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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.

Management of recurrent/persistent Head and Neck Cancers is a major challenge for the radiation oncologist. Current rate of locoregional recurrence for head and neck cancers is 40-50%. The primary salvage modality for resectable cases is surgery often followed by adjuvant chemo-radiotherapy. Traditional postoperative radiation therapy is 50-60 Gy delivered 5-6 week after surgery. There are numerous pitfalls of this practice: uncertainty of clinical target volume, tumor cell proliferation during waiting period, and inconvenience of six weeks travel to the department of radiation therapy, to name a few. Intraoperative radiation therapy (IORT) has been shown to be a great help in addressing some of these concerns. Greater accuracy of target volume at the time of surgery, avoidance of cell proliferation during the waiting period, and elimination or reduction in visits to the department of radiation oncology are some of its advantages. Modern IORT is based on the availability of mobile linear accelerators capable of delivering high dose of radiation in one fraction to a defined volume at the time of surgery. Most of the literature is on the use of remote after-loading catheters and/or electron beams. Purpose/Objective(s): Hereby we report the first experience of using INTRABEAM IORT (Zeiss Corporation, Mannheim, Germany) in treating recurrent head and neck cancers. The system is based on delivering a high dose of low-energy (50 keV) X-rays in one fraction at the time of surgery. To our knowledge this is the first report of using this system in recurrent head and neck cancer setting. Materials/Methods: From March 2014 to 2016 we have treated 22 patients with recurrent or advanced head and neck cancers with IntraBeam device. Of these seven patients had primary parotid tumors and the rest were either recurrent at the parotid site or in the neck. IORT dose, prescribed to 5 mm depth, was either 5Gy boost or 12-14 Gy definitive dose. We have used FLAT applicators in size ranging from 4-6 cm in diameter. 10 of 22 patients also had 40-50 Gy external beam radiation therapy, based on permanent pathological findings. Results: With a median follow up of 16 months (range: 3-33 months) IORT in-field local control was achieved in 19 of 22 patients with two additional patient follow up while tumor was under control. Complications included wound healing(1 patient), fat necrosis(1 patient), and two patients with radiation induced neuropathies. Conclusion: Our preliminary data suggest that a high dose of IORT with low energy (50 keV) X-rays is a safe and effective alternative to conventional treatment modalities. Detailed data will be presented. To our knowledge this is the first reported use of INTRABEAM IORT in recurrent head and neck cancer patients.

Purpose Finite proton range affords improved dose conformality of radiation therapy when patient regions-of-interest geometries are well characterized. Substantial changes in patient anatomy necessitate re-planning (RP) to maintain effective, safe treatment. Regularly planned verification scanning (VS) is performed to ensure consistent treatment quality. Substantial resources, however, are required to conduct an effective proton plan verification program, which includes but is not limited to, additional computed tomography (CT) scanner time and dedicated personnel: radiation therapists, medical physicists, physicians, and medical dosimetrists. Materials and Methods Verification scans (VSs) and re-plans (RPs) of 711 patients treated with proton therapy between June 2015 and June 2018 were studied. All treatment RP was performed with the intent to maintain original plan integrity and coverage. The treatments were classified by anatomic site: brain, craniospinal, bone, spine, head and neck (H&N), lung or chest, breast, prostate, rectum, anus, pelvis, esophagus, liver, abdomen, and extremity. Within each group, the dates of initial simulation scan, number of VSs, number of fractions completed at the time of VS, and the frequency of RP were collected. Data were analyzed in terms of rate of RP and individual likelihood of RP. Results A total of 2196 VSs and 201 RPs were performed across all treatment sites. H&N and lung or chest disease sites represented the largest proportion of plan modifications in terms of rate of re-plan (RoR: 54% and 58%, respectively) and individual likelihood of RP on a per patient basis (likelihood of RP [RP%]: 46% and 39%, respectively). These sites required RP beyond 4 weeks of treatment, suggesting continued benefit for frequent, periodic VS. Disease sites in the lower pelvis demonstrated a low yield for RP per VS (0.01-0.02), suggesting that decreasing VS frequency, particularly late in treatment, may be reasonable. Conclusions A large degree of variation in RoR and individual RP% was observed between anatomic treatment sites. The present retrospective analysis provides data to help develop anatomic site–based VS protocols.