Quantitative estimation of Integral doses (ID) and skin entry exit doses during different radiation treatment delivery techniques for craniospinal irradiation patients.

Document Type : Original Paper

Authors

1 Lovely Professional University

2 Lovely Professional University, Jalandhar, Punjab , India

3 Department of Radiation Oncology, Mohan Dai Oswal Cancer Hospital and Research Foundation, Ludhiana Punjab 141009 India

Abstract

Introduction: Radiation treatment delivery techniques like HIMRT and VMAT are based on arcs. Advancement technology has improved the treatment delivery, but in helical treatment delivery, there are chances that patient will get low doses to large volume because of beam entry through 360 degree. These low doses can cause radiation injury to cells which can result in late side effects. . Dose at any point in the patient is combination of beam entry dose and beam exit dose. The skin dose depends on various factors such as type of energy, field size, gantry angle, fractionation pattern, shape and size of target volume and lack of backscatter. This comparison is a method to check which type of treatment planning delivery is giving best result in terms of skin sparing.

Materials and Methods: For this study we have taken 20 patients suffered from meduloblastoma and planned for Craniospinal irradiation (CSI) with HIMRT, H3DCRT and VMAT treatment planning techniques on Accuray Radixact X9 and Elekta Synergy (Agility) linear accelerator. Skin entry and exit doses, has been calculated at different points and average value has been taken. Skin-Ring has been generated by taking negative 3mm margin from skin.

Results: Various dosimetric parameters like Dmax, Dmean, D80%, D50%, D30% and D10% has been calculated for skin and skin_ring. Integral doses has been calculated for PTV-Brain and PTV-Spine, taking into consideration of at least V95% (target coverage by 95% of prescribed dose). Statistical Analysis has been done with SPS software version 22. Skin entry exit doses and integral doses were observed high in H3DCRT and then HIMRT whereas VMAT plans show minimum entry exit doses and integral doses or phase-1 and phase-2.

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Iranian Journal of Medical Physics

Articles in Press, Accepted Manuscript
Available Online from 02 July 2023

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History

  • Receive Date: 07 March 2023
  • Revise Date: 21 June 2023
  • Accept Date: 02 July 2023

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