ESTRO 2024 - Abstract Book

S4792

Physics - Quality assurance and auditing

ESTRO 2024

2. Hansen CR, Jensen K, Smulders B, et al. Evaluation of decentralised model-based selection of head and neck cancer patients for a proton treatment study. DAHANCA 35. Radiother Oncol. 2023 Jul 20:109812.

3. Langendijk JA, Lambin P, De Ruysscher D, et al. Selection of patients for radiotherapy with protons aiming at reduction of side effects: The model-based approach. Radiotherapy and oncology. 2013;107(3):267-273.

4. Hansen CR, Friborg J, Jensen K, et al. NTCP model validation method for DAHANCA patient selection of protons versus photons in head and neck cancer radiotherapy. Acta Oncol. 2019 Oct;58(10):1410-1415.

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Digital Poster

Pre-treatment patient-specific quality assurance of Long Radiation Fields with Octavius ® 4D system

Mauro Buono 1 , Valerio Nardone 1 , Antonio Orientale 2 , Roberta Grassi 1 , Emma D'Ippolito 1 , Federico Gagliardi 1 , Vittorio Menditti 1 , Dino Rubini 1 , Salvatore Cappabianca 1 , Immacolata Pilotti 2 1 University of Campania “L. Vanvitelli", Department of Precision Medicine, Naples, Italy. 2 University Hospital "San Giovanni di Dio e Ruggi d'Aragona", Department of Diagnostic Imaging, Salerno, Italy

Purpose/Objective:

To validate a volume-modulated arc therapy (VMAT) quality assurance (QA) method developed for OCTAVIUS. 4D system (Oct4D) (PTW, Freiburg, Germany) for large radiation fields verification, such as typically characterizing craniospinal or gynecological treatments. Most of commercial systems for pretreatment patient specific QA (PSQA) doesn’t allow to cover dose distribution larger than 20X20 cm 2 . Nevertheless, the whole Octavius package has been recently redesigned to cover larger dimensions of the dose volume.

Material/Methods:

QA measurements were performed for 40 treatment plans (30 craniospinal, 9 gynecological, 1 soft-tissue sarcoma), generated using Monaco 5.51 (Elekta AB, Stockholm, Sweden) treatment planning system, using the cylindrical water equivalent phantom of Oct4D, equipped with the OCATVIUS. Detector 1500. The resulting planar dose distributions were evaluated in VeriSoft. 7.1 using gamma analysis with the criteria of 3%/3 mm. The same QA measurements were also performed with the standard method recommended by PTW and with radiochromic films and then compared to validate the procedure analyzed.

Results:

The long radiation field method results showed a pixel passing rate higher than 90% for each treatment plan. The standard method showed average differences between measured and calculated dose distributions using the criteria of 3%/3 mm: the passing rate was always lower than the percentage calculated for the long radiation field method