1. Hayley Milne & Andrew England a.england@salford.ac.uk
Does using a lower kVp offer a greater potential for fracture detection in hip radiography?
Hayley Milne & Andrew England

2. Introduction elderly population suspected hip fractures
Prompt management essential (NICE, 2011)
Non-displaced hip fractures
Difficult to visualise
Low bone density (Butler et al., 2009)
kVp reduction  contrast

3. Aim
To investigate whether a reduction in the tube potential (kVp) will increase the visibility of the bony trabecular pattern on antero-posterior (AP) hip images.

4. Materials & Methods Acroma X-ray Unit Pelvis Phantom
Standard AP hip projection
100 cm SID
Central AEC chamber
Grid
Agfa CR receptor
Exposures (kVp)
50 – 100
Interval = 5 kVp
Effective Dose calculated
Images
3 per kVp setting
Pseudoanonymised

5. Image Quality Assessment
BACKGROUND
Physical
Signal-to-Noise Ratio (SNR)
Contrast-to-Noise Ratio (CNR)
Perceptual (Visual)
5 observers
2AFC
Image Quality Scale
Can the Principle Tensile Trabeculae (PTT) be visualised
Can the Greater Trochanter Trabeculae (GTT) be visualised
Can the Secondary Compressive Group (SCT) be visualised
Overall image quality

6. } 2AFC Technique REFERENCE EXPERIMENTAL 80 kVp 50 to 75 kVp
REFERENCE IMAGE
EXPERIMENTAL IMAGE }
Better than reference (4)
Equal to reference (3)
Worse than reference (2)
EACH SCALE ITEM (n = 4)

7. Results – Radiation Dose
47%

8. Results – Signal to Noise Ratio

9. Results – Contrast to Noise Ratio

10. Results – Perceptual (Visual)
5 observers
Final year students
Reference image

11. Summary Lowering tube potential (kVp) Further work Potential impact
Noticeable trends in the physical measures of trabecular pattern on AP hip radiographs
Low kVp = Higher CNR
No improvement in perceptual measures (high variability)
Further work
Clinical based studies needed
Include cases of osteoporosis / osteopenia / subtle fractures
Careful selection of IQ criteria + training
Potential impact
Low kVp acquisition parameters may provided an option for re-evaluating patients with suspected subtle hip fractures if other imaging modalities are not available.
May offer more speedier diagnosis than further imaging (MRI, CT or NM)

12. THANK YOU - ANY QUESTIONS?