Magnetic Resonance Force Microscopy with a One-Dimensional Resolution of 0.9 Nanometers.

Magnetic resonance force microscopy (MRFM) is a scanning probe technique capable of detecting MRI signals from nanoscale sample volumes, providing a paradigm-changing potential for structural biology and medical research. Thus far, however, experiments have not reached sufficient spatial resolution for retrieving meaningful structural information from samples. In this work, we report MRFM imaging scans demonstrating a resolution of 0.9 nm and a localization precision of 0.6 nm in one dimension. Our progress is enabled by an improved spin excitation protocol furnishing us with sharp spatial control on the MRFM imaging slice, combined with overall advances in instrument stability. From a modeling of the slice function, we expect that our arrangement supports spatial resolutions down to 0.3 nm given sufficient signal-to-noise ratio. Our experiment demonstrates the feasibility of subnanometer MRI and realizes an important milestone toward the three-dimensional imaging of macromolecular structures.

Scottish Bowel Screening Programme colonoscopy quality - scope for improvement?

AIM: The delivery of the Scottish Bowel Screening Programme (SBoSP) is rooted in the provision of a high quality, effective and participant-centred service. Safe and effective colonoscopy forms an integral part of the process. Additional accreditation as part of a multi-faceted programme for participating colonoscopists, as in England, does not exist in Scotland. This study aimed to describe the quality of colonoscopy in the SBoSP and compare this to the English national screening standards. METHODS: Data were collected from the SBoSP between 2007 and 2014. End-points for analysis were caecal intubation, cancer, polyp and adenoma detection, and complications. Overall results were compared with 2012 published English national standards for screening and outcomes from 2006 to 2009. RESULTS: During the study period 53 332 participants attended for colonoscopy. The colonoscopy completion rate was 95.6% overall. The mean cancer detection rate was 7.1%, the polyp detection rate was 45.7% and the adenoma detection rate was 35.5%. The overall complication rate was 0.47%. CONCLUSION: Colonoscopy quality in the SBoSP has exceeded the standard set for screening colonoscopy in England, despite not adopting a multi-faceted programme for screening colonoscopy. However, the overall adenoma detection rate in Scotland was 9.1% lower than that in England which has implications for colonoscopy quality and may have an impact on cancer prevention rates, a key aim of the SBoSP.

ARTIFICIAL INTELLIGENCE AND DEEP LEARNING IN DIAGNOSTIC RADIOLOGY-IS THIS THE NEXT PHASE OF SCIENTIFIC AND TECHNOLOGICAL DEVELOPMENT?

This paper is concerned with the role of science and technology in helping to create change in society. Diagnostic radiology is an example of an activity that has undergone significant change due to such developments, which over the past 40 years have led to a huge increase in the volume of medical imaging data generated. However, these developments have by and large left the human elements of the radiological process (referrer, radiographer and radiologist) intact. Diagnostic radiology has now reached a stage whereby the volume of information generated cannot be fully utilised solely by employing human observers to form clinical opinions, a process that has not changed in over 100 years. In order to address this problem, the potential application of Artificial Intelligence (AI) in the form of Deep Learning (DL) techniques to diagnostic radiology indicates that the next technological development phase may already be underway. The paper outlines the historical development of AI techniques, including Machine Learning and DL Neural Networks and discusses how such developments may affect radiological practice over the coming decades. The ongoing growth in the world market for radiological services is potentially a significant driver for change. The application of AI and DL learning techniques will place quantification of diagnostic outcomes at the heart of performance evaluation and quality standards. The effect this might have on the optimisation process will be discussed and in particular the possible need for automation in order to meet more stringent and standardised performance requirements that might result from these developments. Changes in radiological practices would also impact upon patient protection including the associated scientific support requirements and these are discussed.

On the justification of justification in radiation protection - legal and sociological considerations.

OBJECTIVES: The objectives of the review were to investigate the legal and sociological basis of justification in society in order to fully assess its relevance to radiation protection. The difference between the justification of practices as distinct from the justification of reasons for the justification of individual activities within a practice and the relevance of cost-benefit analysis to this process are key elements. KEY FINDINGS: Justification of practices as a principle of radiation protection is automatically enshrined within the appropriate legislation once it has been enacted. However, the justification of reasons for justification of activities within a practice are subject to many sociological factors, which are often conflicting and indeterminate and can be subject to political, economic and environmental factors that may change over time. This applies especially to new developments where the primary reason for justification is based upon potential but possibly ill-defined future benefits. CONCLUSION: The primary mechanism whereby society develops a collective consensus on the justification of practices lies within a legal framework. This represents the mechanism by which society defines the accepted standards that must be applied for acceptance of a practice. The justification of reasons for justifying activities that form part of a practice has largely been ignored within the framework of radiation protection. IMPLICATIONS FOR PRACTICE: The employment of justification of practices as a fundamental principle of radiation protection should be eliminated since it is already enshrined within the legal framework applicable to applications of ionising radiation. Justification of reasons for pursuing new or modified practices is based upon their perceived benefits to society, which underpins most developments in society.

Cost-risk-benefit analysis in diagnostic radiology with special reference to the application of referral guidelines.

Cost-risk-benefit analysis has been applied to protection of the patient in diagnostic radiology with special reference to the application of referral guidelines. The analysis presented has extended previous work in this field to provide a theoretical framework that encompasses key factors that need to be considered in the optimisation of patient protection from both diagnostic and radiation risks. The fraction of patients whose symptoms do not meet criteria contained in the referral guidelines and, therefore, for whom an X-ray examination is not indicated has been termed the selectivity of the guidelines. Also included are the detriments arising from rejected or repeated examinations as well as the levels of patient dose employed in order to achieve given levels of true and false diagnostic outcomes. A comprehensive framework for optimisation is outlined and its relationship to justification discussed.

THE PSYCHOLOGY OF DECISION MAKING AND ITS RELEVANCE TO RADIATION PROTECTION OF THE PATIENT IN MEDICINE.

An analysis and review of the fundamental psychological basis of decision making has been undertaken in respect of radiation protection of the patient in medicine. Both clinical and scientific aspects of patient protection have been considered. Every stage of the clinical process of radiological examinations, from referral through to diagnostic outcome, has been shown to be subject to proven psychological effects including biases, framing, anchoring and prospect theory, which deals with perceived gains and losses. Such factors also influence the scientific aspects of radiation protection of the patient. Justification for the use of single dose reference level (DRL) values has employed framing with substitution or manipulation by accessibility in order to promote their usefulness. The use of DRLs as presently proposed constrains a diverse patient population to a reference or representative person. This approach is shown to represent a public health initiative that largely ignores the ethical basis of patient protection inherent in the Hippocratic Oath.

A REVIEW OF THE FUNDAMENTAL PRINCIPLES OF RADIATION PROTECTION WHEN APPLIED TO THE PATIENT IN DIAGNOSTIC RADIOLOGY.

A review of the role and relevance of the principles of radiation protection of the patient in diagnostic radiology as specified by ICRP has been undertaken when diagnostic risks arising from an examination are taken into account. The increase in population doses arising from diagnostic radiology over the past 20 years has been due to the widespread application of higher dose CT examinations that provide significantly more clinical information. Consequently, diagnostic risks as well as radiation risks need to be considered within the patient radiation protection framework. Justification and optimisation are discussed and the limitations imposed on patient protection by employing only a radiation risk framework is highlighted. The example of radiation protection of the patient in breast screening programmes employing mammography is used to highlight the importance of defined diagnostic outcomes in any effective radiation protection strategy.

Membrane-based torque magnetometer: Enhanced sensitivity by optical readout of the membrane displacement.

The design and realization of a torque magnetometer is reported that reads the deflection of a membrane by optical interferometry. The compact instrument allows for low-temperature measurements of tiny crystals less than a microgram with a significant improvement in sensitivity, signal-to-noise ratio as well as data acquisition time compared with conventional magnetometry and offers an enormous potential for further improvements and future applications in different fields. Magnetic measurements on single-molecule magnets demonstrate the applicability of the membrane-based torque magnetometer.

Patient dose measurements in radiological practices.

Internationally agreed standards for radiation measurements applied to medicine underpin the application of scientific methods to both therapeutic and diagnostic radiological practices. Equally it is recommended that these standards should underpin radiation measurements within the fields of nuclear energy and industrial applications of ionizing radiations. Such measurements should also apply to all exposed groups: patients, workers and members of the general public. It would appear that the underlying philosophy as well as measurement methods, including units, employed in the therapeutic and diagnostic domains have developed separately and independently over the past 30 years. Similarly, although radiological imaging methods are fundamental to both domains, a similar situation appears to apply to the assessment of image quality. This letter attempts to highlight the present situation regarding the role and relevance of dosimetric methods applied in both therapeutic and diagnostic radiological practices. In particular the present situation is discussed in relation to the primary objectives of the International Commission on Radiological Units and Measurements (ICRU). Scope for harmonization and unification of scientific methods applied in therapy and diagnosis is highlighted.

COST-RISK-BENEFIT ANALYSIS IN DIAGNOSTIC RADIOLOGY: A THEORETICAL AND ECONOMIC BASIS FOR RADIATION PROTECTION OF THE PATIENT.

In 1973, International Commission on Radiological Protection Publication 22 recommended that the acceptability of radiation exposure levels for a given activity should be determined by a process of cost-benefit analysis. It was felt that this approach could be used to underpin both the principle of ALARA as well for justification purposes. The net benefit, B, of an operation involving irradiation was regarded as equal to the difference between its gross benefit, V, and the sum of three components; the basic production cost associated with the operation, P; the cost of achieving the selected level of protection, X; and the cost Y of the detriment involved in the operation: [Formula: see text] This article presents a theoretical cost-risk-benefit analysis that is applicable to the diagnostic accuracy (Levels 1 and 2) of the hierarchical efficacy model presented by National Council on Radiation Protection and Measurements in 1992. This enables the costs of an examination to be related to the sensitivity and specificity of an X-ray examination within a defined clinical problem setting and introduces both false-positive/false-negative diagnostic outcomes into the patient radiation protection framework.

Central dose data management and analysis in IT-driven radiation protection strategies.

The applications of information technology in health care are now widespread and continue to grow. Medical imaging is at the forefront of this revolution and the introduction of digital detection methods to replace film is now addressing the diagnostic X-ray market, the most routinely employed imaging modality. The introduction of picture archiving and communication systems, hospital and radiology information systems is well underway, and the integration of radiation protection initiatives into these developments is desirable. In north-west UK, a project aimed at developing and implementing IT-driven radiation protection strategies has been underway for the past 10 y. Such strategies are geared towards the support of European Commission patient dose directive 97/43 EURATOM, in particular the need to implement clinical audit, patient dose audit and to establish dose reference levels. This paper demonstrates the national and local requirements for establishing a central dose data management system for use in radiation protection strategies. In particular, such a system can help develop and support the role of a medical physics expert in optimisation. The scientific requirements for such an approach are presented in this paper, and a prototype system is described. Preliminary results obtained with the central data management facility are also presented and the implication for analysing multiple site dose data in optimisation strategies for digital radiographic technology is highlighted.

Evaluation and testing of computed radiography systems.

The implementation of film replacement digital radiographic imaging systems throughout Europe is now gathering momentum. Such systems create the foundations for totally digital departments of radiology, since radiographic examinations constitute the most prevalent modality. Although this type of development will lead to improvements in the delivery and management of radiological service, such widespread implementation of new technology must be carefully monitored. The implementation of effective QA tests on installation, at periodic intervals and as part of a routine programme will aid this process. This paper presents the results of commissioning tests undertaken on a number of computed radiography imaging systems provided by different manufacturers. The aim of these tests was not only to provide baseline performance measurements against which subsequent measurements can be compared but also to explore any differences in performance, which might exist between different units. Results of measurements will be presented for (1) monitor and laser printer set-up; (2) imaging plates, including sensitivity, consistency and uniformity; (3) resolution and contrast detectability; and (4) signal and noise performance. Results from the latter are analysed in relationship with both system and quantum noise components.

RADIUS--closing the circle on the assessment of imaging performance.

The RADIUS (Radiological Imaging Unification Strategy) project addresses the assessment of image quality in terms of both physical and clinically relevant measures. The aim is to unify our understanding of both types of measure as well as the numerous underlying factors that play a key role in the assessments of imaging performance. In this way it is expected to provide a solid basis for the improvement in radiological safety management, where not only radiation risks are considered but also diagnostic risks of incorrect clinical outcomes (i.e. false positive/false negative). The project has applied a variety of relevant experimental and theoretical methods to this problem, which is generic to medical imaging as a whole. Digital radiography of the chest and the breast has been employed as the clinical imaging domain vehicles for the study. The project addressed the problem from the following directions: role and relevance of pathology, human observer studies including receiver operating characteristics, image quality criteria analysis, structural noise analysis, physical measurements on clinical images, physical measurements on imaging system, modelling of imaging system, modelling of visual processes, modelling of doses delivered and IT-based scientific support strategies. This paper presents an overview of the main outcomes from this project and highlights how the research outcomes actually apply to the real world. In particular, attention will be focused on new and original findings and methods and techniques that have been developed within the framework of the project. The relevance of the project's outcomes to future European research will also be presented.

Establishment of a comprehensive set of regional DRLs for CT by means of electronic X-ray examination records.

The International Commission on Radiological Protection (ICRP) has indicated that the diagnostic reference level (DRL) has the optimisation of protection as its objective for diagnostic and interventional procedures [International Commission on Radiological Protection. Protection against ionising radiation from external sources: ICRP Report 105 (2007)]. An important aim of this paper was to demonstrate a straightforward and cost-effective mechanism for undertaking patient dose audits that can be employed in the production of local and regional DRLs for use by medical physics experts in the provision of scientific support services to diagnostic radiology. The process developed employs electronic X-ray examination records obtained from multiple hospital sites transferred to a central processing and reporting facility. Results of a large-scale audit of patient doses resulting from CT examinations are presented. Doses are expressed in terms of dose length product (DLP) and were collected by remotely accessing electronic examination records held in hospital radiology information systems. Data were collected from 18 hospital sites involving up to 123 different types of examinations covering an ∼18-month period from July 2011 to December 2012. In total, 177 000 CT examination records were collected. Values have been validated against equivalent records obtained from digital imaging and communications in medicine (DICOM) header data and found to be in excellent statistical agreement. Extremely large variations in DLP values were noted for many examinations when data for all scanners were pooled. Results are discussed in relation to other surveys and differences highlighted in terms of the variations in methodologies employed and the numbers of examination records investigated. A mechanism for establishing DRLs is proposed, which could help to unify mechanisms for establishing DRLs for CT examinations.

Noise transfer in screen-film subtraction radiography.

The transfer of noise through the stages of a screen-film subtraction process was investigated. In particular the effect of measuring aperture size and film density on the measured noise granularity was studied. The relative contributions of quantum noise and film grain noise were found to depend on both aperture and density. Noise measurements are presented for a medium speed screen-film combination and also for a low noise alpha 16-Kodak Industrex C system. The effect of grain mottle and film blur on noise transfer through the multiple print process employed in subtraction radiography is demonstrated.

Contrast-detail assessment of computed tomography scanners.

The design and construction of contrast-detail detectability phantoms for the assessment of the imaging performance of CT scanners are described. These phantoms have been employed to undertake a series of measurements on a number of different machines. The results are expressed in terms of object contrast which is consistent with the conventional definition of radiological contrast. For one particular scanner, the imaging performance of a number of image reconstruction and post-processing filters has been investigated. The results indicate that there was no observed energy dependence of contrast-detail detectability once differences in technique factors and attenuation were taken into account. A similar conclusion was drawn from the results of a set of measurements made to examine the effect on detectability of additional filtration.

Noise and contrast detection in computed tomography images.

A discrete representation of the reconstruction process is used in an analysis of noise in computed tomography (CT) images. This model is consistent with the method of data collection in actual machines. An expression is derived which predicts the variance on the measured linear attenuation coefficient of a single pixel in an image. The dependence of the variance on various CT scanner design parameters such as pixel size, slice width, scan time, number of detectors, etc., is then described. The variation of noise with sampling area is theoretically explained. These predictions are in good agreement with a set of experimental measurements made on a range of CT scanners. The equivalent sampling aperture of the CT process is determined and the effect of the reconstruction filter on the variance of the linear attenuation coefficient is also noted, in particular, the choice and its consequences for reconstructed images and noise behaviour. The theory has been extended to include contrast detail behaviour, and these predictions compare favourably with experimental measurements. The theory predicts that image smoothing will have little effect on the contrast-detail detectability behaviour of reconstructed images.

A suggested theory of the conventional tomographic imaging process.

An attempt is made to re-examine the well established theoretical basis of conventional tomography in the light of more detailed techniques being applied elsewhere in image analysis. Transfer function theory has been used to quantify the amount of edge detail reproduced by this process and the information in a tomogram is investigated in terms of edge detail associated with well resolved (unblurred) detail and also that associated with particular anatomical layers within the tomographed object, the theory has been used to define a cut plane thickness. A variety of different tube movements have been considered and calculated values of cut plane thickness are compared with those predicted by a simple geometric model. Besides the blurring associated with the tube movement the effect of x-ray focal spot, film-screen combination and also visual response of the observer have been included and their importance in the definition of cut plane thickness highlighted. One advantage of this approach appears to be the facility to quantify the performance of different tomographic tube movements and highlight the role of tomographic detail reproduced from body sections well removed from the cut plane.