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Optimization of radiographic technique for chest radiography
H M Warren-Forward1, J S Millar
1RRPPS, Birmingham Medical Physics Service, West Midlands, UK.
The British Journal of Radiology
|November 1, 1995
Summary
Patient entrance surface doses in chest radiography were monitored, revealing a mean of 0.15 mGy. Recommendations including increased kVp and optimized film-screen sensitivity could reduce doses by 53%.
Area of Science:
- Medical Physics
- Radiological Protection
- Diagnostic Imaging
Background:
- Patient entrance surface doses (ESD) in chest radiography are critical for radiation safety.
- Variability in imaging equipment and protocols can lead to inconsistent patient doses.
Purpose of the Study:
- To monitor patient ESD during chest radiography in the West Midlands.
- To assess the impact of various factors on patient dose and image quality.
- To recommend strategies for dose reduction.
Main Methods:
- Monitoring ESD for over 1500 patients using lithium borate thermoluminescent dosemeters.
- Assessing image quality of patient radiographs by departmental and independent radiologists.
- Evaluating film-screen processor sensitivity for 48 combinations.
Main Results:
- The mean patient ESD was 0.15 mGy, with a 75th percentile of 0.18 mGy.
- Significant discrepancies were found between nominal and measured film-screen sensitivities (only 26% within 10%).
- A regression model identified actual sensitivity, applied potential, generator waveform, and radiographic quality as key dose determinants.
Conclusions:
- A reference dose level of 0.18 mGy is recommended for PA chest radiography.
- Recommendations include increasing applied potential to 90 kVp, using film-screen sensitivity of 400, optimizing processors, and auditing to reduce repeat rates.
- Implementing these could achieve an estimated 53% reduction in ESD.