A new standard in testing mattresses for use in x-ray imaging : developing, validating and using a novel method to test x-ray mattresses for pressure ulcer development, radiation dosimetry and image quality

Alresheedi, N

Abstract

Background
In hospitals, patients often undergo X-ray imaging while lying on a mattress. Therefore, mattresses must have low X-ray attenuation properties to minimise radiation dose to the patient. Mattresses should create no artifacts within the X-ray image, as this may compromise image quality and diagnosis. Finally, mattresses should be constructed in such a way that interface pressure (IP) is minimized, limiting the chance of pressure ulcer formation.
Aim
For evaluating X-ray imaging table mattresses, this thesis has three aims (1). to develop and validate an anthropomorphic-phantom-based method of assessing X-ray table mattress IP as an index of mattress performance; (2) to assess X-ray table mattress pressure redistribution properties; and (3) to evaluate mattress radiation attenuation characteristics and their impacts on image quality.
Methods and Materials
An anthropomorphic phantom, simulating adult head, pelvis, and heels, was 3D-printed from X-ray computed tomography (CT) image data. Dry sand was added to represent 5 human weights and XSensor technology was used to assess pressure distribution. Phantom mattress IP characteristics were compared for the 5 weights against 27 sets of human mattress IP data to achieve phantom validation. Twenty-four X-ray table mattresses, 21 thinner and 3 thicker were assessed. Anthropomorphic phantom and Xsensor mattress interface pressure measurements were conducted for head, pelvis and heels, with and without X-ray table mattresses. Image quality and radiation attenuation were also assessed. Incident air kerma (IAK) was measured, with and without mattress, over a range of exposure factors using a digital dosimeter. Inverse image Quality Factor (IQFinv) was calculated to assess image quality using a commercially available phantom (CDRAD).
Results
The anthropomorphic phantom proved suitable for use in this thesis - based on correlation coefficient R values, there was a good correlation for the 5 phantom weights between the phantom and human pressure data. (R values: head =0.993, pelvis =0.997, and heels =0.996). There were statistically significant differences (p<0.05) between peak pressure values with and without X-ray table mattress for head, pelvis and heels. Additionally, there were statistically significant differences (p<0.05) between the IP ratio values with and without X-ray table mattresses. The type and age of the mattresses also had an impact on peak pressure values and IP ratios. IAK and image quality measures were impacted by mattress addition. IAK values decreased because of attenuation, with IQFinv having worse image quality. There was a negative correlation between mattress age and IAK, meaning that older mattresses had higher attenuation properties. The clinical impact of this finding, for the potential for radiation increase, was insignificant. No correlation was found between image quality and age. Conclusion
A novel method for testing X-ray mattress IP was established and validated in this thesis. This method could be valuable for aiding mattress design and development and subsequent testing when in clinical use. For new mattresses, peak pressure values and IP ratios were greatly reduced, compared with older ones. The impact mattresses had on radiation attenuation and image quality are clinically insignificant.

Citation

Alresheedi, N. A new standard in testing mattresses for use in x-ray imaging : developing, validating and using a novel method to test x-ray mattresses for pressure ulcer development, radiation dosimetry and image quality. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Apr 21, 2021
• Publicly Available Date: Apr 21, 2021
• Award Date: Aug 26, 2020