C Esquivel, T Roberts, A Tipton, O Calvo*, L Patton, Texas Oncology, San Antonio, San Antonio, TX

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  O Calvo

PO-GePV-T-96 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: Assess the use of an automated plan analysis software embedded within the treatment planning system to evaluate composite hypofractionated plans of varying fractional dose using biologically effective dose (BED) and equivalent dose at 2 Gray (EQD2) constraints.

Methods: Ten hypofractionated treatment plans of varying anatomical site and fractional dose were retrospectively reviewed using the Eclipse-integrated plan assessment tool, ClearCheck. From published material, BED tolerances were derived for several normal tissue structures and utilized as dose constraints. With the dose conversion tool, the hypofractionated doses were converted to EQD2 values. The automated plan check converts each dose voxel to a BED or EQD2 value before summing them in the composite plan, with subsequent evaluation of the plan against the radiobiological dose tolerances. Biological dose conversion was compared to MIM, which creates a converted dose matrix that was then exported for evaluation in ClearCheck. The dose conversion feature of the software was evaluated with each composite plan, with an added emphasis on the radiobiological concepts of BED and EQD2.

Results: While smaller volume structures were noted to have greater variation in biological values between ClearCheck and MIM, most cases demonstrated nearly identical agreement. Appropriate performance and functionality were confirmed for the software evaluation of hypofractionated PlanSums. ClearCheck can additionally consider repair in the evaluation and display the DVH in terms of BED and EQD2.

Conclusion: ClearCheck is a beneficial tool in the assessment of composite plans of variable fractional doses as it relates to BED dose constraints and converted EQD2 values. Constraints are created at the user’s discretion and can be expressed in terms of maximum dose, mean dose, or dose to a specified volume. Along with the planner’s ability to modify the α/β ratio, there is an instantaneous assessment of the treatment plan and the two radiobiological parameters.

Keywords

Treatment Planning, Radiobiology, Software

Taxonomy

TH- External Beam- Photons: General (most aspects)

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