ESTRO meets Asia 2024 - Abstract Book

S4

Invited Speaker

ESTRO meets Asia 2024

• To showcase examples of how extended/expanded/advanced practice of RTTs can contribute to a more integrated and personalized patient-centred care approach

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Brachytherapy with intracavitary-interstitial applicators

Supriya Chopra

Radiation Oncology, ACTREC, Tata Memorial Centre, Homi Bhabha National Institute, Navi Mumbai, India

Abstract

In this teaching lecture the evolution of intracavitary and interstitial brachytherapy techniques for cervical cancer and clinical outcomes will be discussed. Speaker will be discussing expert tips and tricks for treatment planning and how to adapt these applicators for clinically challenging and complex cases including gynaecological reirradiation.

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Commissioning of applicators

Jeevanshu Jain

Department of Radiation Oncology, ACTREC, Tata Memorial Centre, Homi Bhabha National Institute, Navi Mumbai, India

Abstract

Image-guided brachytherapy (IGBT) necessitates accurate applicator reconstruction and contouring to achieve successful outcomes. Deviations in dose-volume histogram (DVH) parameters for targets and organs at risk (OARs) have been noted due to uncertainties in applicator reconstruction. While random errors can be minimized by reducing image slice thickness, systematic errors require robust quality assurance of the afterloader, treatment planning system, imaging procedures, and brachytherapy applicators. Comprehensive applicator commissioning plays a critical role in mitigating these systematic errors, thereby reducing uncertainties in DVH parameters. Applicator commissioning involves validating the applicator geometry against the vendor's design and ensuring its clinical suitability. The applicator commissioning process includes (i) physical verification, (ii) offset calculation, (iii) imaging artifact evaluation, (iv) verification of source dwell positions relative to the applicator geometry, and (v) establishing a standard loading pattern for the applicators. Physical verification entails visual inspection for damage and ensuring dimensional integrity (the length, diameter and angulation of various applicator components) using tools like rulers, calipers, and gauges. Radiographs or CT scans can confirm the applicator's structural integrity.

Autoradiography, using radiochromic films, is essential for offset calculation and dwell position verification, ensuring alignment between vendor-specified offsets and actual measurements.