Estimation of peripheral dose from Co60 beam in water phantom measured in Secondary Standard Dosimetry Laboratory, Pakistan

Publication date: May–June 2017
Source:Reports of Practical Oncology & Radiotherapy, Volume 22, Issue 3
Author(s): Muhammad Shahban, Babar Hussain, Khalid Mehmood, Shakeel Ur Rehman
BackgroundPeripheral or scatter dose harms neighbouring normal tissues during administration of dose to cancerous tissues, therefore, knowledge of peripheral dose is an important consideration in radiotherapy.AimIn present study, absorbed dose measurements in a water phantom were performed for three field sizes, 7×7cm², 10×10cm² and 15×15cm².Materials and methodsFor each field size, dose was measured at six depths below the front surface of the water phantom; 2.5–15cm with an interval of 2.5cm. Measurements were made at equal transverse distances along the horizontal axis, from 1cm to 6cm, on both sides of the central beam axis and normalized with central axis dose of each field. All measurements were made at the source to surface distance of 100cm.ResultsVariation of peripheral dose with lateral distance was analysed and an appropriate parametric equation for each field size and depth was constructed.ConclusionsThe peripheral radiation dose showed a strong dependence on field size and distance from field boundary.



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