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A Novel Technique to Irradiate Surgical Scars Using Dynamic Electron Arc Radiotherapy

J Addido

J Addido1*, Q Wu2 , X Wang3 , (1) Duke Kunshan University, Kunshan, ,(2) Duke University Medical Center, Durham, NC, (3) Duke University Medical Center,


WE-RAM1-GePD-T-1 (Wednesday, August 2, 2017) 9:30 AM - 10:00 AM Room: Therapy ePoster Lounge

Purpose: When conformal electron beam therapy techniques are used to treat superficial tumors on uneven surfaces it can lead to undesired outcomes such as non-uniform dose inside target and wide penumbra at boundary of target. The dynamic electron arc radiotherapy (DEAR) technique has been demonstrated to improve dose distribution and minimize penumbra. The aim of this study is to investigate the feasibility and the accuracy of DEAR technique in irradiating surgical scars.

Methods: Given scar coordinates in 3D extracted from CT images, which is a series of connected points along a line, a treatment plan is designed to irradiate the scar with uniform dose. An algorithm was developed to produce DEAR plan consisting of control points corresponding to positions along machine axes as function of MU. Varian's SAGE software is used to verify and simulate the treatment and also to generate the plan in XML format. XML file is loaded on a TrueBeam in research mode.Irradiation is done on i) a straight line scar on the surface of a solid water phantom and ii) curved scar on the surface of a cylindrical phantom. Dose at the surface and dmax is measured with Gafchromic film. Dose profiles calculated from the Eclipse eMC and Virtual Linac are compared to film dose measurement

Results: The dose profile analysis show that the TrueBeam can deliver the plans for both straight line and arc scars with high accuracy. The root mean square error (RMSE), calculated using axes values from XML and trajectory log files is approximately 1.3 MU, 0.10 Gantry angle, 0.2 cm for couch lateral, 0.6 cm for couch vertical and 0.2 cm for couch longitudinal.

Conclusion: DEAR technique can be used to treat various line targets (scars) i.e. straight or curve line to a high degree of accuracy. DEAR can reinvigorate electron therapy.

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