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Feasibility of a Novel Conical Beam Arrangement in Radiation Therapy

E Schueler*, L Wang , B Loo , P Maxim , Stanford University Cancer Center, Stanford, CA


(Sunday, 7/29/2018) 1:00 PM - 1:55 PM

Room: Karl Dean Ballroom A1

Purpose: Traditionally in radiation therapy, treatments are delivered in a co-planar geometry. Numerous advantages have been reported of adding non-coplanar beams to the treatment plan yet the full exclusion of co-planar beams have not been specifically addressed. The aim of this study was to compare current state-of-the-art VMAT and CyberKnife treatment plans to that of a novel linac design developed at Stanford which employes a static conical beam arrangement, fully avoiding co-planar beams in the treatment plans.

Methods: A prostate and pediatric brain case was used for plan comparison. Conical IMRT plans with a 16-equidistant beam arrangement were studied and compared to plans generated for co-planar 90o VMAT and CyberKnife. The conical beam angle was set to 60 degrees with respect to the longitudinal axis of the patient.

Results: The prostate case showed larger differences in the dosimetric comparison between the different modalities as compared the prediatric brain case. Highest dose to the bladder and rectum while superior sparing of the femurs was found for the conical beam arrangement in the prostate case. The bladder and rectum dose was lowest for the VMAT and CyberKnife plans, respectively. In the pediatric brain case, only minor differences was found between the three modalities. For both sites, the conformity and homogeneity was similar for the conical and VMAT plan while higher indexes was found for the CyberKnife plans.

Conclusion: With conical beam arrangement, a comparable dose distribution could be achieved as compared to VMAT plans and a comparable or better plan compared to CyberKnife. The out-of-plane dose as well as the integral body dose was highest for the CyberKnife and lowest for the VMAT plans. This study shows that with the novel linac design being developed at Stanford, comparable plans to state-of-the-art modalities can be achieved.


Not Applicable / None Entered.


TH- External beam- photons: Development (new technology and techniques)

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