ESTRO 2024 - Abstract Book

S3245

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

References:

M. Miften et al., Tolerance limits and methodologies for IMRT measurement-based verification QA: Recommendations of AAPM Task Group No. 218, Med. Phys. 2018; 45: e53-e83

N. Dogan et al., AAPM Task Group Report 307: Use of EPIDs for Patient-Specific IMRT and VMAT QA, Med. Phys. 2023; 50: e865-e903

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Digital Poster

Preliminary experience in left breast breath-hold treatment with Hexamotion system.

Anna Sardo 1 , Nicola Padula 1 , Giorgio Bosticardo 1 , Simone Baroni 2 , Luca Frassinelli 2 , Rachele Petrucci 2 , Nicola Franza 3 , Alessia Reali 2 , Francesco Lucio 2 1 ASLCN2, Medical Physics, Verduno, Italy. 2 ASLCN2, Radiotherapy, Verduno, Italy. 3 Dosimetrica, Physics, Nocera Inferiore, Italy

Purpose/Objective:

The aim of this study is to assess the accuracy of a breath control device for breast cancer treatment with breath-hold technique. The device's ability to maintain consistent breath-hold patterns and the reproducibility of the respiratory waveform has been assessed for all treatment fractions.

Material/Methods:

Two patients with radiotherapy treatment on left breast volume and breath hold technique were selected. During the CT scan acquisition phase, the first patient showed good compliance in breath holding, whereas for the second patient, apnea was more difficult. Breath hold treatment for both patients was performed with Varian’s RGSC system (Respiratory Gating for Scanners). The treatments were performed with a mixed technique that involves the use of two tangential fields and a VMAT beam, with an arc amplitude equal to the angular distance between the two tangential fields. The treatment prescription is 40.5 Gy in 15 fractions. Two breath curves for the two patients, free breath, and breath hold, were imported into the Hexamotion system and were used to acquire CT images of the Delta4 phantom. A further CT scan of the Delta4 phantom not moving (motionless) was carried out to assess the accuracy of the plan. The treatment plan of the two patients was recalculated on the three scans obtained and an ROI on the 50% isodose was created with a crop of 1 cm with respect to the body, to simulate a breast target. For all the 15 fractions the breath profile of the two patients, acquired beam by beam during treatments, was used during the measurements. Gamma evaluation was performed using tolerance limit of 3% for dose, 2mm for DTA and a threshold of 10%.