![]() ![]() ![]() Analytical expressions for the determination of the MLC configuration parameters in the RayStation TPS were reported, but the method was applied only to the Millennium 120 and High Definition (HD120) Varian MLCs.Įlekta (Elekta AB, Stockholm, Sweden) linear accelerators (linacs) are also widely used in radiotherapy and all new Elekta linacs are equipped with the Agility MLC, which provides accurate and efficient IMRT treatments. The main concept behind this procedure is that the average dose in a region spanning several leaves can be used for characterizing and modeling fine details of the MLC such as the tongue‐and‐groove width and the leaf tip width. Hence, it is not surprising to find a large variability in the MLC modeling parameters used by the community, which raises concerns about the MLC models used in the clinic.įurthermore, it is well known that MLC parameters have a strong impact on IMRT/VMAT dose calculations, and considerable dose calculation errors are present in 17% of the institutions participating in IROC's external end‐to‐end audits.Ī novel procedure was recently proposed for standardizing the MLC configuration in TPSs using asynchronous sweeping gap (SG) tests and measurements with a Farmer‐type ion chamber. A wide variety of methods and detectors for commissioning are recommended by TPS manufacturers and in international guidelines.Īdditionally, plan‐specific quality assurance (PSQA) results obtained with commercial IMRT QA devices are often used for fine‐tuning the MLC model in the TPS despite many investigators having reported poor sensitivity of these devices to errors in the calculated doses. However, the MLC configuration process is challenging because it is not standardized. In this context, accurate modeling of the MLC in the TPS is essential to guarantee that the planned dose is delivered to the patients. In modern radiotherapy, treatment planning systems (TPSs) generate highly conformal dose distributions using intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT), in which the beam aperture is modulated by multileaf collimators (MLCs). ![]()
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