ICRP special radiation protection issues in interventional radiology, digital and cardiac imaging

The International Commission on Radiological Protection (ICRP) has published two reports giving recommendations dealing with the avoidance of deterministic injuries in interventional radiology and the management of patient dose in digital radiology in 2001 and 2004, respectively. Another document, on radiation protection for cardiologists performing fluoroscopically guided procedures, will be produced during 2005. This paper highlights some of the topics of the published reports, their relevance to European legislation on medical exposures and the importance of radiation protection research in underpinning the ICRP task groups' work in to producing these documents. It is also anticipated that the results, obtained in the cardiology work package of the European research project, will be used in the new document on radiation protection for cardiologists.     

Occupational radiation doses in interventional radiology: simulations

In interventional radiology, occupational radiation doses can be high. Therefore, many authors have established conversion coefficients from the dose-area product data or from the personal dosemeter reading to the effective dose of the radiologist. These conversion coefficients are studied also in this work, with an emphasis on sensitivity of the results to changes in exposure conditions. Comparison to earlier works indicates that, for the exposure conditions examined in this work, all previous models discussed in this work overestimate the effective dose of the radiologist when a lead apron and a thyroid shield are used. Without the thyroid shield, underestimation may occur with some models.     

New ethical issues for radiation protection in diagnostic radiology

The ethical basis for many medical practices has been challenged over the last two decades. Radiology has seen enormous growth during the same period. Many practices and equipment types, now commonplace, did not exist a generation ago. Yet the fundamental ethical basis for these practices has not seen a corresponding level of development. This is possibly an oversight, and may be particularly important given that these innovations have taken place over a period of changing social attitudes. Areas of concern include, for example, issues around justification, consent/authorisation, inadvertent irradiation of the foetus/embryo during pregnancy and the place of paternalism/individual autonomy in the structure of practice. This paper provides the background to a workshop on these issues held in late-2006 and presents a summary of its findings.     

A training syllabus for radiation protection in dental radiology

The EU Council Directive 97/43/EURATOM (MED) states that Member States shall ensure that adequate theoretical and practical training is provided for dental practitioners working with ionising radiation; this also includes the provision of continuing education and training programmes, post-qualification. The area of dental radiology is specifically mentioned in this legally binding document. The Department of Medical Physics and Bioengineering, St James's Hospital, Dublin, is particularly interested in the area of radiation protection training and routinely provides educational courses both at national and international levels. A recent review of their dental radiation protection course was undertaken in conjunction with a number of Principal Dental Surgeons within the Health Service Executive in Ireland. The revised course was delivered to over 200 dental staff members at two separate meetings during 2006. The response from attendees was very positive. It is proposed to extend this course to other dental professionals, working both in the Irish private and public health sectors in the future.     

Transition in occupational radiation exposure monitoring methods in diagnostic and interventional radiology

Radiation exposure monitoring is a traditional keystone of occupational radiation safety measures in medical imaging. The aim of this study was to review the data on occupational exposures in a large central university hospital radiology organisation and propose changes in the radiation worker categories and methods of exposure monitoring. An additional objective was to evaluate the development of electronic personal dosimeters and their potential in the digitised radiology environment. The personal equivalent dose of 267 radiation workers (116 radiologists and 151 radiographers) was monitored using personal dosimeters during the years 2006-2010. Accumulated exposure monitoring results exceeding the registration threshold were observed in the personal dosimeters of 73 workers (59 radiologists' doses ranged from 0.1 to 45.1 mSv; 14 radiographers' doses ranged from 0.1 to 1.3 mSv). The accumulated personal equivalent doses are generally very small, only a few angiography radiologists have doses >10 mSv per 5 y. The typical effective doses are <10 μSv y(-1) and the highest value was 0.3 mSv (single interventional radiologist). A revised categorisation of radiation workers based on the working profile of the radiologist and observed accumulated doses is justified. Occupational monitoring can be implemented mostly with group dosimeters. An active real-time dosimetry system is warranted to support radiation protection strategy where optimisation aspects, including improving working methods, are essential.     

System for personal dosimetry in interventional radiology

The progress made in radiological image processing and transmission is being widely applied in new branches of medicine. The increasing use of interventional radiology in research and clinical practice means that new groups of workers are being exposed to radiation and need to be covered by a system of radiation protection. Interventional radiology requires the operator and assisting personnel to remain close to the patient; typically these procedures require placement of the hands within the radiation field. A system of hand dose monitoring was introduced in Poland in 2000. This system uses ring badges with TL dosemeters. The measurements conducted so far characteristically show an asymmetric right-sided distribution of monthly doses. As expected, operators and their assistants are the most exposed groups of medical personnel. Average hand doses may be very dependent on the type of procedure, personal skills and quality of equipment. The hand doses of these personnel are significant from a radiological protection point of view.     

Double-dosimetry algorithm for workers in interventional radiology

Based on double-dosemeter readings, a conservative effective dose (E) estimation algorithm for lead apron workers in interventional radiology is proposed. Typical radiation conditions for various exposure geometries were simulated using the MCNPX 2.4.0 code. The simulation model consisted of an X-ray source and image intensifier, a patient phantom and a voxelised staff member phantom with lead apron. The effective staff dose and dosemeter readings for several positions of the worker were calculated. The effective dose to a physician, positioned in close proximity to the primary beam, can be estimated within a 10% underestimation margin by E = 1.64 H(p)(10)(thorax,under) + 0.075 H(p)(10)(neck,over). The dose to the eye lens can be estimated by a dosemeter reading at collar level (R(2) = 0.98).     

Usefulness of non-lead aprons in radiation protection for physicians performing interventional procedures

At present, interventional radiology (IVR) tends to involve long procedures (long radiation duration), and physicians are near to the source of scattered radiation. Hence, shielding is critical in protecting physicians from radiation. Protective aprons and additional lead-shielding devices, such as tableside lead drapes, are important means of protecting the physician from scattered radiation. The purpose of this study was to evaluate whether non-lead aprons are effective in protecting physicians from radiation during IVR procedures. In this study, the radiation protection effects of commercially available protective lead and non-lead aprons, when exposed to diagnostic X rays, are compared. The performance of these non-lead and lead aprons was similar for scattered X rays at tube voltages of 60-120 kV. Properly designed non-lead aprons are thus more suitable for physicians because they weigh approximately 20% less than the lead aprons, and are non-toxic.     

Some aspects on radiation protection in conventional and digital radiology in Romania

Since 1965, medical radiation exposure in the population of Romania has been evaluated by the Network of Radiation Hygiene Laboratories of the Ministry of Public Health, including 23 laboratories throughout the whole country; the network is co-ordinated by the Institute of Public Health Bucharest. In Romania, for a population of 22.5 million inhabitants, 465 X-ray examinations were reported during the last survey, the most frequent being chest examination. There was no specific reference to digital radiology. Digital radiology has been introduced only recently in Romania, and only some rough data on the situation can be presented. Siemens AG is now present in Romania with 23 installations, type SIEREGRAPH CF and AXIOM ICONOS. A digital image intensifier technique is used only for fluoroscopy, and radiography is performed using a conventional film/screen combination. The company Philips has nine installations for angiography, model INTEGRIS, and uses a computed radiography technique. Several direct digital radiography MULTISYSTEM SWISSRAY installations (about 40 units) are also available for adult and paediatric examinations. The Council Directive 97/43/EURATOM on health protection of individuals against dangers of ionising radiation in relation to medical exposure was fully transformed into Romanian legislation in 2002.     

Deterministic effects in interventional radiology

Since the development of interventional radiology, the number and complexity of procedures has increased significantly and continues to grow. Interventional radiology procedures offer substantial health care benefits. However, associated with the increasing complexity as well as a lack of quality control programmes and specific training in radiation protection, there is an increase in the occurrence of deterministic effects in both patients and staff. There is a growing literature of case reports describing deterministic effects. A review of some case reports and the response of various international organisations is presented. It is important that workers in interventional radiology are aware of the potential for deterministic effects and the dose threshold for their onset, so that patients can be followed up appropriately.     

Indicators for the finger doses in interventional radiology

Finger doses and other factors have been recorded in order to investigate parameters that could be used to assess the likely level of finger doses of interventional radiologists. A relatively good correlation between finger dose and dose-area product was found regardless of the type of procedure. The correlation between finger dose and screening time was less significant. Very significant correlation between finger doses and the personal dosemeter reading outside the lead apron was found. This strongly suggests that personal dosemeter worn outside the lead apron can serve as a screening device for finger or hand doses to the radiologists. For radiologists, surgeons and cardiologists likely to receive an annual personal dose reading of more than 20 mSv measured outside the lead apron, doses to the hands are likely to be higher than 50 mSv. In these cases, monitoring of finger doses is recommended to establish dose levels.     

Equipment requirements and specification for digital and interventional radiology

During the past decade there has been a substantial growth in digital and interventional radiology. Equipment requirements and specification for digital (interventional) radiology are necessary to facilitate the purchase of proper installations for specific purposes. Inappropriate equipment might lead to increased dose to patients and staff, insufficient image quality and, for interventional radiology, to inefficient procedures and the potential for deterministic effects to occur. The equipment requirements and specifications are of various types. Requirements for dose displays and dose record keeping are dealt with in a separate contribution to this workshop. Detailed information is presented in this contribution on requirements and specifications in relation to ergonomic, dosimetric and image quality aspects.     

Staff dosimetry protocols in interventional radiology

Assessment of effective dose (E) for workers performing interventional radiology is particularly problematic due to the conditions of partial body exposure, so very few estimates of E are found in the literature. Two simple algorithms (the Rosenstein-Webster and the Niklason algorithms) are available that combine the readings of two dosemeters, one worn under the protective apron and one on the neck outside the apron, to estimate E for the range of imaging conditions typical of medical fluoroscopy. The algorithms are reviewed and their suitability for estimating E for personnel performing interventional radiology is analysed by comparison with the most recent experimental data. It can be concluded that the Niklason algorithm's estimates are in better agreement with the experimental assessments of E.     

Quantification of risk-benefit in interventional radiology

The increased use of interventional radiological procedures brings with it an increased risk of cancer induction due to the possible high radiation levels used. This risk must be balanced against any viable alternatives and should take into account the individual risks and benefits. The purpose of this study is to quantify this risk benefit in terms of quality-adjusted life years (QALYs) of a procedure and its alternatives, including the risk due to the radiation. Uterine fibroid embolisation was chosen as a model study with data collected both on the outcomes of procedures in terms of complications and quality of life in the long-term and on radiation dose delivered to the patient. Dosimetry data were obtained from University Hospital Galway. The risk was then calculated using the BEIR VII model of dose-response for low linear energy transfer (LET) radiation. In this case, it was found that the radiological technique has distinct advantages over hysterectomy and myomectomy in terms of QALYs. The increased risk due to radiation from the procedure is small when compared with the overall benefit to the patient. Probability of stochastic effects based on the average dose per procedure carries an attributable risk (fatal and non-fatal cancer and hereditary effects) of 0.4% or a relative risk of 1.09%. The method described here can readily be adapted to other interventional procedures.     

Status of radiation protection in interventional cardiology in four East European countries

Level of staff and patient radiation protection in interventional cardiology in four counties (Bosnia and Herzegovina, Croatia, Montenegro and Serbia) as a part of International Atomic Energy Agency project (RER/9/093) are presented. Patient doses were assessed in terms of air kerma area product (KAP), peak skin dose (PSD) or air kerma at interventional reference point (K(IRP)). Results were available from nine hospitals: 775 patients for KAP, 157 for PSD and 437 for K(IRP). Eight centres reported KAP >100 Gy cm(2) and five centres reported values >200 Gy cm(2). From patients monitored in terms of PSD, 14 (9 %) had PSD >2 Gy and 6 (3 %) patients from those monitored in terms of K(IRP) had value >5 Gy, indicating risk of skin injury. The results indicate need for optimisation and dose monitoring in complex fluoroscopically guided cardiology interventions.     

Physician-received scatter radiation with angiography systems used for interventional radiology: comparison among many X-ray systems

Radiation protection for interventional radiology (IR) physicians is very important. Current IR X-ray systems tend to use flat-panel detectors (FPDs) rather than image intensifiers (IIs). The purpose of this study is to test the hypothesis that there is no difference in physician-received scatter radiation (PRSR) between FPD systems and II systems. This study examined 20 X-ray systems in 15 cardiac catheterisation laboratories (11 used a FPD and 9 used an II). The PRSR with digital cineangiography and fluoroscopy were compared among the 20 X-ray systems using a phantom and a solid-state-detector electronic pocket dosemeter. The maximum PRSR exceeded the minimum PRSR by ~12-fold for cineangiography and ~9-fold for fluoroscopy. For both fluoroscopy and digital cineangiography, the PRSR had a statistically significant positive correlation with the entrance surface dose (fluoroscopy, r = 0.87; cineangiography, r = 0.86). There was no statistically significant difference between the average PRSR of FPDs and IIs during either digital cineangiography or fluoroscopy. There is a wide range of PRSR among the radiography systems evaluated. The PRSR correlated well with the entrance surface dose of the phantom in 20 X-ray units used for IR. Hence, decreasing the dose to the patient will also decrease the dose to staff.     

Patient and staff dosimetry problems in interventional radiology

Interventional radiology has developed into a dynamic part of radiology over the past twenty years, combining diagnostic and therapeutic methods. On the other hand, it is associated with high radiation doses to patient and staff, due to extended fluoroscopy times and the large number of radiographs. Also, occupational exposures from interventional radiology procedures have a tendency to be greater than other radiological examinations. The need for measuring and evaluating patient and staff doses is apparent. However, dose estimations depend on a large number of factors making these procedures very complex. The aim of this study is to review all the different approaches that appear in the literature on this matter, to delineate the different dosimetry protocols that are proposed and to focus on the practical problems that arise when an evaluation or comparison of dosimetry results is attempted.     

Patient dosimetry protocols in digital and interventional radiology

Dosimetry requirements and protocols for performing measurements in digital and interventional radiology are discussed. Calculated entrance surface dose (ESD) is predicted to be of increasing interest in the future, replacing direct measurement with thermoluminescence (TL) dosemeters. The quantities proposed for establishment of reference values for interventional radiology are reviewed briefly, and the methods of collecting the data required for estimation of their values by means of traditional manual and new automatic methods are compared. It is concluded that the manufacturers of X ray units can largely solve the dosimetry problems of interventional radiology in machines with fully digital control systems after they have received sufficient data on patient dosimetry requirements.     

Medical exposures directive: implications for interventional radiology

The new European Directive on Medical Exposures (97/43/EURATOM) specifically mentions 'high dose procedures' among the areas requiring special attention. This is universally interpreted as including the interventional procedures in radiology, cardiology and many of the special procedures involving fluoroscopy in these and related areas. This communication will focus on a definition of interventional procedures. It will examine the equipment, processes and patient and staff risks involved. From this examination it will be evident that new development is rapid in these areas and proceeding at a rate that is well ahead of both supporting research and regulatory framework. It will further note that the level of patient risk which is acceptable may be higher than in many other procedures. Finally it will note where the general provisions of the new Directive must be brought to bear on this new and developing field.