Dosimetric Validation of Treatment Planning System for Conventional Linac and 1.5 T Mr-Linac

Year 2025, Volume: 6 Issue: 1, 372 - 385, 30.06.2025

Uğur Akbayirli , Halil Arslan

https://doi.org/10.53501/rteufemud.1581517

Abstract

This study aims to validate and compare the Monte Carlo (MC) beam modeling of the Monaco treatment planning system (TPS) for both conventional linear accelerator (linac) and 1.5 T MR-linac systems. It was evaluated the accuracy of beam profile and percentage depth dose (PDD) calculations by Monaco TPS for various photon energies and field sizes. Measurements of beam profiles and PDD were conducted using a water phantom and detectors for both systems. The Monaco TPS calculations, using MC algorithms, were compared with the corresponding measured data. Gamma analysis was used to assess the agreement between calculated and measured dose distributions. Results demonstrated a high level of agreement for both systems. For the conventional linac, gamma passing rates were above 95% for dose difference (DD) 2% and distance to agreement (DTA) 2 mm in most cases, with some instances in the 85-95% range. For the 1.5 T MR-linac, gamma passing rates were generally above 95% for DD 2% and DTA 2 mm. However, with stricter criteria of DD 1% and DTA 1 mm, certain measurements, particularly in the inline direction at gantry 0° and at gantry 270°, yielded passing rates below 95%. The Monaco TPS demonstrates good accuracy in dose calculations for both systems. The study emphasizes the importance of validating beam modeling in TPS, especially for MR-linac systems where the magnetic field can affect dose distributions. Further research is recommended to improve the modeling of magnetic field effects and enhance dose calculation accuracy in specific scenarios.

Keywords

Mr-linac , Linac , Tps , dosimetric , radiation therapy

Konvansiyonel Linak ve 1,5 T Mr-Linak için Tedavi Planlama Sisteminin Dozimetrik Doğrulaması

Abstract

Bu çalışma, Monaco tedavi planlama sisteminin (TPS) Monte Carlo (MC) ışın modellemesini konvansiyonel lineer hızlandırıcı (linak) ve 1,5 T MR-linak sistemlerinde doğrulamayı ve karşılaştırmayı amaçlamaktadır. Çalışma, Monaco TPS tarafından farklı foton enerjileri ve alan boyutları için yapılan ışın profili ve yüzde derinlik dozu (PDD) hesaplamalarının doğruluğunu değerlendirmektedir. Hem konvansiyonel linak hem de 1,5 T MR-linak sistemleri için su fantomu ve dedektörler kullanılarak ışın profili ve PDD ölçümleri yapılmıştır. Monaco TPS hesaplamaları, MC algoritmaları kullanılarak ölçülen verilerle karşılaştırılmıştır. Hesaplanan ve ölçülen doz dağılımları arasındaki uyumu değerlendirmek için gamma analizi yapılmıştır. Sonuçlar, her iki sistem için de yüksek derecede uyum göstermiştir. Konvansiyonel linak için, gamma geçiş oranları çoğu durumda doz farkı (dose difference, DD) %2 ve uzaklık uyumu (distance to agreement, DTA) 2 mm için %95'in üzerindedir, bazı durumlarda ise %85-95 aralığındadır. 1,5 T MR-linak için, gamma geçiş oranları genellikle DD %2 ve DTA 2 mm için %95'in üzerindedir. Ancak, daha hassas DD %1 ve DTA 1 mm kriterleri kullanıldığında, özellikle inline doğrultuda gantri 0° ve gantri 270°'de yapılan ölçümlerde geçiş oranları %95'in altına düşmüştür. Monaco TPS, her iki sistem için de doz hesaplamalarında iyi bir doğruluk sergilemektedir. Çalışma, özellikle manyetik alanın doz dağılımlarını etkileyebileceği MR-linak sistemleri için TPS'de ışın modellemesini doğrulamanın önemini vurgulamaktadır. Manyetik alan etkilerinin modellenmesini iyileştirmek ve belirli senaryolarda doz hesaplama doğruluğunu artırmak için daha fazla araştırma yapılması gerekmektedir.

Keywords

Mr-Linak , Linak , TPS , Dozimetrik , Radyasyon Terapisi

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