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Dosimetric
evaluation of matching Co-60 and electron fields for treatment of head and
neck cancers |
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G. Kemikler |
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Istanbul
University, Oncology Institute, Department of Medical Radiophysics, Topkapi,
34390, |
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Manuscript received: Accepted for publication: Abstract The management of head and neck
tumours frequently requires matching photon and electron fields. Enface electron .elds are employed to boost the dose
to the tissues overlying the spinal cord. The objective of this study is to
measure the dose distribution in the matched region between the
opposing Co-60 and the enface electron fields. In this study .lm dosimetry technique was applied
to measure dose pro.les at depths of 1, 2, and 3 cm in the junction of the matching Co-60
and electron (9MeV) fields. To investigate the changes in the
dose distributions due to set-up uncertainties, dose profiles were measured at these depths
using 2-10 mm in 2 mm steps overlaps and gaps between the photon and electron
fields. The results showed that +20%
and – 9% dose inhomogeneities occurred at the
junction region at 1, 2, and 3 cm depth with 8 mm gap on the skin between the
fields. It was concluded that these
hot and cold spots might be clinically acceptable for the junction region
between Co-60 and electron fields. KEYWORDS: Photon-electron matching,
Head and neck irradiation, Dose nonuniformity. |
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