beam hardening
The preferential filtering of low-energy photons from a radiation beam as it passes through tissue, resulting in a higher average energy.
Full Definition
Beam hardening occurs when a polychromatic radiation beam passes through matter, causing preferential absorption of lower energy photons while higher energy photons penetrate more deeply. This phenomenon affects dose calculations in treatment planning and must be accounted for in radiotherapy to ensure accurate dose delivery. The effect is more pronounced with thicker tissue sections and can impact treatment uniformity if not properly corrected in the planning system.
Usage
Usage note: Often confused with beam attenuation, which is the general reduction in beam intensity rather than the specific energy spectrum change.
In Context
- "The treatment planning system automatically corrected for beam hardening artifacts in the CT dataset." — Treatment planning report
- "Beam hardening effects were more pronounced in the patient's pelvic region due to bone density variations." — Physics quality assurance document