The Importance of Verification CT-QA Scans in Patients Treated with IMPT for Head and Neck Cancers

Abstract

Purpose To understand how verification computed tomography-quality assurance (CT-QA) scans influenced clinical decision-making to replan patients with head and neck cancer and identify predictors for replanning to guide intensity-modulated proton therapy (IMPT) clinical practice. Patients and Methods We performed a quality-improvement study by prospectively collecting data on 160 consecutive patients with head and neck cancer treated using spot-scanning IMPT who underwent weekly verification CT-QA scans. Kaplan-Meier estimates were used to determine the cumulative probability of a replan by week. Predictors for replanning were determined with univariate (UVA) and multivariate (MVA) Cox model hazard ratios (HRs). Logistic regression was used to determine odds ratios (ORs). P < .05 was considered statistically significant. Results Of the 160 patients, 79 (49.4%) had verification CT-QA scans, which prompted a replan. The cumulative probability of a replan by week 1 was 13.7% (95% confidence interval [CI], 8.82-18.9), week 2, 25.0% (95% CI, 18.0-31.4), week 3, 33.1% (95% CI, 25.4-40.0), week 4, 45.6% (95% CI, 37.3-52.8), and week 5 and 6, 49.4% (95% CI, 41.0-56.6). Predictors for replanning were sinonasal disease site (UVA: HR, 1.82, P = .04; MVA: HR, 3.64, P = .03), advanced stage disease (UVA: HR, 4.68, P < .01; MVA: HR, 3.10, P < .05), dose > 60 Gy equivalent (GyE; relative biologic effectiveness, 1.1) (UVA: HR, 1.99, P < .01; MVA: HR, 2.20, P < .01), primary disease (UVA: HR, 2.00 versus recurrent, P = .01; MVA: HR, 2.46, P = .01), concurrent chemotherapy (UVA: HR, 2.05, P < .01; MVA: not statistically significant [NS]), definitive intent treatment (UVA: HR, 1.70 versus adjuvant, P < .02; MVA: NS), bilateral neck treatment (UVA: HR, 2.07, P = .03; MVA: NS), and greater number of beams (5 beam UVA: HR, 5.55 versus 1 or 2 beams, P < .02; MVA: NS). Maximal weight change from baseline was associated with higher odds of a replan (≥3 kg: OR, 1.97, P = .04; ≥ 5 kg: OR, 2.13, P = .02). Conclusions Weekly verification CT-QA scans frequently influenced clinical decision-making to replan. Additional studies that evaluate the practice of monitoring IMPT-treated patients with weekly CT-QA scans and whether that improves clinical outcomes are warranted.

Air variability in maxillary sinus during radiotherapy for sinonasal carcinoma

“…Even though tendencies of patterns for aeration changes were present for the group of patients with increasing air in the maxillary sinus in F1–5, anatomy-based evaluation was shown not to be a successful strategy, and there is a need for development of other adaptive strategies. The need for adaption and re-planning is highlighted by a study by Evans et al [21] , who evaluated the influence of regular quality assurance CT on the frequency of re-planning during a proton treatment course. They found the sinonasal disease site to be a significant predictor for re-planning, and concluded that the quality assurance strategy affected the adaptive strategies.…”

Improving workflow for adaptive proton therapy with predictive anatomical modelling: A proof of concept

“…A relative biological effectiveness (RBE) of 1.1 for proton beams was used. The dosimetric goals and priorities for all plans in this study are summarised in Table 1 [4,[21][22][23]. Further details can be found in Appendix A.…”

Deformable CT image registration via a dual feasible neural network

“…7,8 In our clinic,we acquire a weekly QA CT for each head-and-neck (HN) cancer patient because tumor shrinkage is commonly observed. 9 The current practice is for the physicians to fuse the QA CT and the planning CT (pCT) using rigid/nonrigid registration to visualize any anatomical changes and then re-contour on the QA CT when large anatomical changes are observed. In these instances, new dose volume histograms (DVHs) are generated from the contoured CT QA images to quantify important dosimetric endpoints that guide the decision to continue with the current plan or replan.…”

“…Quality assurance (QA) CT scans can be regularly acquired in order to track the anatomical changes and assess the necessity of a replan to mitigate the aforementioned problems 7,8 . In our clinic, we acquire a weekly QA CT for each head‐and‐neck (HN) cancer patient because tumor shrinkage is commonly observed 9 . The current practice is for the physicians to fuse the QA CT and the planning CT (pCT) using rigid/nonrigid registration to visualize any anatomical changes and then re‐contour on the QA CT when large anatomical changes are observed.…”