Criteria and suspension levels in diagnostic radiology.

The EC (European Council) Directive on radiation protection of patients requires that criteria for acceptability of equipment in diagnostic radiology, nuclear medicine and radiotherapy be established throughout the member states. This study reviews the background to this requirement and to its implementation in practice. It notes and considers parallel requirements in the EC medical devices directive and International Electrotechnical Commission standards that it is also important to consider and that both sets of requirements should ideally be harmonised due to the global nature of the equipment industry. The study further reviews the types of criteria that can be well applied for the above purposes, and defines qualitative criteria and suspension levels suitable for application. Both are defined and relationships with other acceptance processes are considered (including acceptance testing at the time of purchase, commissioning and the issue of second-hand equipment). Suspension levels are divided into four types, A, B, C and D, depending on the quality of evidence and consensus they are based on. Exceptional situations involving, for example, new or rapidly evolving technology are also considered. The publication and paper focuses on the role of the holder of the equipment and related staff, particularly the medical physics expert and the practitioner. Advice on how the criteria should be created and implemented is provided for these groups and how this might be coordinated with the supplier. Additional advice on the role of the regulator is provided.

Development of acceptability criteria in mammography.

Quality assurance protocols and standards of performance for X-ray mammography equipment are probably the most developed of any in the area of diagnostic radiology, due to the exacting demands on image quality required in population-based breast cancer screening programmes. Both qualitative and quantitative acceptability criteria have been published for X-ray mammography by considering the image quality needed clinically in screening programmes. Consequently, the task of developing a consensus for acceptability criteria appears to be relatively easy at first glance. However, there are two contentious issues that must be considered; the first is whether standards based on breast cancer screening can be transposed to equipment used for women referred for imaging with breast symptoms. The second relates to the use of image-quality assessment based upon the observation of details in test phantoms. In respect of the former, there was general agreement that only one set of acceptability criteria should apply to mammographic X-ray equipment. With regard to image-quality assessment, the weakness of the observer-based methods was recognised and a consensus position developed. This paper describes the development of a consensus on acceptability criteria and proposes both qualitative and quantitative criteria for use on all mammographic equipment. Some test approaches and criteria for image displays, in particular, were omitted from the document as concerns about their robustness emerged during the consultation phases of the revision. Clearly, further scientific work is needed in these areas.

The revision of RP 91 on criteria for acceptability of radiological (including radiotherapy) and nuclear medicine installations.

In 1997 the European Commission published Radiation Protection 91: 'Criteria for acceptability of radiological (including radiotherapy) and nuclear medicine installations'. This document specified the minimum criteria for acceptability. It has been used to this effect in legislation, codes of practice and by individual professionals. In a single document, it defined a level of performance at which remedial action was required. The document specified a series of parameters which characterised equipment performance and acceptable levels of performance. In its time it proved to be a useful document which was applied in member states to various degrees. Since the publication of Report 91 in 1997, a series of weaknesses emerged over time. Development of new radiological systems and technologies, as well as improvements in traditional technologies, has created circumstances where the acceptability criteria were in need of review. These weaknesses were recognised by the European Commission and a tender for its revision was issued. The criteria were developed by a team drawn from a broad range of backgrounds including hospitals, industry, government bodies, regulators and standardisation organisations. Representatives were mainly from Europe, but individuals from the American Association of Physicists in Medicine and International Atomic Energy Agency were included in the drafting process. This study describes the process employed in developing the revised document and the consultation process involved. One of the major difficulties the revision team encountered was related to an understanding of the actual meaning of the EC Directive. The view taken by the revision team was that Article 8, paragraph 3 places responsibilities on both the holders of radiological equipment and competent authorities. The acceptability criteria have been produced consistent with the European Commission's Medical Exposures Directive, which requires that patient exposures are optimised and justified.

Cervical cancer incidence in young women: a historical and geographic controlled UK regional population study.

BACKGROUND: The commencing age of cervical screening in England was raised from 20 to 25 years in 2004. Cervical cancer incidence in young women of England is increasing. It is not clear if this is due to either greater exposure to population risk factors or reduced cervical screening. METHODS: We measured if the relative risk of cervical cancer in younger women (20-29 years) of the north-east of England (NE) differed to that of women aged 30yrs and above since 2004. We also measured average annual percentage change (AAPC) in the 3 yr moving average incidence for all age-groups. Regional screening coverage rate and population risk factors were reviewed. Comparisons were made with Wales where screening continues to commence from the age of 20yrs. RESULTS: Cervical cancer incidence in women aged 20-29 increased annually by an average of 10.3% between 2000 and 2009. The rise in women aged 30-39 was less steep (3.5%/year) but no significant rise was observed in women aged 40-49. Socioeconomic factors remained stable or improved during the time period except for the incidence of chlamydia, herpes simplex and in particular, genital warts, which increased significantly in young women. Data from Wales show similar results. CONCLUSION: The incidence of cervical cancers in young women of the NE is increasing. The rise in incidence is unrelated to the change in screening policy in 2004. Close monitoring of incidence in young women and a greater attempt to reverse the current decline in screening coverage of women aged 25-29 years are recommended.

A review of patient dose and optimisation methods in adult and paediatric CT scanning.

An increasing number of publications and international reports on computed tomography (CT) have addressed important issues on optimised imaging practice and patient dose. This is partially due to recent technological developments as well as to the striking rise in the number of CT scans being requested. CT imaging has extended its role to newer applications, such as cardiac CT, CT colonography, angiography and urology. The proportion of paediatric patients undergoing CT scans has also increased. The published scientific literature was reviewed to collect information regarding effective dose levels during the most common CT examinations in adults and paediatrics. Large dose variations were observed (up to 32-fold) with some individual sites exceeding the recommended dose reference levels, indicating a large potential to reduce dose. Current estimates on radiation-related cancer risks are alarming. CT doses account for about 70% of collective dose in the UK and are amongst the highest in diagnostic radiology, however the majority of physicians underestimate the risk, demonstrating a decreased level of awareness. Exposure parameters are not always adjusted appropriately to the clinical question or to patient size, especially for children. Dose reduction techniques, such as tube-current modulation, low-tube voltage protocols, prospective echocardiography-triggered coronary angiography and iterative reconstruction algorithms can substantially decrease doses. An overview of optimisation studies is provided. The justification principle is discussed along with tools that assist clinicians in the decision-making process. There is the potential to eliminate clinically non-indicated CT scans by replacing them with alternative examinations especially for children or patients receiving multiple CT scans.

Histological recurrence and depth of loop treatment of the cervix in women of reproductive age: incomplete excision versus adverse pregnancy outcome.

OBJECTIVE: Recent meta-analyses have shown that loop treatment of the cervix of > 10 mm depth may be associated with adverse outcomes in future pregnancies. The aim of this study is to assess the rate of incomplete excision and recurrent disease in relation to depth of excision in women of reproductive age undergoing loop treatment. DESIGN: Observational cohort study. SETTING: Colposcopy Clinic, Northern Gynaecological Oncology Centre, Gateshead, UK. POPULATION: In all, 1558 women undergoing loop treatment for high-grade cervical intraepithelial neoplasia (HGCIN) between 1998 and 2003. METHODS: Women were followed up until 2008. Recurrence was analysed using Kaplan-Meier plots. OUTCOME MEASURES: Incomplete excision rates and recurrence rates. Recurrence was defined as post-treatment disease with high-grade histology. Any dyskaryotic cytology on follow-up was also documented. RESULTS: Recurrent high-grade disease on histology was found in 57/1558 (3.7%) women. In women ≤ 35 years old, despite a greater rate of incomplete excision at the endocervical margin at loop depths < 10 mm compared with ≥ 10 mm (24.4% versus 13.3%, P < 0.01), the recurrence rate was similar between the two groups (4.3% versus 3.4%, log-rank, P = 0.52). In contrast, a loop depth < 10 mm was associated with a higher disease recurrence rate (7.5% versus 3.0%, log-rank, P = 0.05) in women > 35 years. CONCLUSION: In women of reproductive age requiring treatment for HGCIN, colposcopists performing loop excision should aim for < 10 mm depth. This provides adequate treatment for HGCIN and minimises the potential risk of adverse outcomes in future pregnancies.

A clinical audit programme for diagnostic radiology: the approach adopted by the International Atomic Energy Agency.

The International Atomic Energy Agency (IAEA) has a mandate to assist member states in areas of human health and particularly in the use of radiation for diagnosis and treatment. Clinical audit is seen as an essential tool to assist in assuring the quality of radiation medicine, particularly in the instance of multidisciplinary audit of diagnostic radiology. Consequently, an external clinical audit programme has been developed by the IAEA to examine the structure and processes existent at a clinical site, with the basic objectives of: (1) improvement in the quality of patient care; (2) promotion of the effective use of resources; (3) enhancement of the provision and organisation of clinical services; (4) further professional education and training. These objectives apply in four general areas of service delivery, namely quality management and infrastructure, patient procedures, technical procedures and education, training and research. In the IAEA approach, the audit process is initiated by a request from the centre seeking the audit. A three-member team, comprising a radiologist, medical physicist and radiographer, subsequently undertakes a 5-d audit visit to the clinical site to perform the audit and write the formal audit report. Preparation for the audit visit is crucial and involves the local clinical centre completing a form, which provides the audit team with information on the clinical centre. While all main aspects of clinical structure and process are examined, particular attention is paid to radiation-related activities as described in the relevant documents such as the IAEA Basic Safety Standards, the Code of Practice for Dosimetry in Diagnostic Radiology and related equipment and quality assurance documentation. It should be stressed, however, that the clinical audit does not have any regulatory function. The main purpose of the IAEA approach to clinical audit is one of promoting quality improvement and learning. This paper describes the background to the clinical audit programme and the IAEA clinical audit protocol.

Histories including number of falls may improve risk prediction for certain non-vertebral fractures in older men.

OBJECTIVE: To determine whether information on number of falls on a falls history screen predicts risk of non-vertebral and hip fracture. METHODS: A cohort of 5995 community-dwelling men aged 65 years and older (mean 73.7) was followed over 7.2 years for incident non-vertebral fractures. Cox proportional hazard models were used to calculate hazard ratios (HRs) (95% CI) for incident fracture comparing a history of one and two or more falls with no falls. Models were adjusted for age, clinic, body mass index, height, femoral neck bone mineral density and whether the participant had a non-trauma fracture after the age of 50. p

Lifestyle predicts falls independent of physical risk factors.

SUMMARY: Many falls occur among older adults with no traditional risk factors. We examined potential independent effects of lifestyle on fall risk. Not smoking and going outdoors frequently or infrequently were independently associated with more falls, indicating lifestyle-related behavioral and environmental risk factors are important causes of falls in older women. INTRODUCTION: Physical and lifestyle risk factors for falls and population attributable risks (PAR) were examined. METHODS: We conducted a 4-year prospective study of 8,378 community-dwelling women (mean age = 71 years, SD = 3) enrolled in the Study of Osteoporotic Fractures. Data on number of falls were self-reported every 4 months. Fall rates were calculated (# falls/woman-years). Poisson regression was used to estimate relative risks (RR). RESULTS: Physical risk factors (p < or = 0.05 for all) included tall height (RR = 0.89 per 5 in.), dizziness (RR = 1.16), fear of falling (RR = 1.20), self-reported health decline (RR = 1.19), difficulty with Instrumental Activities of Daily Living (IADLs) (RR = 1.12, per item), fast usual-paced walking speed (RR = 1.18, per 2 SD), and use of antidepressants (RR = 1.20), benzodiazepines (RR = 1.11), or anticonvulsants (RR = 1.62). Protective physical factors (p < or = 0.05 for all) included good visual acuity (RR = 0.87, per 2 SD) and good balance (RR = 0.85 vs. poor). Lifestyle predicted fewer falls including current smoking (RR = 0.76), going outdoors at least twice weekly but not more than once a day (RR = 0.89 and vs. twice daily). High physical activity was associated with more falls but only among IADL impaired women. Five potentially modifiable physical risk factors had PAR > or = 5%. CONCLUSIONS: Fall interventions addressing modifiable physical risk factors with PAR > or = 5% while considering environmental/behavioral risk factors are indicated.

Ethical concerns arising from screening procedures such as mammography and self-referral.

Shortly after the discovery of X-rays, their harmful effects became apparent. While the harmful effects of ionising radiation were recognised at an early stage, it took some time before a systematic approach to radiation protection evolved. This began with the development of simple rules to reduce the risk of stochastic effects (such as cancer induction) and the occurrence of deterministic injuries (e.g. cataract formation). These rules have evolved into the basic principles of radiation protection, one of which is the concept of justification, which in its simplest form may be taken as doing more benefit than harm. The concept of justification has particular ethical concerns when applied to population screening procedures. These problems are described in this paper with a particular emphasis on the cases of screening and self-referral procedures.

An estimate of the collective dose to the European population from cardiac X-ray procedures.

There have been significant advances in interventional cardiology in recent years that have resulted in an increase in the frequency of both diagnostic and therapeutic X-ray-guided procedures. The number of coronary angiograms, percutaneous transluminal coronary angioplasties (PTCAs) and coronary stent procedures, as well as pacemaker insertions, has increased across Europe. X-ray-guided procedures are used in the treatment of complex cardiac problems and often involve the use of extended fluoroscopy times and the acquisition of a large number of images. There is increasing concern about the dose levels from these procedures, but their impact on the population dose is less well known. In this paper, the number of coronary procedures in various European countries is estimated and the population dose deduced. In addition, the total collective effective doses for cardiac procedures for various European countries have been estimated. In 2006, the estimated average number of coronary angiograms was 5045 per million population, 1511 per million for PTCAs, 836 per million for stents and 918 per million for pacemaker insertions in the 29 countries studied. The estimated population dose from coronary angiograms, pacemaker insertions, PTCA and stent procedures was 27,000 man Sv.

Safety and efficacy for new techniques and imaging using new equipment to support European legislation: an EU coordination action.

The past two decades have witnessed a technologically driven revolution in radiology. At the centre of these developments has been the use of computing. These developments have also been driven by the introduction of new detector and imaging devices in radiology and nuclear medicine, as well as the widespread application of computing techniques to enhance and extract information within the images acquired. Further advances have been introduced into digital practice. These technological developments, however, have not been matched by justification and optimisation studies to ensure that these new imaging devices and techniques are as effective as they might be, or performed at the lowest possible dose. The work programme of the SENTINEL Coordination Action was subdivided into eight work packages: functional performance and standards; efficacy and safety in digital radiology, dentistry and nuclear medicine, cardiology, interventional radiology, population screening/sensitive groups; justification, ethics and efficacy; good practice guidance and training; and project management. The intention of the work programme was to underwrite the safety, efficacy and ethical aspects of digital practice as well as to protect and add value to the equipment used in radiology.

Evaluation of the population dose to the UK population from the National Health Service Breast Screening Programme.

In the United Kingdom National Health Service Breast Screening Programme (NHSBSP), women aged between 50 and 70 y are invited for mammography every 3 y. Screening histories for each woman, over four screening rounds, were analysed. Data from five screening programmes were used to select 57,425 women into the study. Cases were selected on the basis of being between the ages of 50 and 53 at the start of the NHSBSP (i.e. between 1989 and 1992). Assessment of the outcome for each screening round for each woman involved assigning a simple outcome code. Each of the possible pathways through the four screening rounds was analysed. This comprises of 500 possible pathways. This data enabled the following information to be determined: (i) The number of times a woman attended the screening programme. (ii) The number of women referred for assessment at each screening round. This information may be used to deduce the population dose to this group of women averaged over four screening rounds. Patient doses have been monitored since the programme's inception and are typically 4.5 mGy for two-view screening. It is possible to determine the mean glandular dose received by this cohort of women over four screening rounds by multiplying the number of examinations by the mean glandular dose for a typical woman. Allowance has to be made for the number of projections taken at each screening round. Once a woman has been screened, she may be invited back for further assessment if an abnormality is found on her mammogram. A stereotactic attachment is used to determine where to place the biopsy device. Although the dose received during a normal screening mammogram is well known, the dose for a stereotactic procedure and other assessment procedures is less well known, partly because only a small part of the breast is directly irradiated during stereotaxis. However, the woman may have multiple exposures during this stage. A prospective survey of doses was completed to deduce the mean glandular dose at the first assessment stage and during stereotaxis. Numbers of films, including magnification films taken at first-stage assessment were established in the North East of England and Scotland by means of a postal survey. Average total mean glandular dose was deduced using previous survey data for the screening programme and a multiplying factor to allow for magnification film dose. On average 1.6 full field and 0.15 collimated contact films are taken for each woman (with 2.25 and 0.75 mGy film(-1)), 1.0 full field and 0.9 collimated magnification views. The mean magnification film dose to the assessed breast was 5.0 and 1.7 mGy for a collimated magnification film. A survey of 134 women at screening centres in the North East of England was performed to deduce the mean glandular dose from digital stereotaxis which is almost universally used in breast screening. A typical woman received a dose to the assessed breast of 4.5 mGy with a range of 1.3-17 mGy. This data may be used to deduce the total mean glandular dose over four screening rounds including the assessment stages. The estimated mean glandular dose to a typical woman invited to the screening programme is approximately 16 mGy, when allowance for attendance rate and assessment rate over each screening round is made. The mean glandular dose to the population is approximately 4700 Sv y(-1).

Assessment of patient organ dose in CT virtual colonoscopy for bowel cancer screening.

Justification and optimisation form the basic elements for the radiological protection of individuals for medical exposures. Justification includes the assessment of patient organ doses from which radiation risks are deduced. Medical radiation exposures are justified only in the case of a sufficient net benefit. For screening examinations, such as CT virtual colonoscopy, this implies that patient organ doses should be relatively low to minimise the radiation detriment. Image quality should be sufficient to maximise the potential diagnostic benefits. The Medical Exposures Directive places special attention on medical exposures as part of health screening programmes and examinations involving high individual doses to the patient, both of which apply to CT virtual colonoscopy. Technical factors were recorded for a series of patients having virtual colonoscopy on a CT scanner. In addition, the dose-length product was assessed. Patient organ doses were deduced using a CT dose calculation program. The typical effective dose was 7.5 mSv for male patients and 10.2 mSv for female patients. The effective dose is higher for female patients, as some gender-specific organs are irradiated during virtual colonoscopy. Each patient has two series of scans resulting in doses of 15 mSv for male patients and 20 mSv for female patients.

A pilot study exploring the possibility of establishing guidance levels in x-ray directed interventional procedures.

This article summarizes the dosimetric results of an International Atomic Energy Agency coordinated research program to investigate the feasibility of adopting guidance levels for invasive coronary artery procedures. The main study collected clinical data from hospitals located in five countries. A total of 2265 coronary angiograms (CA) and 1844 percutaneous coronary interventions (PCI) were analyzed. Substudies evaluated the dosimetric performance of 14 fluoroscopes, skin dose maps obtained using film, the quality of CA procedures, and the complexity of PCI procedures. Kerma-area product (PKA) guidance levels of 50 and 125 Gy cm2 are suggested for CA and PCI procedures. These levels should be adjusted for the complexity of the procedures performed in a given institution.

Results of a European dose survey for mammography.

For the dose study, a semi-automated method of data collection is used in this study. The participating centres were asked to fill out a spreadsheet with all necessary data and return it. For direct digital (DR) systems, the relevant data available in the DICOM header were used. All data is automatically added to a database and processed. The data were used to calculate the mean glandular dose for every image and for different thicknesses of polymethyl methacrylate phantoms using available conversion factors. Second-degree polynomials were fitted to the patient dose data and a reference dose curve was constructed for a range of thicknesses instead of a dose reference level at a single point. The dose reference curve rises from 1.57 mGy for a thickness of 30 mm to 2.50 mGy for 55 mm and 3.83 mGy for 75 mm. The results show centres that exceed this curve lie only in the lower or higher range of thicknesses and would remain undetected using a dose reference value in a single point. This gives better information to radiographers on where there is room for improvement of the dose levels in their system.

Results of a European survey on patient doses in paediatric radiology.

Paediatric patients represent a very specific group within the radiology department. Compared to adult patients, they are more sensitive to radiation. As they are sometimes submitted to several radiology procedures, dose and image quality should be well balanced. Nowadays, only a few centres specialize in paediatric imaging, and knowledge of paediatric patient doses is, therefore, very scattered. The effect of the introduction of digital technology on paediatric patient doses remains largely undocumented. Data collected in the present survey illustrate that there is a clear need for standardisation in this domain. The proposal of a European diagnostic reference level (DRL) is quite difficult. Preliminary DRLs, based on typically 5-7 radiology centres per examination are proposed. The 'effective dose' may or may not be a very rigorous parameter, but it still remains useful nowadays to calculate a parameter that summarises the possible radiation-induced detriment to these young patients. However, conversion factors for calculation of the effective dose should be harmonised. Future studies should include an image quality evaluation study, using criteria that account for digital equipment. Data collection would be straightforward and could be performed in a systematic and automatic way if DICOM headers of digital images would include appropriate as well as relevant information for the particular case of paediatric examinations.

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.