ray installations among the SENTINEL partners. The European QA results confirm that systems can be operated below tolerance, and in some cases significantly so, while still in clinical use. This can occur despite servicing of equipment. The results have emphasised the fact that there is a requirement for the medical physics/engineering professions to become more closely involved in the management of dental radiology equipment. This also includes their involvement in the development and delivery of appropriate training courses for dentists and suppliers of dental radiology equipment.

Survey on performance assessment of cardiac angiography systems.

Advances in imaging technology have facilitated the development of increasingly complex interventional cardiac equipment. Consequently, there is a need for definitive equipment requirements. The aim of the study is to assess the performances of different cardiac angiographic systems. A questionnaire was sent to centres participating in SENTINEL Project to collect dosimetry data (typical entrance dose rate in fluoroscopy and imaging mode), image quality evaluations (low and high contrast resolutions) and KAP calibration factors. Results from this survey could contribute to the explanation of patient dose variability in angiographic cardiac procedures and to derive reference levels for cardiac angiographic equipment performance parameters.

Quality control measurements for fluoroscopy systems in eight countries participating in the SENTINEL EU coordination action.

Quality control (QC) is becoming increasingly important in relation to the introduction of digital medical imaging systems using X rays. It was, therefore, decided to organise and perform a trial on image quality and physical measurements. The SENTINEL toolkit for QC measurements of fluoroscopy systems containing equipment and instructions for their use in the assessment of dose and image quality circulated among participants in the trial. The participants reported on their results. In the present contribution, the impact of the trial on the selected protocols is presented. The Medical Physics and Bioengineering protocol appeared to be useful for QC, and also for digital systems. The protocol needs an additional section, or an addition to each section, to state compliance with the requirements. The circular cross-sections of the Leeds test objects need adaptation for rectangular flat panel detector (FPD) systems. Only one participant was able to perform the monitor test using MoniQA. This is due to the fact that assistance is required from the suppliers of the X-ray systems. This problem needs to be solved to apply MoniQA in practice.

Reference levels at European level for cardiac interventional procedures.

In interventional cardiology, a wide variation in patient dose for the same type of procedure has been recognised by different studies. Variation is almost due to procedure complexity, equipment performance, procedure protocol and operator skill. The SENTINEL consortium has performed a survey in nine european centres collecting information on near 2000 procedures, and a new set of reference levels (RLs) for coronary angiography and angioplasty and diagnostic electrophysiology has been assessed for air kerma-area product: 45, 85 and 35 Gy cm2, effective dose: 8, 15 and 6 mSv, cumulative dose at interventional reference point: 650 and 1500 mGy, fluoroscopy time: 6.5, 15.5 and 21 min and cine frames: 700 and 1000 images, respectively. Because equipment performance and set-up are the factors contributing to patient dose variability, entrance surface air kerma for fluoroscopy, 13 mGy min(-1), and image acquisition, 0.10 mGy per frame, have also been proposed in the set of RLs.

Staff dosimetry in interventional cardiology: survey on methods and level of exposure.

In interventional cardiac procedures, staff operates near the patient in a non-uniformly scattered radiation field. Consequently, workers may receive, over a period, relatively high radiation doses. The measurement of individual doses to personnel becomes critical due to the use of protective devices and, as a consequence of the large number of methods proposed to assess the effective dose, great variability in monitoring programmes is expected among European countries. SENTINEL consortium has conducted a survey on staff dosimetry methods and on the level of staff exposure in 12 European cardiac centres demonstrating the urgent need to harmonise dosimetry methods. From the dosimetry survey, constraint annual effective dose of 1.4 mSv and Hp(0.07) over the protective apron of 14 mSv are proposed for the optimisation the exposure the most-exposed operator.

Patient dose in interventional radiology: a European survey.

Patient doses for a few common fluoroscopy-guided procedures in interventional radiology (IR) (excluding cardiology) were collected from a few radiological departments in 13 European countries. The major aim was to evaluate patient doses for the basis of the reference levels. In total, data for 20 procedures for about 1300 patients were collected. There were many-fold variations in the number of IR equipment and procedures per population, in the entrance dose rates, and in the patient dose data (total dose area product or DAP, fluoroscopy time and number of frames). There was no clear correlation between the total DAP and entrance dose rate, or between the total DAP and fluoroscopy time, indicating that a number of parameters affect the differences. Because of the limited number of patients, preliminary reference levels were proposed only for a few procedures. There is a need to improve the optimisation of IR procedures and their definitions and grouping, in order to account for their different complexities.