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Detection of Architectural Distortion in Prior Mammograms via Analysis of Oriented Patterns
Published on: August 30, 2013
Film based scatter measurement in mammography
D McLean1, L Ainley, K Blackett
1School of Medical Radiation Sciences, University of Sydney, Lidcombe, NSW. D.McLean@cchs.usyd.edu.au
Australasian Physical & Engineering Sciences in Medicine
|August 2, 2000
Summary
Scatter to primary ratio (s/p) measurements in mammography show it is uniform across images, decreasing at the edges. S/p increases with phantom thickness but is unaffected by material type.
Area of Science:
- Medical Physics
- Radiological Imaging
- Biomedical Engineering
Background:
- Accurate scatter to primary ratio (s/p) measurement is crucial for optimizing mammographic imaging quality and radiation dose.
- Previous s/p estimations relied heavily on Monte Carlo simulations, necessitating experimental validation.
- Understanding factors influencing s/p, such as phantom composition and beam parameters, is key to improving diagnostic accuracy.
Purpose of the Study:
- To experimentally determine the scatter to primary ratio (s/p) using film-based techniques in mammography.
- To investigate the influence of phantom material (glandular, adipose, mixed), thickness, field size, and beam energy on s/p.
- To compare experimental s/p values with those obtained from Monte Carlo calculations.
Main Methods:
- Film-based measurements utilizing the "beam stop" technique were performed.
- Phantoms simulating 100% glandular, 100% adipose, and 50/50% glandular/adipose tissue were used.
- Measurements were conducted at various kilovolt peak (kVp) settings (25-30 kVp), with and without a grid, across a range of phantom thicknesses (3-7 cm) and field sizes (80-290 cm²).
Main Results:
- Scatter to primary ratio (s/p) was found to be largely uniform across the mammographic image, with a slight reduction towards the phantom edges.
- S/p demonstrated a direct proportionality to phantom thickness, with minimal dependence on field size.
- The effect of beam energy on s/p was significant without a grid but less pronounced when a grid was employed.
- Experimental s/p values closely aligned with published Monte Carlo simulation results.
- No significant variation in s/p was observed between different phantom tissue compositions.
Conclusions:
- Film-based measurements confirm Monte Carlo predictions for scatter to primary ratio in mammography.
- Phantom thickness is the primary determinant of s/p, followed by beam energy (especially without a grid).
- The use of a grid effectively mitigates the impact of beam energy on s/p.
- Mammographic phantom material composition does not significantly alter the scatter to primary ratio.
