Consensus Guidelines for Implementing Pencil-Beam Scanning Proton Therapy for Thoracic Malignancies on Behalf of the PTCOG Thoracic and Lymphoma Subcommittee

Abstract

Pencil-beam scanning (PBS) proton therapy (PT), particularly intensity modulated PT, represents the latest advanced PT technology for treating cancers, including thoracic malignancies. On the basis of virtual clinical studies, PBS-PT appears to have great potential in its ability to tightly tailor the dose to the target while sparing critical structures, thereby reducing treatment-related toxicities, particularly for tumors in areas with complicated anatomy. However, implementing PBS-PT for moving targets has several additional technical challenges compared with intensity modulated photon radiation therapy or passive scattering PT. Four-dimensional computed tomography-based motion management and robust optimization and evaluation are crucial for minimizing uncertainties associated with beam range and organ motion. Rigorous quality assurance is required to validate dose delivery both before and during the course of treatment. Active motion management (eg, breath hold), beam gating, rescanning, tracking, or adaptive planning may be needed for cases involving significant motion or changes in motion or anatomy over the course of treatment.

Validation and clinical implementation of an accurate Monte Carlo code for pencil beam scanning proton therapy

“…Validation and clinical implementation of fast MC can potentially facilitate routine treatment plan quality assurance,18, 19 and bring 4D dynamic dose (4DDD) MC engines from conceptual research to clinical practices,20, 21, 22 when the dosimetric accuracy of analytical dose engines are challenged for the cases of heterogeneous tissue or with involvement of range shifter/patient bolus and large air gap.…”

“Patient‐specific validation of deformable image registration in radiation therapy: Overview and caveats”

“…An additional advantage of the use of DIR in a radiotherapy clinical workflow relies on the possibility of quantifying the actual distribution of radiation dose absorbed over the course of the treatment, by mapping the dose back to a common reference anatomy . Warping the dose grid to the reference anatomy according to the obtained deformation vector field (DVF), represents a widely used approach.…”

“…Warping the dose grid to the reference anatomy according to the obtained deformation vector field (DVF), represents a widely used approach. This solution has been adopted for dose accumulation, “dose of the day” from virtual CT and finally for 4D optimization strategies . For this latter, an alternative solution to dose warping consists in directly including the changes in anatomy in the delivered fluence, although this approach is not widely available for most commercial planning systems and still incorporate the use of a DVF …”

“…15,[33][34][35] An additional advantage of the use of DIR in a radiotherapy clinical workflow relies on the possibility of quantifying the actual distribution of radiation dose absorbed over the course of the treatment, by mapping the dose back to a common reference anatomy. 13,[36][37][38][39] Warping the dose grid to the reference anatomy according to the obtained deformation vector field (DVF), represents a widely used approach. This solution has been adopted for dose accumulation, 13,36,37 "dose of the day" from virtual CT [24][25][26]35,40,41,42 and finally for 4D optimization strategies.…”

“…38,39 For this latter, an alternative solution to dose warping consists in directly including the changes in anatomy in the delivered fluence, 41,[43][44][45][46][47] although this approach is not widely available for most commercial planning systems and still incorporate the use of a DVF. 39 Even if several algorithms have been developed for DIR and several applications rely on its use, the lack of gold standard and quantitative control metrics are slowing the transfer of DIR into the clinical workflow. A recent survey by Viergever et al 12 highlights that scientific research reached a milestone with DIR developments over the last 20 yr; however, several issues are not yet solved, especially for what concerns validation ( Fig.…”