ESTRO 2024 - Abstract Book

S4943

Physics - Quality assurance and auditing

ESTRO 2024

[4] Liu S, Bush KK, Bertini J, Fu Y, Lewis JM, Pham DJ, et al. Optimizing efficiency and safety in external beam radiotherapy using automated plan check (APC) tool and six sigma methodology. J Appl Clin Med Phys 2019;20:56– 64. https://doi.org/10.1002/acm2.12678.

[5] Covington EL, Chen X, Younge KC, Lee C, Matuszak MM, Kessler ML, et al. Improving treatment plan evaluation with automation. J Appl Clin Med Phys 2016;17:16–31. https://doi.org/10.1120/jacmp.v17i6.6322.

[6] Ford E, Conroy L, Dong L, de Los Santos LF, Greener A, Gwe-Ya Kim G, et al. Strategies for effective physics plan and chart review in radiation therapy: Report of AAPM Task Group 275. Med Phys 2020;47:e236–72. https://doi.org/10.1002/mp.14030.

3124

Digital Poster

Data mining to evaluate eight years of experience with a multiparametric normalization for lung SBRT

Stephanie Tanadini-Lang, Anja Kühnis, Lotte Wilke, Matthias Guckenberger

University Hospital Zurich, Department of Radiation Oncology, Zurich, Switzerland

Purpose/Objective:

There is a high variability in prescribed doses and normalization methods for stereotactic body radiation therapy (SBRT). Historically an inhomogeneous dose was prescribed to a certain isodoseline enclosing the planning target volume and the normalization was done on the maximum dose or a representative dose in the volume (in agreement with ICRU 50 [1]). The ICRU 91 report [2] for stereotactic treatments recommends prescribing and normalizing the dose to the isodose surface that covers an optimal percentage of the planning target volume (PTV). Independent of which normalization method is used, only one dosimetric value for the PTV or internal target volume (ITV) is fixed, which might lead to large variations in the other parameters dependent on the tumor volume or the tumor motion. To address this challenge, in January 2015, we introduced a multiparametric normalization method. In this study, we have harnessed data mining techniques to gather and analyze data from all patients treated using this method since 2015. Our goal was to assess the consistency and effectiveness of our multiparametric normalization approach.

Material/Methods:

In January 2015 the protocol for the multiparametric normalization method was released for peripheral lung tumors. The following goals for the PTV and ITV were implemented:

o >95% of the PTV covered with >100% of the prescribed dose o >95% of the ITV covered with >135% of the prescribed dose o A maximum dose inside the ITV between 152%-156% of the prescribed dose o A conformity index smaller than 1.2