ESTRO 2024 - Abstract Book

S3583

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

We conclude that it is feasible to treat SIB prostate using FFF partial-arcs with an average treatment time of 74 seconds. This study presents insights into the potential advantages of FFF partial-arcs for prostate radiotherapy, not only in terms of treatment time but also in dose accuracy provided by the reduction in monitor units indicating less modulation on the treatment beams, leading potentially to more conformal treatment fields. The combination of significantly reduced treatment time and lower monitor units provided by FFF partial-arcs holds the potential to further address the issue of inherent anatomical motion. Excluding the posterior and anterior sectors from the treatment field arcs, we can reduce the rectum dose by design. Disadvantage of the shorter treatment fields is a moderately inferior dose homogeneity in the target - still maintaining sufficient clinical uniformity in the PTV of 5.2 percentage points in average. Also, marginally higher femoral heads median dose and larger spread of the 15 Gy dose volume were observed. Additionally, as prostate radiotherapy constitutes a substantial portion of the overall radiotherapy resources, achieving significant collective benefits is possible. Globally ~1.5 million patients are diagnosed with prostate cancer annually, with approximately a third receiving radiotherapy. By reducing the treatment time with one minute for each of these tens of millions of treatment fractions, the global cumulative benefit could amount to 200,000 hours of beam-on-time annually - equivalent to the total capacity of several hundred treatment machines.

Keywords: treatment duration, partial-arcs, VMAT planning

References:

[1] Langen KM, Jones DTL. Organ motion and its management. Int J Radiat Oncol Biol Phys. 2001;50(1):265-278. doi:10.1016/S0360-3016(01)01453-5.

[2] van der Heide UA, Kotte AN, Dehnad H, Hofman P, Lagenijk JJ, van Vulpen M. Analysis of fiducial marker-based position verification in the external beam radiotherapy of patients with prostate cancer. Radiother Oncol. 2007 Jan;82(1):38-45. doi: 10.1016/j.radonc.2006.11.002. Epub 2006 Dec 4. PMID: 17141903.

[3] Balter JM, Wright JN, Newell LJ, et al. Accuracy of a wireless localization system for radiotherapy. Int J Radiat Oncol Biol Phys. 2005;61(3):933-937. doi:10.1016/j.ijrobp.2004.11.009.

[4] Ballhausen H, Li M, Ganswindt U, Belka C. Shorter treatment times reduce the impact of intra-fractional motion: A real-time 4DUS study comparing VMAT vs. step-and-shoot IMRT for prostate cancer. Strahlenther Onkol. 2018 Jul;194(7):664-674. English. doi: 10.1007/s00066-018-1286-2. Epub 2018 Mar 9. PMID: 29523907.

1619

Poster Discussion

Multicenter approach to guide plan optimization of robotic intracranial SRS/SRT.

Laura Masi 1 , Valeria Landoni 2 , Sara Broggi 3 , Roberta Castriconi 3 , Marcello Serra 4 , Anna Stefania Martinotti 5 , Irene Redaelli 5 , Maria Cristina Frassanito 6 , Carmelo Siragusa 7 , Elena De Martin 8 , Raffaela Doro 1 , Antonella Soriani 2 , Alessia Tudda 3 , Antonella Del Vecchio 3 , Claudio Fiorino 3 1 IFCA, Department of Medical Physics and Radiation Oncology, Firenze, Italy. 2 IRCCS Regina Elena National Cancer Institute, Medical Physics Department, Roma, Italy. 3 IRCCS San Raffaele Scientific Institute, Medical Physics, Milano, Italy. 4 Istituto Nazionale Tumori—IRCCS—Fondazione G. Pascale, Department of Radiation Oncology, Napoli, Italy.