Update on yesterday’s dose—Use of delivery log-files for daily adaptive proton therapy (DAPT)

Abstract

In daily adaptive proton therapy (DAPT), the treatment plan is re-optimized on a daily basis. It is a straightforward idea to incorporate information from the previous deliveries during the optimization to refine this daily proton delivery. A feedback signal was used to correct for delivery errors and errors from an inaccurate dose calculation used for plan optimization. This feedback signal consisted of a dose distribution calculated with a Monte Carlo algorithm and was based on the spot delivery information from the previous deliveries in the form of log-files. We therefore called the method Update On Yesterday’s Dose (UYD). The UYD method was first tested with a simulated DAPT treatment and second with dose measurements using an anthropomorphic phantom. For both, the simulations and the measurements, a better agreement between the delivered and the intended dose distribution could be observed using UYD. Gamma pass rates (1%/1 mm) increased from around 75% to above 90%, when applying the closed-loop correction for the simulations, as well as the measurements. For a DAPT treatment, positioning errors or anatomical changes are incorporated during the optimization and therefore are less dominant in the overall dose uncertainty. Hence, the relevance of algorithm or delivery machine errors even increases compared to standard therapy. The closed-loop process described here is a method to correct for these errors, and potentially further improve DAPT.

Dosimetric influence of deformable image registration uncertainties on propagated structures for online daily adaptive proton therapy of lung cancer patients

“…The daily DVHs should then be evaluated with these offline corrected structures. If major differences between the delivered and the desired dose distributions and DVHs are found, these could then be corrected for in a feedback loop during the next fraction, in a similar way to that described by Matter et al [69]. Manually corrected structures can be used as the reference for the next fractions.…”

CT-on-Rails Versus In-Room CBCT for Online Daily Adaptive Proton Therapy of Head-and-Neck Cancers

“…One adaptation workflow is based on fast GPU Monte Carlo dose calculation and Cone-Beam CT (CBCT) imaging [ 8 , 9 ]. Alternatively, an approach based on in-room CT imaging and analytical dose recalculation has been proposed [ 10 , 11 , 12 , 13 ]. In terms of different dose calculation methods, analytical computations are faster, but Monte Carlo dose calculation has been shown to increase accuracy in proton therapy significantly [ 14 ].…”

A fast analytical dose calculation approach for MRI-guided proton therapy

“…However, uncertainties due to motion (Duetschler et al 2023) and anatomical changes (Nenoff et al 2020) are expected to be much larger than the discrepancies seen here. Additionally, and as described by Nenoff et al (2021) for their online adaptive proton therapy workflow, independent offline MC re-calculations could be used for quality assurance and final dose accumulation purposes (Winterhalter et al 2018, 2019b, Matter et al 2020.…”