scholarly journals Impact of respiratory motion on worst-case scenario optimized intensity modulated proton therapy for lung cancers

2015 ◽  
Vol 5 (2) ◽  
pp. e77-e86 ◽  
Author(s):  
Wei Liu ◽  
Zhongxing Liao ◽  
Steven E. Schild ◽  
Zhong Liu ◽  
Heng Li ◽  
...  
Keyword(s):  
Proton Therapy ◽  
Respiratory Motion ◽  
Case Scenario ◽  
Worst Case ◽  
Lung Cancers ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated ◽  
Worst Case Scenario

scholarly journals CBCT-Based Adaptive Assessment Workflow for Intensity Modulated Proton Therapy for Head and Neck Cancer

2021 ◽  
Author(s):  
Mariluz De Ornelas ◽  
Yihang Xu ◽  
Kyle Padgett ◽  
Ryder M. Schmidt ◽  
Michael Butkus ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Head And Neck ◽  
Proton Therapy ◽  
Case Scenario ◽  
Worst Case ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated ◽  
Worst Case Scenario ◽  
Patient Setup ◽  
Delivered Dose

Abstract Purpose Anatomical changes and patient setup uncertainties during intensity modulated proton therapy (IMPT) of head and neck (HN) cancers demand frequent evaluation of delivered dose. This work investigated a cone-beam computed tomography (CBCT) and deformable image registration based therapy workflow to demonstrate the feasibility of proton dose calculation on synthetic computed tomography (sCT) for adaptive IMPT treatment of HN cancer. Materials and Methods Twenty-one patients with HN cancer were enrolled in this study, a retrospective institutional review board protocol. They had previously been treated with volumetric modulated arc therapy and had daily iterative CBCT. For each patient, robust optimization (RO) IMPT plans were generated using ±3 mm patient setup and ±3% proton range uncertainties. The sCTs were created and the weekly delivered dose was recalculated using an adaptive dose accumulation workflow in which the planning computed tomography (CT) was deformably registered to CBCTs and Hounsfield units transferred from the planning CT. Accumulated doses from ±3 mm/±3% RO-IMPT plans were evaluated using clinical dose-volume constraints for targets (clinical target volume, or CTV) and organs at risk. Results Evaluation of weekly recalculated dose on sCTs showed that most of the patient plans maintained target dose coverage. The primary CTV remained covered by the V95 > 95% (95% of the volume receiving more than 95% of the prescription dose) worst-case scenario for 84.5% of the weekly fractions. The oral cavity accumulated mean dose remained lower than the worst-case scenario for all patients. Parotid accumulated mean dose remained within the uncertainty bands for 18 of the 21 patients, and all were kept lower than RO-IMPT worst-case scenario for 88.7% and 84.5% for left and right parotids, respectively. Conclusion This study demonstrated that RO-IMPT plans account for most setup and anatomical uncertainties, except for large weight-loss changes that need to be tracked throughout the treatment course. We showed that sCTs could be a powerful decision tool for adaptation of these cases in order to reduce workload when using repeat CTs.

SU-E-T-452: Impact of Respiratory Motion On Robustly-Optimized Intensity-Modulated Proton Therapy to Treat Lung Cancers

2014 ◽  
Vol 41 (6Part18) ◽  
pp. 330-330
Author(s):  
W Liu ◽  
Z Liao ◽  
S Schild ◽  
P Park ◽  
H Li ◽  
...  
Keyword(s):  
Proton Therapy ◽  
Respiratory Motion ◽  
Lung Cancers ◽  
Intensity Modulated Proton Therapy ◽  
Intensity Modulated

scholarly journals A Critical Review of LET-Based Intensity-Modulated Proton Therapy Plan Evaluation and Optimization for Head and Neck Cancer Management

2021 ◽  
Vol 8 (1) ◽  
pp. 36-49
Author(s):  
Wei Deng ◽  
Yunze Yang ◽  
Chenbin Liu ◽  
Martin Bues ◽  
Radhe Mohan ◽  
...  
Keyword(s):  
Robust Optimization ◽  
Head And Neck ◽  
Proton Therapy ◽  
Worst Case ◽  
Plan Evaluation ◽  
Intensity Modulated Proton Therapy ◽  
Cancer Management ◽  
Intensity Modulated ◽  
The Impact ◽  
Analytical Approaches

Abstract In this review article, we review the 3 important aspects of linear-energy-transfer (LET) in intensity-modulated proton therapy (IMPT) for head and neck (H&N) cancer management. Accurate LET calculation methods are essential for LET-guided plan evaluation and optimization, which can be calculated either by analytical methods or by Monte Carlo (MC) simulations. Recently, some new 3D analytical approaches to calculate LET accurately and efficiently have been proposed. On the other hand, several fast MC codes have also been developed to speed up the MC simulation by simplifying nonessential physics models and/or using the graphics processor unit (GPU)–acceleration approach. Some concepts related to LET are also briefly summarized including (1) dose-weighted versus fluence-weighted LET; (2) restricted versus unrestricted LET; and (3) microdosimetry versus macrodosimetry. LET-guided plan evaluation has been clinically done in some proton centers. Recently, more and more studies using patient outcomes as the biological endpoint have shown a positive correlation between high LET and adverse events sites, indicating the importance of LET-guided plan evaluation in proton clinics. Various LET-guided plan optimization methods have been proposed to generate proton plans to achieve biologically optimized IMPT plans. Different optimization frameworks were used, including 2-step optimization, 1-step optimization, and worst-case robust optimization. They either indirectly or directly optimize the LET distribution in patients while trying to maintain the same dose distribution and plan robustness. It is important to consider the impact of uncertainties in LET-guided optimization (ie, LET-guided robust optimization) in IMPT, since IMPT is sensitive to uncertainties including both the dose and LET distributions. We believe that the advancement of the LET-guided plan evaluation and optimization will help us exploit the unique biological characteristics of proton beams to improve the therapeutic ratio of IMPT to treat H&N and other cancers.

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