التفاصيل البيبلوغرافية
| العنوان: |
Evaluation of the timing and quality of a reference beam model-based “short” commissioning. |
| المؤلفون: |
Reggiori, Giacomo, Fauci, Francesco La, Gallo, Pasqualina, Paganini, Lucia, Lobefalo, Francesca, Bresolin, Andrea, Mancosu, Pietro, Navarria, Pierina, Clerici, Elena, Bellu, Luisa, Scorsetti, Marta, Tomatis, Stefano |
| المصدر: |
Journal of Radiosurgery & SBRT; 2022 Supplement, Vol. 8, p10-10, 2/3p |
| مصطلحات موضوعية: |
IONIZATION chambers, DETECTORS |
| مستخلص: |
Purpose and objective: Commissioning measurements are time-consuming and require high precision in execution. Reference Beam Models (RBM) consist of predefined Pencil Beam and Monte Carlo dose profiles that may dramatically reduce the number of measurements necessary to commission a beam. The purpose of this work was to evaluate the accuracy and robustness of using the RBMs offered by BrainLab®(Munich, Germany) with the treatment planning system (TPS) Elements® for multiple brain metastases. Materials and method: The 6MV and 10MVFFF beams of a TrueBeamSTX Linac were considered. The Linac was equipped with a HD120 MultiLeafCollimator (MLC) whose central leaves have a width of 2.5mm at isocenter. A Beamscan water tank (PTW, Freiburg, Germany) was used with a SSD=900. Absolute dose was measured at isocenter with a Farmer-type calibrated ion chamber for a 10x10cm2 field. Profiles and PDDs were measured for 4 different MLC-defined square fields ranging from 5x5 to 220x220mm2. Output Factors were measured for the same fields and in the same set-up. A PTW MicroDiamond detector and a 0.125cc PTW Semiflex 3D ion chamber were used for all measurements. A comparison between these measurements and calculations performed in a virtual water phantom with MC-Elements and Acuros algorithms were performed. Once the TPS was configured, some “simple” plans (i.e. without MLC) and 5 patients were planned with the Multiple Brain Metastases module and delivered. The dose distribution was verified with three different methods. The 2D fluence distribution was evaluated with Portal Dosimetry. The log-file reconstructed 3D dose distribution was evaluated with an indipendent algorithm (M3D, Mobius). The measured 3D dose distribution was evaluated with the octavius detector. Results: The total time required for the commissioning measurements was less than 6 hours. The best agreement between measured and modeled values both for OFs and profiles was obtained selecting a spot size of 0.4mm and 0.Xmm for 6MV and 10MVFFF beams respectively (figure 1). Calculated OFs were within 1.6% for all field sizes except for the 5x5mm were it was 4.8% (figure 2). The 3%-3mm 3DGamma >96.3% (96.3%-99.8%) for the “simple” plans. Gamma values for the 5 clinical plans were 99.5%-100% for Portal Dosimetry, 99.8%-100% for the M3D calculation and 97.3%-99.1% for the Octavius4D measurements. Conclusion: Machine commissioning times are dramatically reduced and compatible with clinical practice. The configuration and selection of the RBM is simple and intuitive. Good agreement between measured and calculated dose distributions was observed down to very small field sizes. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
Complementary Index |
