Electron dose rate and photon contamination in electron arc therapy

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Medical Physics; (USA)

DOI:https://doi.org/10.1118/1.596328· OSTI ID:5118595

Pla, M; Podgorsak, E B; Pla, C ^[1]

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1. McGill Univ., Montreal, Quebec (Canada)

The electron dose rate at the depth of dose maximum dmax and the photon contamination are discussed as a function of several parameters of the rotational electron beam. A pseudoarc technique with an angular increment of 10 degrees and a constant number of monitor units per each stationary electron field was used in our experiments. The electron dose rate is defined as the electron dose at a given point in phantom divided by the number of monitor units given for any one stationary electron beam. For a given depth of isocenter di the electron dose rates at dmax are linearly dependent on the nominal field width w, while for a given w the dose rates are inversely proportional to di. The dose rates for rotational electron beams with different di are related through the inverse square law provided that the two beams have (di,w) combinations which give the same characteristic angle beta. The photon dose at the isocenter depends on the arc angle alpha, field width w, and isocenter depth di. For constant w and di the photon dose at isocenter is proportional to alpha, for constant alpha and w it is proportional to di, and for constant alpha and di it is inversely proportional to w. The w and di dependence implies that for the same alpha the photon dose at the isocenter is inversely proportional to the electron dose rate at dmax.

• OSTI ID: 5118595
• Journal Information: Medical Physics; (USA), Journal Name: Medical Physics; (USA) Vol. 16:5; ISSN 0094-2405; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
655003* -- Medical Physics-- Dosimetry
CONTAMINATION
DEPTH DOSE DISTRIBUTIONS
DOSES
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
LEPTONS
MASSLESS PARTICLES
MEDICINE
MOCKUP
NUCLEAR MEDICINE
PHANTOMS
PHOTONS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
SPATIAL DOSE DISTRIBUTIONS
STRUCTURAL MODELS
THERAPY