Comprehensive quality control process for high precision intensity modulated adaptive proton therapy

The thesis focuses on development and clinical implementation of comprehensive and overlaying quality control process aimed at supporting introduction of high precision adaptive IMPT workflows. The thesis consists of seven chapters, covering topics on quality control for proton range accuracy, reconstruction, and accumulation of delivered dose distributions longitudinally throughout the proton therapy course and independent dose recalculation/predictive outcome-based patient specific quality assurance procedures. A proton range probing method as a quality control tool for range accuracy validation has been proposed and applied for range accuracy assessments in animal tissue samples covering a broad range of tissue types. A fraction-wise 4D dose reconstruction and accumulation procedure utilizing treatment delivery log files and patient-specific daily breathing patterns has been proposed and implemented in clinical practice. Validation of the procedure in controlled conditions with a 4D phantom revealed ability to spatially reconstruct the dose distributions with submillimeter accuracy. Eventually, an alternative approach for in-beam measurement-based patient specific quality assurance (PSQA) procedure has been investigated, developed, and introduced in clinical practice. By incorporating the developed range probing QC procedure as a validation tool for synthetic CTs and utilizing developed dose reconstruction and accumulation workflow, it enables possibility to establish a comprehensive longitudinal patient specific quality control process to monitor the treatment delivery in an environment of adaptive proton therapy. Introduction of more adaptive treatment procedures and availability of online adaptive workflows in proton therapy might be the next major advancement needed to take full advantage of the physical characteristics of the proton beam

Technical Note: 4D cone-beam CT reconstruction from sparse-view CBCT data for daily motion assessment in pencil beam scanned proton therapy (PBS-PT)

Purpose: The number of pencil beam scanned proton therapy (PBS-PT) facilities equipped with cone-beam computed tomography (CBCT) imaging treating thoracic indications is constantly rising. To enable daily internal motion monitoring during PBS-PT treatments of thoracic tumors, we assess the performance of Motion-Aware RecOnstructiOn method using Spatial and Temporal Regularization (MA-ROOSTER) four-dimensional CBCT (4DCBCT) reconstruction for sparse-view CBCT data and a realistic data set of patients treated with proton therapy. Methods: Daily CBCT projection data for nine non-small cell lung cancer (NSCLC) patients and one SCLC patient were acquired at a proton gantry system (IBA Proteus® One). Four-dimensional CBCT images were reconstructed applying the MA-ROOSTER and the conventional phase-correlated Feldkamp-Davis-Kress (PC-FDK) method. Image quality was assessed by visual inspection, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and the structural similarity index measure (SSIM). Furthermore, gross tumor volume (GTV) centroid motion amplitudes were evaluated. Results: Image quality for the 4DCBCT reconstructions using MA-ROOSTER was superior to the PC-FDK reconstructions and close to FDK images (median CNR: 1.23 [PC-FDK], 1.98 [MA-ROOSTER], and 1.98 [FDK]; median SNR: 2.56 [PC-FDK], 4.76 [MA-ROOSTER], and 5.02 [FDK]; median SSIM: 0.18 [PC-FDK vs FDK], 0.31 [MA-ROOSTER vs FDK]). The improved image quality of MA-ROOSTER facilitated GTV contour warping and realistic motion monitoring for most of the reconstructions. Conclusion: MA-ROOSTER based 4DCBCTs performed well in terms of image quality and appear to be promising for daily internal motion monitoring in PBS-PT treatments of (N)SCLC patients

Comprehensive quality control process for high precision intensity modulated adaptive proton therapy

The thesis focuses on development and clinical implementation of comprehensive and overlaying quality control process aimed at supporting introduction of high precision adaptive IMPT workflows. The thesis consists of seven chapters, covering topics on quality control for proton range accuracy, reconstruction, and accumulation of delivered dose distributions longitudinally throughout the proton therapy course and independent dose recalculation/predictive outcome-based patient specific quality assurance procedures. A proton range probing method as a quality control tool for range accuracy validation has been proposed and applied for range accuracy assessments in animal tissue samples covering a broad range of tissue types. A fraction-wise 4D dose reconstruction and accumulation procedure utilizing treatment delivery log files and patient-specific daily breathing patterns has been proposed and implemented in clinical practice. Validation of the procedure in controlled conditions with a 4D phantom revealed ability to spatially reconstruct the dose distributions with submillimeter accuracy. Eventually, an alternative approach for in-beam measurement-based patient specific quality assurance (PSQA) procedure has been investigated, developed, and introduced in clinical practice. By incorporating the developed range probing QC procedure as a validation tool for synthetic CTs and utilizing developed dose reconstruction and accumulation workflow, it enables possibility to establish a comprehensive longitudinal patient specific quality control process to monitor the treatment delivery in an environment of adaptive proton therapy. Introduction of more adaptive treatment procedures and availability of online adaptive workflows in proton therapy might be the next major advancement needed to take full advantage of the physical characteristics of the proton beam