Microdosimetric single-event spectra for megavoltage electrons

Journal Article · Sun Jul 01 00:00:00 EDT 1990 · Medical Physics; (USA)

DOI:https://doi.org/10.1118/1.596490· OSTI ID:6375926

Zellmer, D L ^[1]; Amols, H I ^[2]

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1. Radiation Oncology Department, Medical College of Wisconsin, Milwaukee, WI (USA)
2. Department of Radiation Oncology, Columbia University, New York, NY (USA)

Experimental techniques have been developed for obtaining single-event microdosimetric spectra from hospital based linear accelerators. Therapeutic electrons of 12, 15, 18, and 20 MeV from Clinic 18 and 20 accelerators have been produced at ultralow dose rates. Details of the experimental methods have been described previously by the authors. Single-event lineal energy spectra for these beams, as measured by a Rossi chamber differ significantly from cobalt-60 both in shape and dose average lineal energy ({ital {bar y}}{sub {ital d}}) which, depending on electron energy, can be 20--40% lower. The spectral peaks for electrons are greatly enhanced compared to cobalt. The {ital {bar y}}{sub {ital d}} for electrons also differs from previously reported values for 10--15-MV photon beams. These differences are less pronounced than for differences with cobalt. Spectral peaks and shapes correlate well with the actual electron stopping powers in tissue. The theory of dual radiation action predicts changes in relative biological effectiveness at low doses for megavoltage photon and electrons. Although at clinical doses the predicted differences are not statistically significant.

• OSTI ID: 6375926
• Journal Information: Medical Physics; (USA), Vol. 17:4; ISSN 0094-2405
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ELECTRON BEAMS
ELECTRON SPECTRA
MICRODOSIMETRY
DOSE RATES
LET
LINEAR ACCELERATORS
MEV RANGE 10-100
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RBE
ACCELERATORS
BEAMS
DOSIMETRY
ENERGY RANGE
ENERGY TRANSFER
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430303* - Particle Accelerators- Experimental Facilities & Equipment