ESTRO 2024 - Abstract Book

S3473

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

ESTRO 2024

CAA. PTV coverage is prioritised in the planning process, therefore it is not always possible to achieve CAA maximum dose <20Gy. In cohort 1 63% of cases have 1cc max dose to CAA > 20Gy, reduced to 30% in cohort2.

Whole heart V30Gy is also generally lower in cohort 2, with V30Gy reduced from median 10.3% to 8.0% (P=0.002). Little change was seen in the dose statistics for other OARs. Lungs-ITV mean dose increased from median 10.1Gy to 10.2Gy after introduction of the CAA max dose objective (P=0.65), and Lungs-PTV V20Gy reduced from median 16.6% to 16.4% (P=0.72). Oesophagus mean dose increased marginally from median 12.2Gy to 12.9Gy (P=0.26).

Conclusion:

A Cardiac Avoidance Area has been introduced as a new OAR for planning of lung radiotherapy treatments at our centre. After the introduction of a dose limit to the base of the heart, mean and maximum dose to the CAA and whole heart was reduced significantly, with little change observed in doses to other OARs. Clinical outcomes following the introduction of CAA sparing lung RT will be analysed using a real-world data methodology as part of the RAPID-RT study [4].

Keywords: cardiac dose, heart substructures, OAR doses

References:

[1] A. McWilliam, J. Kennedy, C. Hodgson, E. Vasquez Osorio, C. Faivre-Finn, and M. van Herk, “Radiation dose to heart base linked with poorer survival in lung cancer patients,” Eur J Cancer, vol. 85, pp. 106–113, Nov. 2017, doi: 10.1016/J.EJCA.2017.07.053. [2] A. McWilliam, A. Abravan, K. Banfill, C. Faivre-Finn, and M. van Herk, “Demystifying the Results of RTOG 0617: Identification of Dose Sensitive Cardiac Subregions Associated With Overall Survival,” Journal of Thoracic Oncology, vol. 18, no. 5, pp. 599–607, May 2023, doi: 10.1016/j.jtho.2023.01.085. [3] A. McWilliam et al., “Novel Methodology to Investigate the Effect of Radiation Dose to Heart Substructures on Overall Survival,” Int J Radiat Oncol Biol Phys, vol. 108, no. 4, pp. 1073–1081, Nov. 2020, doi: 10.1016/J.IJROBP.2020.06.031.

[4] G. Price et al., “Can Real-world Data and Rapid Learning Drive Improvements in Lung Cancer Survival? The RAPID-RT Study,” Clin Oncol, vol. 34, no. 6, pp. 407–410, Jun. 2022, doi: 10.1016/j.clon.2021.12.017.

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0 mm PTV margin to reduce toxicity in MRI-guided RT for favorable intermediate-risk prostate cancer

Mathijs G Dassen 1 , Alison C Tree 2 , Ben Neijndorff 1 , Peter De Ruiter 1 , Rens Van Haveren 1 , Thyrza Jagt 1 , Joeke Van Der Linden 1 , Lisa Wiersema 1 , Adam Mitchell 2 , Alex Dunlop 2 , Dylan Breitkreutz 3 , Floris J Pos 1 , Tomas Janssen 1 , Danny Vesprini 3 , Uulke A Van Der Heide 1