RTsafe and Elekta conduct the world's first experimental demonstration of a clinical radiotherapy plan quasi real-time dose deposition at ASTRO 2019

30 Sep 2019

A research collaboration between RTsafe and Elekta resulted to the world’s first experimental quasi-real-time demonstration of dose accumulation during a clinical IMRT irradiation, a true breakthrough in radiotherapy. The methodology and preliminary results were recently presented at ASTRO 2019 in Chicago.

For the purposes of this study, specially designed PseudoPatient™ head phantoms filled with polymer gel, suitable for 3D relative dosimetry, were used. RTsafe's PseudoPatient™ phantoms provide a realistic contrast of bone structures and soft tissue in both CT and MR imaging. The scientific team of RTsafe developed the pulse sequences by fine tuning the parameters of the MRI scanner of the Unity system that allowed the acquisition of real-time MR images of the phantom during irradiation. The acquired MR dataset was processed immediately after irradiation and converted into 3D dose matrix. 

With this methodology, not only can Elekta Unity users see the soft tissue during irradiation but they can also see the actual dose accumulation as the irradiation process is being implemented in a phantom geometry. Please note that Lee et al. (2018) have presented analogous results but just for simple square fields irradiating simple geometry phantoms (see footnote). Apart from its significance as a proof of a dose deposition process on a passive dosimeter, this methodology offers an excellent tool for commissioning and periodic QA for MR-linacs, quantitative relative 3D dosimetry End-to-End QA, as well as, training and confidence building for UNITY users.
 

View the full presentation here:
Clinical IMRT Irradiation with an MR-Linac System: - A Methodology and Preliminary Results for a Real-Time Verification of Spatial Accuracy of Dose Delivery (E. Pappas, G. Kalaitzakis, C. Paraskevopoulou, I. Seimenis, E. P. Pappas, and T. G. Maris).  A full article is under review at the PMB journal.

To view the presented video on experimental demonstration of dose delivery during irradiation (shown at slide #10 of the above presentation), click here.


Footnote:
H.J. Lee, M. Kadbi, G. Bosco, G. S. Ibbott, Real-time volumetric relative dosimetry for magnetic resonance—image-guided radiation therapy (MR-IGRT), Phys. Med. Biol. 63 (2018) 04, 5021