ESTRO 2024 - Abstract Book

S3425

Physics - Dose calculation algorithms

ESTRO 2024

Statistical analysis consisted in descriptive statistics and Wilcoxon test for paired data (p<0.05), using the software SPSS.27 (IBM Corp., Armonk, NY, USA).

Results:

The replanning with VOLO TM Ultra showed a significant improvement in coverage compared to Volo Classic (V 95% = 95.8±1.9% vs 94.4±2.2%, p < 0.001) and hot spot in target (V 107%-PTV = 0.2±0.3 cc vs 1.2±1.4 cc, p= 0.002) for both the techniques. Moreover, while the dose to the OARs was comparable in TD, the TH plans showed lower dosimetric values for LAD (D mean = 4.4±1.5 Gy vs 5.6±2.3 Gy, p= 0.022), right breast (D mean = 2.1±0.7 Gy vs 2.7±1.1 Gy), left lung (D mean = 5.3±0.6 Gy vs 5.7±1.2 Gy; statistically different values for V 5Gy (p= 0.007) and V 40Gy (p= 0.017)) and also for hot spot in the body (V 107%-Body = 0.5±0.7 cc vs 1.3±3.4 cc, p= 0.012). The beam on time was comparable for the TD treatments (t= 168.6±18.1 sec vs 161.7±59.4 sec, p= 0.445) but slightly lower for TH VOLO TM Ultra plans (t= 381.7±54.6 sec vs 361.7±51.1 sec) even if not strictly statistically significant, (p= 0.114). Interestingly, starting from a standard script for the plan, the time required to obtain an acceptable plan was extremely shortened, thanks to the new fixed iteration process, that was approximately 3 min for TD and 5 min for TH, while in the Volo Classic optimization time was left to the operator and reasonably required a longer amount of time, especially for helical plans.

Conclusion:

The last upgrade of VOLO TM Ultra represents an important advance in optimization process of Radixact and Tomotherapy systems, as it allows to reach better quality standard, with better covererd target, reducing hot spot and improving dose to the organs. Moreover it allows time sparing in optimization processes.

Keywords: Dosimetry, Plan Quality, Efficiency

References:

White paper - VOLO TM Ultra Performance assessment and treatment plan quality for Radixact and TomoTherapy Delivery Sistems (2021) Accuray

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Digital Poster

Assessment of different methods of measuring the dosimetric leaf gap (DLG) for Varian TrueBeam HD.

Miguel A Diez, Francisco Clemente, Jose A Merino, Clara Navarro, Noelia Solis, Angel Forner, Paz Garcia de Acilu, Maria L Chapel

Hospital Universitario de Toledo, Radiofisica, Toledo, Spain