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[Absorbed dose conversion factors obtained from X-ray spectra measured at water phantom surface]
1Department of Radiological Sciences, Faculty of Health Sciences, Komazawa University.
Nihon Hoshasen Gijutsu Gakkai Zasshi
|April 9, 2005
Summary
Accurate absorbed dose conversion factors for X-rays were determined using measured spectra. These factors differ from those calculated using primary X-ray spectra, especially for high-voltage and filtered X-rays.
Area of Science:
- Medical Physics
- Radiation Dosimetry
Context:
- Accurate absorbed dose determination is crucial in radiation therapy and diagnostic imaging.
- X-ray dosimetry requires precise conversion factors, particularly at the water phantom surface.
Purpose:
- To measure and determine the absorbed dose conversion factor for X-rays at the water phantom surface.
- To compare measured conversion factors with those derived from primary X-ray spectra and effective energy calculations.
Summary:
- Absorbed dose conversion factors were measured for X-rays (60-120 kV, 5x5 to 30x30 cm² fields) using a silicon diode detector.
- Measured factors were 0.03-0.43% lower than those from primary spectra, with larger discrepancies for high-voltage and filtered X-rays.
- Conversion factors decreased slightly with increasing field size, particularly beyond 20x20 cm².
Impact:
- Provides more accurate absorbed dose conversion factors for clinical X-ray dosimetry.
- Highlights the limitations of using primary X-ray spectra or effective energy for precise dose calculations.
- Improves radiation dose assessment in medical imaging and therapy.