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Interactive Dose Shaping: Proof of Concept Study for Six Prostate Patients

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C Kamerling

CP Kamerling1,2*, P Ziegenhein1, F Sterzing2, U Oelfke1, (1) The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK, (2) German Cancer Research Center (DKFZ), Heidelberg, Germany,


SU-E-T-215 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: To provide a proof of concept study for IMRT treatment planning through interactive dose shaping (IDS) by utilising the respective tools to create IMRT treatment plans for six prostate patients.

Methods: The IDS planning paradigm aims to perform interactive local dose adaptations of an IMRT plan without compromising already established valuable dose features in real-time. Various IDS tools are available in our in-house treatment planning software Dynaplan and were utilised to create IMRT treatment plans for six patients with an adeno-carcinoma of the prostate. The sequenced IDS treatment plans were compared to conventionally optimised clinically approved plans (9 beams, co-planar). The starting point consisted of open fields. The IDS tools were utilised to sculpt dose out of the rectum and bladder. For each patient, several IDS plans were created, with different trade-offs between organ sparing and target coverage. The reference dose distributions were imported into Dynaplan. For each patient, the IDS treatment plan with a similar or better trade-off between target coverage and OAR sparing was selected for plan evaluation, guided by a physician. Pencil beam dose calculation was performed on a grid with a voxel size of 1.95x1.95x2.0 mm³. D98%, D2%, mean dose and dose-volume indicators as specified by Quantec were calculated for plan evaluation.

Results: It was possible to utilise the software prototype to generate treatment plans for prostate patient geometries in 15-45 minutes. Individual local dose adaptations could be performed in less than one second. The average differences compared to the reference plans were for the mean dose: 0.0 Gy (boost) and 1.2 Gy (CTV), for D98%: -1.1 Gy and for D2%: 1.1 Gy (both target volumes). The dose-volume quality indicators were well below the Quantec constraints.

Conclusion: Real-time treatment planning utilising IDS is feasible and has the potential to be implemented clinically.

Funding Support, Disclosures, and Conflict of Interest: Research at The Institute of Cancer Research is supported by Cancer Research UK under Programme C46/A10588.

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