A Retrospective Cohort Study of Longitudinal Audiologic Assessment in Single and Fractionated Stereotactic Radiosurgery for Vestibular Schwannoma.

BACKGROUND: Fractionated stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) has been theorized to allow for tumor control with higher rates of hearing preservation in selected patients with useful hearing. However, there is a paucity of literature with formal audiologic measures of hearing preservation to support the standard use of fractionated SRS in VS. We hypothesized that fractionation would diminish the amount of hearing damage. OBJECTIVE: To evaluate the relationship between audiologic performance and SRS fractionation scheme. METHODS: We performed an IRB-approved retrospective review of patients treated with 1, 3, or 5 fraction SRS for VS at our institution from 1998 to 2016. Pre- and post-SRS audiograms with speech awareness threshold (SAT) in treated and contralateral ears were obtained. Contralateral ear measurements were used for hearing normalization to account for presbycusis. RESULTS: Fifty-six patients with median audiologic follow-up 2.0 yr (mean 2.66 yr, min-max 0.50-9.45 yr) were included. Patients treated with single fractionation had a significantly worsened SAT (dB) compared to patients treated with 5 fractions (P = .008) and compared to all multifraction patients (P = .009) at 12 to 24 mo follow-up. CONCLUSION: This retrospective analysis supports the use of fractionated SRS to preserve hearing in patients with VS. SAT can be used as an objective metric of hearing response to radiosurgery.

A simple technique to improve calculated skin dose accuracy in a commercial treatment planning system.

Radiation dermatitis during radiotherapy is correlated with skin dose and is a common clinical problem for head and neck and thoracic cancer patients. Therefore, accurate prediction of skin dose during treatment planning is clinically important. The objective of this study is to evaluate the accuracy of skin dose calculated by a commercial treatment planning system (TPS). We evaluated the accuracy of skin dose calculations by the anisotropic analytical algorithm (AAA) implemented in Varian Eclipse (V.11) system. Skin dose is calculated as mean dose to a contoured structure of 0.5 cm thickness from the surface. The EGSnrc Monte Carlo (MC) simulations are utilized for the evaluation. The 6, 10 and 15 MV photon beams investigated are from a Varian TrueBeam linear accelerator. The accuracy of the MC dose calculations was validated by phantom measurements with optically stimulated luminescence detectors. The calculation accuracy of patient skin doses is studied by using CT based radiotherapy treatment plans including 3D conformal, static gantry IMRT, and VMAT treatment techniques. Results show the Varian Eclipse system underestimates skin doses by up to 14% of prescription dose for the patients studied when external body contour starts at the patient's skin. The external body contour is used in a treatment planning system to calculate dose distributions. The calculation accuracy of skin dose with Eclipse can be considerably improved to within 4% of target dose by extending the external body contour by 1 to 2 cm from the patient's skin. Dose delivered to deeper target volumes or organs at risk are not affected. Although Eclipse treatment planning system has its limitations in predicting patient skin dose, this study shows the calculation accuracy can be considerably improved to an acceptable level by extending the external body contour without affecting the dose calculation accuracy to the treatment target and internal organs at risk. This is achieved by moving the calculation entry point away from the skin.

Vanderbilt Head and Neck Symptom Survey version 2.0: report of the development and initial testing of a subscale for assessment of oral health.

BACKGROUND: The prevalence, severity, and functional implications of adverse oral health outcomes attributed to head and neck cancer therapy are largely undefined. We report development of an oral health outcome subscale for the Vanderbilt Head and Neck Symptom Survey (VHNSS). METHODS: Oral health outcome questions were formulated through literature review and consultation with an expert panel. Questions were incorporated into the VHNSS resulting in a 50-item survey, scored 0 (none) to 10 (severe). The tool was administered to 70 subjects who completed radiation to assess for feasibility. RESULTS: Patient acceptance was high with a completion time <10 minutes. A full range of scores was noted for 46 of 50 questions. Oral health symptom burden was high early and late posttreatment. CONCLUSIONS: The VHNSS version 2.0 was feasible and could be completed in a timely manner. Validation studies are ongoing. The high prevalence of adverse oral health outcomes warrants further study.

Reliability and validity of the Vanderbilt Head and Neck Symptom Survey: a tool to assess symptom burden in patients treated with chemoradiation.

BACKGROUND: We describe the development and validation of the Vanderbilt Head and Neck Symptom Survey (VHNSS), which was designed to screen for tumor- and treatment-specific symptoms in patients with head and neck cancer undergoing concurrent chemoradiation (CCR). METHODS: Using a 2-step card sort method, we identified high-impact and high-frequency toxicities in patients with head and neck cancer treated with CCR. This resulted in a 28-item questionnaire which scores symptoms on a 0 to 10 scale (none to severe). The tool was validated using data collected from 5 supportive care studies comprising a total sample of 332 patients with head and neck cancer. RESULTS: Responses to the VHNSS items demonstrated a very consistent pattern (Cronbach's alpha = 0.943) with each item contributing substantially to the global index. Five symptom subscales were identified including "Nutrition," "Pain," "Voice," "Swallow," and "Mucous/Dry Mouth." Each of the cluster scores demonstrated good internal consistency. The pattern of associations between the VHNSS and established tools indicated appropriate convergence and divergence. Comparison of global and subscale scores and objective measure were also in the expected direction providing further evidence of validity. CONCLUSIONS: The findings provide support that the VHNSS is a valid and reliable tool to assess head and neck-specific symptom burden and function loss. Further research to evaluate this screening tool as a part of a systems approach to supportive care is warranted.

Impact of inhomogeneity corrections on dose coverage in the treatment of lung cancer using stereotactic body radiation therapy.

The purpose of this study is to assess the real target dose coverage when radiation treatments were delivered to lung cancer patients based on treatment planning according to the RTOG-0236 Protocol. We compare calculated dosimetric results between the more accurate anisotropic analytical algorithm (AAA) and the pencil beam algorithm for stereotactic body radiation therapy treatment planning in lung cancer. Ten patients with non-small cell lung cancer were given 60 Gy in three fractions using 6 and 10 MV beams with 8-10 fields. The patients were chosen in accordance with the lung RTOG-0236 protocol. The dose calculations were performed using the pencil beam algorithm with no heterogeneity corrections (PB-NC) and then recalculated with the pencil beam with modified Batho heterogeneity corrections (PB-MB) and the AAA using an identical beam setup and monitor units. The differences in calculated dose to 95% or 99% of the PTV, between using the PB-NC and the AAA, were within 10% of prescribed dose (60 Gy). However, the minimum dose to 95% and 99% of PTV calculated using the PB-MB were consistently overestimated by up to 40% and 36% of the prescribed dose, respectively, compared to that calculated by the AAA. Using the AAA as reference, the calculated maximum doses were underestimated by up to 27% using the PB-NC and overestimated by 19% using the PB-MB. The calculations of dose to lung from PB-NC generally agree with that of AAA except in the small high-dose region where PB-NC underestimates. The calculated dose distributions near the interface using the AAA agree with those from Monte Carlo calculations as well as measured values. This study indicates that the real minimum PTV dose coverage cannot be guaranteed when the PB-NC is used to calculate the monitor unit settings in dose prescriptions.