Lead as surface bolus for high-energy photon and electron therapy
Dose distributions were evaluated under thin sheet lead used as surface bolus for 4- and 10-MV photons and 6- and 9-MeV electrons using a parallel-plate ion chamber and film. A narrow, significantly low dose region (-17%) was noted for 4-MV photons, whereas a 6% increase in dose was present for 10-MV photons. The dose was elevated 15%-22% near the surface of electron fields with lead bolus, but depth dose relationships were similar to soft-tissue-equivalent (STE) bolus. Investigation of partial-field bolus (2-cm-diam circle) documented reduced doses due to lack of lateral electron equilibrium for 10-MV photons, which was less evident using lead, and large edge effects (up to 30%) for electrons using either lead or STE bolus. Dose distributions on sloped surfaces with electron fields were similar for lead and STE; both require thickness adjustment to achieve a desired effective thickness normal to the surface. Lead bolus has been used successfully in clinical practice for photons.
- Research Organization:
- Reading Hospital and Medical Center, PA
- OSTI ID:
- 5409050
- Journal Information:
- Med. Phys.; (United States), Vol. 2
- Country of Publication:
- United States
- Language:
- English
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A surface bolus material for high-energy photon and electron therapy
A surface bolus material for high-energy photon and electron therapy
Related Subjects
LEAD
USES
RADIATION DOSE DISTRIBUTIONS
EVALUATION
ELECTRONS
IONIZATION CHAMBERS
PHOTONS
RADIATION DOSES
RADIOTHERAPY
TISSUE-EQUIVALENT MATERIALS
DOSES
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
LEPTONS
MASSLESS PARTICLES
MATERIALS
MEASURING INSTRUMENTS
MEDICINE
METALS
NUCLEAR MEDICINE
RADIATION DETECTORS
RADIOLOGY
THERAPY
655003* - Medical Physics- Dosimetry