Accuracy Evaluation of Treatment planning Dose Calculation For 6MV Photon Beam

Document Type : Research

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Physics Department Faculty of Science Aswan University

Abstract

This study evaluates the dosimetric performance and accuracy of the Collapse cone photon dose calculation algorithm used in Monaco Plan. Dose distributions from the linear accelerator were evaluated for 6 photon beams using an ionization chamber in a water phantom. A comparison was made between these outcomes and further distributions obtained from the planning system.
methods: The 3D-water phantom system was used to measure the beam data, which included profiles (open square fields and wedged fields), percentage depth doses, and absolute dosimetry, for beam energy of 6 MV photon beams produced by the linear accelerator. The field sizes were 5 × 5 to 20 × 20 cm2, with corresponding depths of 5 cm, 10 cm, 15 cm, and 20 cm. These measurements were obtained in water using ionization chambers. Lastly, the measured values were compared with the calculated dose and various conditions. that comparison, we discovered that there was great agreement between the measured and calculated output doses. Under all parameters of energy, SSD, and field size, for both open and wedged fields, doses at depths below the maximum dosage calculated on-axis or off-axis in both the fields or penumbra region were found to be in good agreement with the observed dose. The only case where estimated and measured doses accord (with a difference of ≤3%) for photon 6 MV in the Central beam axis (&1) gradient.the deviations (&) of PPD curves show good agreement with the literature.the deviations (&) of PPD curves show good agreement with the literature.

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