Performance evaluation of Monaco radiotherapy treatment planning system using CIRS Thorax Phantom: Dosimetric assessment of flattened and non-flattened photon beams

Abstract

Aim: The present study was undertaken to evaluate the performance of different algorithms for flattening filter-free (FFF) and flattened (FF) photon beams in three different in-homogeneities. Materials and Method: Computed tomography (CT) image sets of the CIRS phantom maintained in the SAD setup by placing the ionization chamber in the lung, bone, and tissue regions, respectively, were acquired. The treatment planning system (TPS) calculated and the ionization chamber measured the doses at the center of the chamber (in the three mediums) were recorded for the flattened and non-flattened photon beams. Results: The results were reported for photon energies of 6 MV, 10 MV, 15 MV, 6 FFF, and 10 FFF of field sizes 5 × 5 cm2, 10 × 10 cm2, and 15 × 15 cm2. In the bone inhomogeneity, the pencil beam algorithm predicted that the maximum dose variation was 4.88% of measured chamber dose in 10-MV photon energy for the field size 10 × 10 cm2. In water inhomogeneity, both the collapsed cone and Monte Carlo algorithm predicted that the maximum dose variation was ± 3% of measured chamber dose in 10-MV photon energy for the field size 10 × 10 cm2 and in 10-MV FFF photon energy for the field size 5 × 5 cm2, whereas in lung inhomogeneity, the pencil beam algorithm predicted that the highest dose variation was - 6.9% of measured chamber dose in 10-MV FFF photon energy for the field size 5 × 5 cm2. Conclusion: FF and FFF beams performed differently in lung, water, and bone mediums. The assessment of algorithms was conducted using the anthropomorphic phantom; therefore, these findings may help in the selection of appropriate algorithms for particular clinical settings in radiation delivery.

Evaluating the performance of automated external contouring tool on dose calculation of treatment planning system

“…As mentioned above, since MC is based on transporting each particle, it is known as the most accurate algorithm for dose calculation and will be used in this study. 13 In order to verify the QA of the Monaco TPS, the guidelines described in TECDOC-1583 of International Atomic Energy Agency (IAEA) including acceptance, commissioning and QA testing were performed (Table 1). 14 At the onset of the study, the Electron Density phantom model 062M known as CT-ED phantom and Thorax phantom Model 002LFC, both from CIRS company (CIRS Co., USA), were scanned by GE 16 slices CT scanner with 110 kVp energy and slice thickness of 1 mm (Fig.…”

“…As mentioned above, since MC is based on transporting each particle, it is known as the most accurate algorithm for dose calculation and will be used in this study. 13…”