Purpose: Chemo‐radiation therapy (CRT) is widely used in treating patients with locally advanced non‐small cell lung cancer (NSCLC). Determination of the likelihood of patient response to treatment and optimization of treatment regime is of clinical significance. Up to date, no imaging biomarker has reliably correlated to NSCLC patient survival rate. This pilot study is to extract CT texture information from tumor regions for patient survival prediction. Methods: Thirteen patients with stage II‐III NSCLC were treated using CRT with a median dose of 6210 cGy. Non‐contrast‐enhanced CT images were acquired for treatment planning and retrospectively collected for this study. Texture analysis was applied in segmented tumor regions using the Local Binary Pattern method (LBP). By comparing its HU with neighboring voxels, the LBPs of a voxel were measured in multiple scales with different group radiuses and numbers of neighbors. The LBP histograms formed a multi‐dimensional texture vector for each patient, which was then used to establish and test a Support Vector Machine (SVM) model to predict patients’ one year survival. The leave‐one‐out cross validation strategy was used recursively to enlarge the training set and derive a reliable predictor. The predictions were compared with the true clinical outcomes. Results: A 10‐dimensional LBP histogram was extracted from 3D segmented tumor region for each of the 13 patients. Using the SVM model with the leave‐one‐out strategy, only 1 out of 13 patients was misclassified. The experiments showed an accuracy of 93%, sensitivity of 100%, and specificity of 86%. Conclusion: Within the framework of a Support Vector Machine based model, the Local Binary Pattern method is able to extract a quantitative imaging biomarker in the prediction of NSCLC patient survival. More patients are to be included in the study.

Purpose: To quantitatively compare and evaluate the dosimetry difference between breast brachytherapy protocols with different fractionation using deformable image registration. Methods: The accumulative dose distribution for multiple breast brachytherapy patients using four different applicators: Contura, Mammosite, Savi, and interstitial catheters, under two treatment protocols: 340cGy by 10 fractions in 5 days and 825cGy by 3 fractions in 2days has been reconstructed using a two stage deformable image registration approach. For all patients, daily CT was acquired with the same slice thickness (2.5mm). In the first stage, the daily CT images were rigidly registered to the initial planning CT using the registration module in Eclipse (Varian) to align the applicators. In the second stage, the tissues surrounding the applicator in the rigidly registered daily CT image were non‐rigidly registered to the initial CT using a combination of image force and the local constraint that enforce zero normal motion on the surface of the applicator, using a software developed in house. We calculated the dose distribution in the daily CTs and deformed them using the final registration to convert into the image domain of the initial planning CT. The accumulative dose distributions were evaluated by dosimetry parameters including D90, V150 and V200, as well as DVH. Results: Dose reconstruction results showed that the two day treatment has a significant dosimetry improvement over the five day protocols. An average daily drop of D90 at 1.3% of the prescription dose has been observed on multiple brachytherapy patients. There is no significant difference on V150 and V200 between those two protocols. Conclusion: Brachytherapy with higher fractional dose and less fractions has an improved performance on being conformal to the dose distribution in the initial plan. Elongated brachytherapy treatments need to consider the dose uncertainty caused by the temporal changes of the soft tissue.

Purpose: To develop an automated algorithm for aperture quality assurance for double scattering proton radiotherapy. Methods: Anterior‐Posterior scout images were acquired on a CT scanner for five brass apertures (2 large, 3 small) with 120 kVp and 10mA. A semi‐automated algorithm was developed for the QA process. The input includes a user selecting the scout image and the associated patient plan, field and aperture size. The program automatically thresholds the scout image. Next, a connectivity algorithm is used to determine the points associated with the central shape to obtain the contour. To compare with the plan contour, the program converts the detected and plan contours into polar coordinates, interpolates the data to a 1 degree spaced grid, and determines the differences in radial distance at each grid point. Results: The mean and maximum difference and the percentage of points with distance differences less than 1.25 mm (due to the divergent cut of the aperture) between the detected and plan field aperture contours were obtained. A repeatability coefficient was derived based on repeated scanning and processing of three of the apertures. The mean difference for five apertures was 0.44 +/−0.08 mm. The maximum difference in distance was 1.2 +/−0.23 mm for all apertures. The Repeatability Coefficient was +/−0.038 mm, indicating the technique is highly repeatable. The mean percent of points with distance less than 1.25 mm was 97.41 +/−0.35%. Conclusion: Automated CT scout image based proton aperture QA is feasible, saves time, and provides a quantitative metric for proton patient specific aperture QA.

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Purpose:The broad‐slow‐rising entrance dose region proximal to the Bragg peak made by a mono‐energetic proton beam could potentially be used for total body irradiation (TBI). Due to the quasi‐uniform dose deposition, customized thickness compensation may not be required to deliver a uniform dose to patients with varied thickness. We investigated the possibility, efficacy, and hardware requirement to use such proton beam for TBI.Methods:A wedge shaped water phantom with thickness varying from 2 cm to 40 cm was designed to mimic a patient. Geant4 based Monte Carlo code was used to simulate broad mono‐energetic proton beams with energy ranging from 250 MeV to 300 MeV radiating the phantom. A 6 MV photon with 1 cm water equivalent build‐up used for conventional TBI was also calculated. A paired‐opposing beam arrangement with no thickness compensation was used to generate TBI plans for all beam energies. Dose from all particles were scored on a grid size of 2 mm3. Dose uniformity across the phantom was calculated to evaluate the plan. The field size limit and the dose uniformity of Mevion S250 proton system was examined by using radiochromic films placed at extended treatment distance with the open large applicator and 90° gantry angle.Results:To achieve a maximum ± 7.5% dose variation, the largest patient thickness variation allowed for 250 MeV, 275 MeV, and 300 MeV proton beams were 27.0 cm, 34.9 cm and 36.7 cm. The value for 6 MV photon beam was only 8.0 cm to achieve the same dose variation. With open gantry, Mevion S250 system allows 5 m source‐to‐surface distance producing an expected 70 cm2 field size.Conclusion:Energetic proton beam can potentially be used to deliver TBI. Treatment planning and delivery would be much simple since no thickness compensation is required to achieve a uniform dose distribution.