Review and optimisation of foot radiography technique.

INTRODUCTION: Radiography is an important tool in the diagnosis of trauma and diseases of the foot. Consistent image quality and anatomical appearances are essential to ensure that images are interpreted correctly and this study aims to evaluate current technique and use anthropomorphical phantoms in order to investigate the most optimal radiographic technique. METHODS: A two part study was conducted. An electronic survey was administered in order to ascertain the current radiographic technique utilised within the United Kingdom (UK) National Health Service (NHS) and compare this with techniques published within radiographic positioning textbooks in common use within the UK. A phantom experiment also sought to identify the most appropriate angulation of the central beam to employ in order to optimally visualise the anatomy for standard non-trauma radiography of the foot. A relative visual grading analysis technique was used to assess radiographic quality. RESULTS: The electronic survey was completed by 38% of departments (n = 69/182) and demonstrated wide inconsistencies in projections, centring points and beam angulations employed across the NHS. The most commonly employed techniques no longer match the majority of positions described in textbooks. The phantom experiment modelled the ability to accurately visualise anatomy with a variation of the central beam angulation. The results demonstrated that the most commonly described textbook techniques remain the most optimal for accurately visualising the anatomy of the foot. CONCLUSION: This study has validated the radiographic techniques of the foot described in many of the key texts, however self-reported current practice has diverged from this textbook description. IMPLICATIONS FOR PRACTICE: Reinforcement of fundamental principles will benefit the patient with increased image quality, improved diagnosis and improved consistency of images, particularly when patient care is transferred between centres.

Variation in pelvic radiography practice: Why can we not standardise image acquisition techniques?

INTRODUCTION: Pelvic radiographs remain an essential investigation in orthopaedic practice. Although it is recognised that acquisition techniques can affect image appearances and measurement accuracy, it remains unclear what variation in practice exists and what impact this could have on decision making. METHOD: This was a cross sectional survey of UK radiology departments utilising an electronic tool. An introductory letter and link was distributed. Responses were received from 69 unique hospital sites within the specified timeframe, a response rate of 37.9%. RESULTS: There was no consistent technique for the positioning of patients for pelvic radiographs. The distance varied between 90 and 115 cm and 10 different centering points were described. In relation to leg position, the feet are usually internally rotated (65 of 69 [94.2%]). Only 1 teaching hospital (1 of 69 [1.4%]) uses a weight-bearing position as standard. Orthopaedic calibration devices were not in routine use, with only 21 using on pelvic x-rays (30.4%). Further, the type of device and application criteria were inconsistent. CONCLUSIONS: To our knowledge this is the first study to directly compare radiographic positioning across hospital sites. Our data demonstrated marked variation in technique for pelvis radiographs with associated implications for clinical decision making. Research is required to determine the standard technique and quality outcome measures to provide confidence in diagnostic interpretation particularly for serial radiographs.

Impact of body part thickness on AP pelvis radiographic image quality and effective dose.

INTRODUCTION: Within medical imaging variations in patient size can generate challenges, especially when selecting appropriate acquisition parameters. This experiment sought to evaluate the impact of increasing body part thickness on image quality (IQ) and effective dose (E) and identify optimum exposure parameters. METHODS: An anthropomorphic pelvis phantom was imaged with additional layers (1-15 cm) of animal fat as a proxy for increasing body thickness. Acquisitions used the automatic exposure control (AEC), 100 cm source to image distance (SID) and a range of tube potentials (70-110 kVp). IQ was evaluated physically and perceptually. E was estimated using PCXMC software. RESULTS: For all tube potentials, signal to noise ratio (SNR) and contrast to noise ratio (CNR) deceased as body part thickness increased. 70 kVp produced the highest SNR (46.6-22.6); CNR (42.8-17.6). Visual grading showed that the highest IQ scores were achieved using 70 and 75 kVp. As thickness increases, E increased exponentially (r = 0.96; p < 0.001). Correlations were found between visual and physical IQ (SNR r = 0.97, p < 0.001; CNR r = 0.98, p < 0.001). CONCLUSION: To achieve an optimal IQ across the range of thicknesses, lower kVp settings were most effective. This is at variance with professional practice as there is a tendency for radiographers to increase kVp as thickness increases. Dose reductions were experienced at higher kVp settings and are a valid method for optimisation when imaging larger patients.