ESTRO 2024 - Abstract Book

S4753

Physics - Quality assurance and auditing

ESTRO 2024

The BN was successfully validated on an independent patient cohort in Poland. Furthermore, the external validation showed that a BN trained on the data from multiple centres outperformed BNs trained on data from single centres. Future steps include the construction of a BN applied to specific treatment modalities and tumour locations for the creation of a more robust model.

Keywords: AI, Quality Assurance, treatment planning

References:

1.PMID: 36925935

2. PMID: 30927253

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Digital Poster

In-situ recalibration of PTW STARCHECK detector array by measuring set of beam profiles

Andrei Tšižik, Vladimir Štšerbakov

North Estonia Medical Centre, Radiotherapy, Tallinn, Estonia

Purpose/Objective:

The STARCHECK (PTW-Freiburg) is a precise and reliable two-dimensional detector array for quality control and Linac beam adjustment measurements. However, for calibration verifying the detector array has to be sent to PTW for relative calibration.

In this work, we propose a quick method for checking the calibration factor of ionization chambers and performing required calibration factor correction (without sending detector array to the dedicated laboratory).

Material/Methods:

Figure 1 shows 7 points for measuring the profile of the transverse plane of the radiation beam (Varian Linac, 15MV, field size 25x25 cm, 100MU): 5 lateral positions close to central part of PTW STARCHECK array with step size 3 mm (lateral ±6 mm, ±3 mm, 0 mm) and 2 positions with lateral coordinates ±63 mm (Fig.1, A). As a result, the measurements of the central part of radiation beam give us a beam profile curve of 5 points for each detector (Fig.1, B). For example, detectors #40 and #41 have 5 measured points but four points with the same lateral coordinates are -3, -6, -9, -12 mm. In sum, the #41/ #40 readings ratio for these points provides us the #41/#40 sensitivities ratio we are looking for. Thus, by multiplying the found values and proceeding from one detector to