Muhammad Shahban1, Babar Hussain2, Khalid Mehmood2, Shakeel Ur Rehman3. 1. Nuclear Medicine, Oncology and Radiotherapy Institute, Nawabshah, Pakistan. 2. Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan. 3. Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan.
Abstract
BACKGROUND: Peripheral 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. AIM: In present study, absorbed dose measurements in a water phantom were performed for three field sizes, 7 × 7 cm2, 10 × 10 cm2 and 15 × 15 cm2. MATERIALS AND METHODS: For each field size, dose was measured at six depths below the front surface of the water phantom; 2.5-15 cm with an interval of 2.5 cm. Measurements were made at equal transverse distances along the horizontal axis, from 1 cm to 6 cm, 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 100 cm. RESULTS: Variation of peripheral dose with lateral distance was analysed and an appropriate parametric equation for each field size and depth was constructed. CONCLUSIONS: The peripheral radiation dose showed a strong dependence on field size and distance from field boundary.
BACKGROUND: Peripheral 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. AIM: In present study, absorbed dose measurements in a water phantom were performed for three field sizes, 7 × 7 cm2, 10 × 10 cm2 and 15 × 15 cm2. MATERIALS AND METHODS: For each field size, dose was measured at six depths below the front surface of the water phantom; 2.5-15 cm with an interval of 2.5 cm. Measurements were made at equal transverse distances along the horizontal axis, from 1 cm to 6 cm, 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 100 cm. RESULTS: Variation of peripheral dose with lateral distance was analysed and an appropriate parametric equation for each field size and depth was constructed. CONCLUSIONS: The peripheral radiation dose showed a strong dependence on field size and distance from field boundary.
Entities:
Keywords:
Co60 beam; Peripheral dose; SSDL; Water phantom