Optimising image quality and radiation dose for neonatal incubator imaging

INTRODUCTION

Neonates often require imaging within incubators however limited evidence exists as to the optimal method and acquisition parameters to achieve these examinations. This study aims to standardise and optimise neonatal chest radiography within incubators.

METHODS

A neonatal anthropomorphic phantom was imaged on two different incubators under controlled conditions using a DR system. Exposure factors, SID and placement of image receptor (direct v tray) were explored whilst keeping all other parameters consistent. Image quality was evaluated using absolute visual grading analysis (VGA) with contrast-to-noise ratio (CNR) also calculated for comparison. Effective dose was established using Monte Carlo simulation using entrance surface dose within its calculations.

RESULTS

VGA and CNR reduced significantly (p < 0.05) whilst effective dose increased significantly (p < 0.05) for images acquired using the incubator tray. The optimal combinations of parameters for incubator imaging were: image receptor directly behind neonate, 0.5 mAs, 60 kV at 100 cm SID, however, if tray needs to be used then these need to be adapted to: 1 mAs at maximum achievable SID. Effective dose was highest for images acquired using both incubator tray and 100 cm SID owing to a decrease in focus to skin distance. There is significant increase (p < 0.01) in VGA between using 0.5 mAs and 1 mAs but an apparent lack of increase between 1 and 1.5 mAs.

CONCLUSION

Using the incubator tray has an adverse effect on both image quality and radiation dose for incubator imaging. Direct exposure is optimal for this type of examination but if tray needs to be used, both mAs and SID need to be increased slightly to compensate.

IMPLICATIONS FOR PRACTICE

This study can help inform practice in order to both standardise and optimise chest imaging for neonates in incubators.

Neonatal chest radiography: Influence of standard clinical protocols and radiographic equipment on pathology visibility and radiation dose using a neonatal chest phantom

INTRODUCTION

Little is known about the variations in pathology visibility (PV) and their corresponding radiation dose values for neonatal chest radiography, between and within hospitals. Large variations in PV could influence the diagnostic outcome and the variations in radiation dose could affect the risk to patients. The aim of this study is to compare the PV and radiation dose for standard neonatal chest radiography protocols among a series of public hospitals.

METHODS

A Gammex 610 neonatal chest phantom was used to simulate the chest region of neonates. Radiographic acquisitions were conducted on 17 X-ray machines located in eight hospitals, utilising their current neonatal chest radiography protocols. Six qualified radiographers assessed PV visually using a relative visual grading analysis (VGA). Signal to noise ratios (SNR) and contrast to noise ratios (CNR) were measured as a measure of image quality (IQ). Incident air kerma (IAK) was measured using a solid-state dosimeter.

RESULTS

PV and radiation dose varied substantially between and within hospitals. For PV, the mean (range) VGA scores, between and within the hospitals, were 2.69 (2.00-3.50) and 2.73 (2.33-3.33), respectively. For IAK, the mean (range), between and within the hospitals, were 24.45 (8.11-49.94) μGy and 34.86 (22.26-49.94) μGy, respectively.

CONCLUSION

Between and within participating hospitals there was wide variation in the visibility of simulated pathology and radiation dose (IAK).

IMPLICATIONS FOR PRACTICE

X-ray units with lower PV and higher doses require optimisation of their standard clinical protocols. Institutions which can offer acceptable levels of PV but with lower radiation doses should help facilitate national optimisation processes.

A comparative study of pain experienced during successive mammography examinations in patients with a family history of breast cancer and those who have had breast cancer surgery

INTRODUCTION

To measure mammography-related pain in two groups of women undergoing regular surveillance as a baseline for future care.

METHODS

Following ethical approval, two hundred and forty two women aged 32-84 years (mean 54), were invited by written invitation to participate in the study. Two hundred women accepted the invitation, 100 women had a family history (FH) of breast cancer, 100 had undergone conservative surgery (FU) for breast cancer and were currently asymptomatic. A validated pain scale was used to score the participants' perceived pain before compression based on memory, immediately after compression and one week later. A series of baseline parameters were also captured including compression force, breast size/density, menstrual history and any adverse events following mammography to allow the investigation of relationships.

RESULTS

There was a strong correlation (r = 0.79, p < 0.001) between previous pain scores and current pain scores, no significant correlations were found between breast size, breast density or total compression force and pain. Pain scores reduced between previous and current examinations and there was consistency in overall pain scores, despite variations in the compression forces applied.

CONCLUSION

Physical side effects from mammography can develop and extend beyond the examination period. Patients' prior experience of pain was the only significant predictor of current pain in this study.

IMPLICATIONS FOR PRACTICE

Data on past mammography experiences are essential to improve future pain outcomes. Post-mammography aftercare should be a routine feature of the examination.

Imaging neonates within an incubator - A survey to determine existing working practice

INTRODUCTION

There is limited and confusing evidence within the literature regarding the optimal techniques when imaging neonates within incubators; in particular, whether to place the image receptor directly behind the neonate or in the incubator tray. For this reason, radiology departments across Wales and North West England were surveyed to explore existing working practice with regards to incubator imaging.

METHOD

A self-designed survey was developed using a systematic approach. The survey was sent to 31 radiology departments across Wales and North West England whom had a neonatal unit in order to assess existing techniques used when imaging neonates within the incubator. The survey was split into three main domains: 1) general/demographics, 2) exposure factors and technique, and 3) incubator design.

RESULTS

Nineteen departments responded (64%) demonstrating a wide variation in practice for incubator imaging. The minimum and maximum exposure factors used for neonatal chest x-ray imaging varied from 55 kV to 65 kV and 0.5 mAs-2 mAs. Fifty-eight percent of departments used the incubator tray as standard practice with the remaining forty two percent not using the tray for various reasons including, image quality, artefacts and misalignment. Sixty-three percent of departments use the maximum achievable SID for incubator imaging which demonstrates wide variability as the SID would be dependent upon: incubator design, portable machine and radiographer height.

CONCLUSION

The survey demonstrates a wide variation in existing practice for neonatal incubator imaging.

IMPLICATIONS FOR PRACTICE

This study supports the need for standardisation and further optimisation work to ensure best practice for this vulnerable patient group.

Initial single centre experiences of a radiographer advanced practitioner led nephrostomy exchange programme

INTRODUCTION

To evaluate the technical success, radiation dose, complications and costs from the introduction of a radiographer-led nephrostomy exchange service.

METHODS

Post-graduate qualified interventional radiographers with several years' experience in performing other interventional procedures began performing nephrostomy exchanges. Training was provided by an interventional radiologist. Each radiographer performed ten procedures under direct supervision followed by independent practice with remote supervision. Each radiographer was then responsible for the radiological report, discharge, re-referral for further exchange and, where indicated, sending urine samples for culture and sensitivity. Data extraction included the time interval between exchanges, radiation dose/screening time and complications.

RESULTS

Thirty-eight long-term nephrostomy patients had their histories interrogated back to the time of the initial insertion. The mean (range) age at nephrostomy insertion was 67 (35-93) years and 65% were male. Indications for nephrostomy were prostatic or gynaecological malignancy, ureteric injury, bulky lymphoma and post-transplant ureteric stricture. A total of 170 nephrostomy exchanges were performed with no statistically significant differences in the radiation dose, fluoroscopy time nor complication rates between consultants and radiographers. There was, however, a statistically significant reduction in the time interval between nephrostomy exchanges for the radiographer group (P = 0.022).

CONCLUSION

Interventional radiographers can provide a safe, technically successful nephrostomy exchange program with radiation doses equivalent to radiologists. This is a cost-effective solution to the capacity issues faced in many departments, whilst providing career progression, job satisfaction and possibly improved care.

IMPLICATIONS FOR PRACTICE

Radiographer-led interventional services should be considered by other institutions as a means of providing effective nephrostomy exchanges.

Video rasterstereography of the spine and pelvis in eight erect positions: A reliability study

INTRODUCTION

To investigate the reliability and variability of Video Rasterstereography (VR) measurements of the spine and pelvis, for eight proposed standing postures, in order to help define an optimal standing position for erect pelvis radiography.

METHODS

Surface topography data were collected using the formetic 4D dynamic modelling (Diers) system. 61 healthy participants were recruited; each participant performed eight different standing positions. Four positions were performed with the feet shoulder width apart and parallel, and four positions were performed with the feet shoulder width apart and internally rotated. For the upper extremity, each of the (two sets of) four positions were performed with different arm positions (arms by the sides, arms crossed over the chest, arms 30° flexed and touching the medial end of the clavicle, arms 30° flexed with the hands holding a support). Three sets of surface topography were collected in the eight positions (n = 24). The variability was assessed by calculating standard error of the measurement (SEm) and the coefficient of variation (CV). Reliability was assessed using intra-class correlation coefficients (ICC ± 95% CI).

RESULTS

No significant differences in the SEm were found between the three paired measurements for all standing positions (P > 0.05). ICC values demonstrated excellent reliability for all measurements across the eight standing positions (range 0.879-1.00 [95% CI 0.813-1.00]).

CONCLUSION

Evaluating eight standing positions radiographically would be unethical as it would involve repeat radiation exposures. Using the formetic 4D dynamic modelling (Diers) system, provides an alternative and has shown that there was only a minimal, non-statistically significant, differences between the eight different standing positions.

IMPLICATION FOR PRACTICE

Different standing positions were proposed for erect pelvis radiography.

An investigation into the perceived value of the College of Radiographers voluntary accreditation scheme for advanced and consultant practitioners in breast imaging

INTRODUCTION

A voluntary accreditation scheme has been introduced, requiring advanced (AdP) and consultant practitioners (CP) to submit several pieces of work to the College of Radiographers (CoR). However, few individuals have opted to become voluntary accredited. This study investigated the reasons behind becoming voluntary accredited, the value that was gained and why there appears to be a lack of support for the scheme.

METHODS

An online electronic survey was conducted using a mixed methods approach. Open questions enabled individual opinions and thoughts to be expressed, Likert scale style questions allowed further understanding of the level of agreement and closed questions identified the support for and against the scheme.

RESULTS

A total of 55 respondents participated, including 18 AdPs, 25 CPs, 1 consultant trainee practitioner, 5 practitioners and 6 listed as 'other'. Forty-four participants were non-accredited, citing too much clinical work; no recognition from employers and too much effort for little reward. Motivations for joining the scheme were to improve the profession; help create a new consultant post and protect the non-clinical element of the consultant role.

CONCLUSION

The CoR voluntary accreditation scheme has a small perceived value but overall, the majority of respondents believed the scheme did not warrant the work needed to apply. Concern was raised about the risk of creating a two-tier profession by the scheme's instigation. The results of this study suggest that the CoR's voluntary accreditation scheme would need to address these barriers before more practitioners would apply.

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.

Estimating the error of CT-based measurements of aortic lumen volume used in endovascular planning

INTRODUCTION

Planning of endovascular sealing of abdominal aortic aneurysms requires measurement of the aortic lumen volume. The aim of this study was to investigate mathematically the effect of intra- and inter-observer variability error, as well as cardiac cycle-related variability, on these measurements.

METHODS

Mean (±2SD) intra- and inter-observer error in lumen measurements and mean (+2SD) cardiac cycle-related variability were obtained from published literature and added to the measurement of the flow lumen volume of a 57 mm abdominal aortic aneurysm to calculate average and extreme error possibilities.

RESULTS

The aneurysm volume was measured at 165 ml. The calculated possible mean measurement error due to cardiac cycle variation, intra- and inter-observer variability was +11.0%, resulting in a potential measurement of 183.1 ml. The calculated extreme errors were +24.3% (if 2SD of all errors were added to the mean) and +3.5% (if 2SD of all errors, except cardiac cycle, were subtracted from the mean), resulting in potential measurements of 170.8 ml and 205.1 ml, respectively. When considering the errors combined, the proportion of patients who may have volume measurement errors of up to ±2.5 ml, ±2.6 to ±5.0 ml and ±5.1 to ±7.5 ml were 18%, 17% and 15%, respectively.

CONCLUSION

Measurement of CT-based aortic lumen volumes in abdominal aortic aneurysms is imprecise. This has practical implications for the planning and the performance of complex endovascular therapies.

Antero-posterior (AP) pelvis x-ray imaging on a trolley: Impact of trolley design, mattress design and radiographer practice on image quality and radiation dose

INTRODUCTION

Physical and technical differences exist between imaging on an x-ray tabletop and imaging on a trolley. This study evaluates how trolley imaging impacts image quality and radiation dose for an antero-posterior (AP) pelvis projection whilst subsequently exploring means of optimising this imaging examination.

METHODS

An anthropomorphic pelvis phantom was imaged on a commercially available trolley under various conditions. Variables explored included two mattresses, two image receptor holder positions, three source to image distances (SIDs) and four mAs values. Image quality was evaluated using relative visual grading analysis with the reference image acquired on the x-ray tabletop. Contrast to noise ratio (CNR) was calculated. Effective dose was established using Monte Carlo simulation. Optimisation scores were derived as a figure of merit by dividing effective dose with visual image quality scores.

RESULTS

Visual image quality reduced significantly (p < 0.05) whilst effective dose increased significantly (p < 0.05) for images acquired on the trolley using identical acquisition parameters to the reference image. The trolley image with the highest optimisation score was acquired using 130 cm SID, 20 mAs, the standard mattress and platform not elevated. A difference of 12.8 mm was found between the image with the lowest and highest magnification factor (18%).

CONCLUSION

The acquisition parameters used for AP pelvis on the x-ray tabletop are not transferable to trolley imaging and should be modified accordingly to compensate for the differences that exist. Exposure charts should be developed for trolley imaging to ensure optimal image quality at lowest possible dose.

Clinical radiography education across Europe

PURPOSE

To establish a picture of clinical education models within radiography programmes across Europe by surveying higher education institutions registered as affiliate members of the European Federation of Radiography Societies (EFRS).

METHOD

An online survey was developed to ascertain data on: practical training, supervisory arrangements, placement logistics, quality assurance processes, and the assessment of clinical competencies. Responses were identifiable in terms of educational institution and country. All educational institutions who were affiliate members at the time of the study were invited to participate (n = 46). Descriptive and thematic analyses are reported.

RESULTS

A response rate of 82.6% (n = 38) was achieved from educational institutions representing 21 countries. Over half of responding institutions (n = 21) allocated in excess of 60 European Credit Transfer and Accumulation System (ECTS) credits to practical training. In nearly three-quarters of clinical placements there was a dedicated clinical practice supervisor in place; two-thirds of these were employed directly by the hospital. Clinical practice supervisors were typically state registered radiographers, who had a number of years of clinical experience and had received specific training for the role. Typical responsibilities included monitoring student progress, providing feedback and completing paperwork, this did however vary between respondents. In almost all institutions there were support systems in place for clinical placement supervisors within their roles.

CONCLUSIONS

Similarities exist in the provision of clinical radiography education across Europe. Clinical placements are a core component of radiography education and are supported by experienced clinical practice supervisors. Mechanisms are in place for the selection, training and support of clinical practice supervisors. Professional societies should work collaboratively to establish guidelines for effective clinical placements.