T.T. Sio

Reirradiation of Head and Neck Cancers With Proton Therapy: Outcomes and Analyses

PURPOSEnReirradiation of head and neck (H&N) cancer is a clinical challenge. Proton radiation therapy (PRT) offers dosimetric advantages for normal tissue sparing and may benefit previously irradiated patients. Here, we report our initial experience with the use of PRT for H&N reirradiation, with focus on clinical outcomes and toxicity.nnnMETHODS AND MATERIALSnWe retrospectively reviewed the records of patients who received H&N reirradiation with PRT from April 2011 through June 2015. Patients reirradiated with palliative intent or without prior documentation of H&N radiation therapy were excluded. Radiation-related toxicities were recorded according to the Common Terminology Criteria for Adverse Events Version 4.0.nnnRESULTSnThe conditions of 60 patients were evaluated, with a median follow-up time of 13.6xa0months. Fifteen patients (25%) received passive scatter proton therapy (PSPT), and 45 (75%) received intensity modulated proton therapy (IMPT). Thirty-five patients (58%) received upfront surgery, and 44 (73%) received concurrent chemotherapy. The 1-year rates of locoregional failure-free survival, overall survival, progression-free survival, and distant metastasis-free survival were 68.4%, 83.8%, 60.1%, and 74.9%, respectively. Eighteen patients (30%) experienced acute grade 3 (G3) toxicity, and 13 (22%) required a feeding tube at the end of PRT. The 1-year rates of late G3 toxicity and feeding tube independence were 16.7% and 2.0%, respectively. Three patients may have died of reirradiation-related effects (1 acute and 2 late).nnnCONCLUSIONSnProton beam therapy can be a safe and effective curative reirradiation strategy, with acceptable rates of toxicity and durable disease control.

Defining the value framework for prostate brachytherapy using patient-centered outcome metrics and time-driven activity-based costing

PURPOSEnValue, defined as outcomes over costs, has been proposed as a measure to evaluate prostate cancer (PCa) treatments. We analyzed standardized outcomes and time-driven activity-based costing (TDABC) for prostate brachytherapy (PBT) to define a value framework.nnnMETHODS AND MATERIALSnPatients with low-risk PCa treated with low-dose-rate PBT between 1998 and 2009 were included. Outcomes were recorded according to the International Consortium for Health Outcomes Measurement standard set, which includes acute toxicity, patient-reported outcomes, and recurrence and survival outcomes. Patient-level costs to 1xa0year after PBT were collected using TDABC. Process mapping and radar chart analyses were conducted to visualize this value framework.nnnRESULTSnA total of 238 men were eligible for analysis. Median age was 64 (range, 46-81). Median followup was 5xa0years (0.5-12.1). There were no acute Grade 3-5 complications. Expanded Prostate Cancer Index Composite 50 scores were favorable, with no clinically significant changes from baseline to last followup at 48xa0months for urinary incontinence/bother, bowel bother, sexual function, and vitality. Ten-year outcomes were favorable, including biochemical failure-free survival of 84.1%, metastasis-free survival 99.6%, PCa-specific survival 100%, and overall survival 88.6%. TDABC analysis demonstrated low resource utilization for PBT, with 41% and 10% of costs occurring in the operating room and with the MRI scan, respectively. The radar chart allowed direct visualization of outcomes and costs.nnnCONCLUSIONSnWe successfully created a visual framework to define the value of PBT usingxa0the International Consortium for Health Outcomes Measurement standard set and TDABC costs. PBT is associated with excellent outcomes and low costs. Widespread adoption of this methodology will enable value comparisons across providers, institutions, and treatment modalities.

SU-E-T-19: A New End-To-End Test Method for ExacTrac for Radiation and Plan Isocenter Congruence

PURPOSEnTo combine and integrate quality assurance (QA) of target localization and radiation isocenter End to End (E2E) test of BrainLAB ExacTrac system, a new QA approach was devised using anthropomorphic head and neck phantom. This test insures the target localization as well as radiation isocenter congruence which is one step ahead the current ExacTrac QA procedures.nnnMETHODSnThe head and neck phantom typically used for CyberKnife E2E test was irradiated to the sphere target that was visible in CT-sim images. The CT-sim was performed using 1 mm thickness slice with helical scanning technique. The size of the sphere was 3-cm diameter and contoured as a target volume using iPlan V.4.5.2. A conformal arc plan was generated using MLC-based with 7 fields, and five of them were include couch rotations. The prescription dose was 5 Gy and 95% coverage to the target volume. For the irradiation, two Gafchromic films were perpendicularly inserted into the cube that hold sphere inside. The linac used for the irradiation was TrueBeam STx equipped with HD120 MLC. In order to use ExacTrac, infra-red head-array was used to correlate orthogonal X-ray images.nnnRESULTSnUsing orthogonal X-rays of ExacTrac the phantom was positioned. For each field, phantom was check again with X-rays and re-positioned if necessary. After each setup using ExacTrac, the target was irradiated. The films were analyzed to determine the deviation of the radiation isocenter in all three dimensions: superior-inferior, left-right and anterior-posterior. The total combining error was found to be 0.76 mm ± 0.05 mm which was within sub-millimeter accuracy.nnnCONCLUSIONnUntil now, E2E test for ExacTrac was separately implemented to test image localization and radiation isocenter. This new method can be used for periodic QA procedures.

SU‐E‐T‐301: Evaluation of Simultaneously Integrated Boost (SIB) and Sequential IMRT Boost (SqIB) Treatments of Head and Neck Cancer Using Empirical Radiobiological Modeling

PURPOSEnTo evaluate and compare normal tissue complication probabilities (NTCP) in SIB (simultaneous integrated boost) and SqIB (sequential IMRT boost) IMRT methods in head and neck cancer using the radiobiological modeling of HART program (Histogram Analysis in Radiation Therapy; J Appl Clin Med Phys 11(1): 3013, 2010).nnnMETHODSnOf the 40 SIB IMRT cases identified in a 2-year follow up study, 14 SIB (Rx range: 66-70Gy) cases that developed dysphagia(N=11) or xerostomia(N=10) or both types of complications(N=9) were studied. Similarly 10 SqIB cases (Rx=73.5Gy) was studied previously. The TCP and NTCPs were calculated from the dose-volume histogram (DVH) statistics using the Poisson Statistics (PS) and JT Lyman models respectively. Values for the volume parameter (n), slope parameter (m), tumor control dose (TCD=63.8Gy) and tolerance dose (TD50,5 = 46 and 47 Gy for bilateral parotids and esophagus, respectively) were selected from Luxton et al. (Phys. Med. Biol. 53, 23-36, 2008).nnnRESULTSnIn the SIB method (N=14; Students t-test), TCP of tumor was estimated to be 0.78±0.02; while NTCP for parotids and esophagus were 0.16±0.10, and 0.20±0.06 respectively. The corresponding numbers in the SqIB method (N=10) were 0.83±0.02; 0.45±0.14 and 0.17±0.09 respectively.nnnCONCLUSIONnIn a 2-year follow up study with SIB treatments, the estimated values of NTCP of esophagus correlated with the severity of dysphagia. In addition, the hot spots were also reduced and better parotid sparing was found in SIB method than in SqIB method which may partially be related to smaller prescription doses. However JT Lyman model provided better correlation between severity of xerostomia and NTCP of parotids; and PS models for tumor progression free survivability in SqIB treatments. These findings are not in direct comparison due to the differences in tumors and stages. This novel methodology of radiobiological outcome-related analysis can be utilized to evaluate different treatment plan techniques.

SU-E-T-595: A Study of Sequential and Simultaneously Integrated Boost IMRT Methods in Head and Neck Cancer

PURPOSEnThe purpose of this study was to obtain the characteristics of the sequential (SqB) and simultaneous integrated boost (SIB) IMRT methods in head and neck cancer using HART (Histogram Analysis in Radiation Therapy) program.nnnMETHODSnTen SqB and seventeen SIB IMRT cases were studied retrospectively. A cumulative mean dose of 71.3 Gy was prescribed sequentially, and a mean dose of 66.2 Gy for SIB method. Homogeneity (HI), radiation conformality indices (RCI) and quality factor (QF) were calculated from dose-volume histograms (DVHs). In order to estimate the radiobiological outcomes of NTCP, DVH statistics for the critical and hot spots were utilized with Poisson statistics and JT Lyman models in HART.nnnRESULTSnHI, RCI, and QF were 1.11±0.02, 0.97±0.01, 1.00±0.02 in SIB method; and 1.10±0.01, 0.98±0.01, and 0.93±0.03 in SqB method, respectively. Critical spots for parotids, larynx, and esophagus were 0.75±0.03, 0.06±0.02, and 0.34±0.02 in SqB method, and 0.29±0.07, <0.01, and 0.22±0.06 in SIB method, respectively. Hot spots for parotids, larynx, and esophagus were 0.34±0.03, 0.54±0.02, and <0.01, respectively in SqB method whereas 0.10±0.05, <0.01, and 0.05±0.03 in SIB method, respectively. NTCP estimates for parotids, larynx, and esophagus were 0.45±0.14, 0.03±0.01, and 0.17±0.09 in SqB method, and 0.09±0.04, <0.01, and 0.18±0.04 in SIB method, respectively.nnnCONCLUSIONnFor both boost methods mean HIs were comparable while mean RCI was better with SqB than SIB method. QF was significantly better in SIB than in SqB. Critical spots and hot spots were reduced in SIB method. Both SqB and SIB methods yielded similar NTCP for larynx and esophagus. Although better parotid sparing with SIB method than SqB was observed; due to the differences in tumors, stages and doses more patient data and detailed analyses should be followed for comparison. The radiobiological outcome-related analysis using DVHs can be utilized to evaluate different treatment planning techniques.