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Discrimination of Photoneutron Generation Among Conventional Wedge and 3D-CRT Treatment Planning for Breast Cancer Practicing in a 10 and 15 MV Megavoltage X-Rays Beams

H Ali sahib1 , G Bharanidharan2*, N Sekar3 , D Mohapatra4 , A Prakasarao5 , S Jagadeesan6 , J Vellingiri7 , G Singaravelu8 , p Mahadevan9 , K Karuppasamy10 , M Murgan11 , (1) Anna University, Chennai, ,(2) Anna University, Chennai, ,(3) Anna University, Chennai, ,(4) 2Reactor and Radiological Safety Section, Safety Research Institute - Atomi, Chennai, ,(5) Anna University, Chennai, ,(6) VPS Lakeshore Hospital, Kochi, ,(7) VPS Lakeshore Hospital, Kochi, ,(8) Anna University, Chennai, ,(9) VPS Lakeshore Hospital, Kochi, ,(10) VPS, Ernakulam, KL, (11) VPS Lakeshore Hospital, Kochi,


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: To analyzing the dosimetric parameter for breast radiotherapy planning and estimation of photoneutron contamination generated from conventional wedge and 3D-CRT (FIF) treatment plan.

Methods: Breast cancer patient having higher separation was selected retrospectively in the current study. The planning target volume (PTV) and organ at risk (OAR) were contoured according to RTOG protocol. Conventional wedge plan (150 wedge angle) and 3D-CRT RT plans were generates using Collapsed cone convolution algorithm. Plan evaluation was performed using dose volume histogram. The plan was executed in 30x30*20cm PTW slab phantom and the photoneutron dose equivalent (PNDE) was evaluated using BD-PND bubble detector (1.2 bubbles / µSv) measured at 50, 100and 150 cm from field edge along the patient plane for both 10 and 15 MV beams using Elekta Versa HD clinical linac.

Results: The results shows that 3D-CRT (FIF) techniques has better conformity and homogeneity index, V95% i.e. 3D-CRT received higher PTV volume, PTV-Dmean, dose to heart, ipsilateral lung, contralateral breast and lung dose didn’t have any significant variation then conventional wedge plan. The PNDE measured at a distance of 50, 100 and 150 cm were 551, 425 & 352µSv for 10 MV and 1130, 868 & 733 µSv for 15 MV wedge plans. In case of 3D-CRT technique, the PNDE estimated at above distances were 532, 382 & 333 µSv and 985, 741 & 641µSv for 10 and 15 MV respectively.

Conclusion: The 3D-CRT technique exhibits lower photoneutron contamination than wedge plan. The Photoneutron dose equivalent estimation was found to be higher for 15 MV than 10MV.


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TH- External beam- photons: out of field dosimetry/risk analysis

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