Feasibility of automated 3-dimensional magnetic resonance imaging pancreas segmentation.

PurposeWith the advent of MR guided radiotherapy, internal organ motion can be imaged simultaneously during treatment. In this study, we evaluate the feasibility of pancreas MRI segmentation using state-of-the-art segmentation methods.Methods and materialT2 weighted HASTE and T1 weighted VIBE images were acquired on 3 patients and 2 healthy volunteers for a total of 12 imaging volumes. A novel dictionary learning (DL) method was used to segment the pancreas and compared to t mean-shift merging (MSM), distance regularized level set (DRLS), graph cuts (GC) and the segmentation results were compared to manual contours using Dice's index (DI), Hausdorff distance and shift of the-center-of-the-organ (SHIFT).ResultsAll VIBE images were successfully segmented by at least one of the auto-segmentation method with DI >0.83 and SHIFT ≤2 mm using the best automated segmentation method. The automated segmentation error of HASTE images was significantly greater. DL is statistically superior to the other methods in Dice's overlapping index. For the Hausdorff distance and SHIFT measurement, DRLS and DL performed slightly superior to the GC method, and substantially superior to MSM. DL required least human supervision and was faster to compute.ConclusionOur study demonstrated potential feasibility of automated segmentation of the pancreas on MRI images with minimal human supervision at the beginning of imaging acquisition. The achieved accuracy is promising for organ localization

A Model-Based Approach to Predict Short-Term Toxicity Benefits With Proton Therapy for Oropharyngeal Cancer

Purpose: The aim of this study was to generate normal tissue complication probability (NTCP) models in patients treated with either proton beam therapy (PBT) or intensitymodulated radiation therapy (IMRT) for oropharynx cancer and to use a model-based approach to investigate the added value of PBT in preventing treatment complications. Methods and Materials: For patients with advanced-stage oropharynx cancer treated with curative intent (PBT, n = 30; IMRT, n = 175), NTCP models were developed using multivariable logistic regression analysis with backward selection. For PBTtreated patients, an equivalent IMRT plan was generated to serve as a reference to determine the benefit of PBT in terms of NTCP. The models were then applied to the PBT-treated patients to compare predicted and observed clinical outcomes (calibration- in-the-large). Five binary endpoints were analyzed at 6 months after treatment: dysphagia >= grade 2, dysphagia >= grade 3, xerostomia >= grade 2, salivary duct inflammation >= grade 2, and feeding tube dependence. Corresponding toxicity grading was based on National Cancer Institute Common Terminology Criteria for Adverse Events version 4. Paired t tests and Wilcoxon rank tests were used to compare mean NTCP results for endpoints between PBT and IMRT. Results: NTCP models developed based on outcomes from all patients were applied to those receiving PBT. NTCP values were calculated for the equivalent IMRT plans for all PBT-treated patients, revealing significantly higher NTCP values with IMRT. PBT was associated with statistically significant reductions in the mean NTCP values for each endpoint at 6 months after treatment, with the largest absolute differences in rates of >= grade 2 dysphagia and >= grade 2 xerostomia. Conclusions: NTCP models predict significant improvements in the probability of short-term, treatment-related toxicity with PBT compared with IMRT for oropharyngeal cancer. This study demonstrates an NTCP model-based approach to compare predicted patient outcomes when randomized data are not available. (C) 2019 Elsevier Inc. All rights reserved

Feasibility of automated 3-dimensional magnetic resonance imaging pancreas segmentation.

PurposeWith the advent of MR guided radiotherapy, internal organ motion can be imaged simultaneously during treatment. In this study, we evaluate the feasibility of pancreas MRI segmentation using state-of-the-art segmentation methods.Methods and materialT2 weighted HASTE and T1 weighted VIBE images were acquired on 3 patients and 2 healthy volunteers for a total of 12 imaging volumes. A novel dictionary learning (DL) method was used to segment the pancreas and compared to t mean-shift merging (MSM), distance regularized level set (DRLS), graph cuts (GC) and the segmentation results were compared to manual contours using Dice's index (DI), Hausdorff distance and shift of the-center-of-the-organ (SHIFT).ResultsAll VIBE images were successfully segmented by at least one of the auto-segmentation method with DI >0.83 and SHIFT ≤2 mm using the best automated segmentation method. The automated segmentation error of HASTE images was significantly greater. DL is statistically superior to the other methods in Dice's overlapping index. For the Hausdorff distance and SHIFT measurement, DRLS and DL performed slightly superior to the GC method, and substantially superior to MSM. DL required least human supervision and was faster to compute.ConclusionOur study demonstrated potential feasibility of automated segmentation of the pancreas on MRI images with minimal human supervision at the beginning of imaging acquisition. The achieved accuracy is promising for organ localization

Predictors of distant metastasis after combined HDR brachytherapy and external beam radiation for prostate cancer.

PurposeTo determine predictors of distant metastases (DM) in prostate cancer patients treated with high dose rate brachytherapy boost (HDR-B) and external beam radiation therapy (EBRT).Material and methodsFrom 1991 to 2002, 768 men with localized prostate cancer were treated with HDR-B and EBRT. The mean EBRT dose was 37.5 Gy (range: 30.6-45 Gy), and the HDR-B was 22 or 24 Gy delivered in 4 fractions. Univariate and multivariate analyses using a Cox proportional hazards model including age at diagnosis, T stage, Gleason score (GS), pretreatment PSA, biologically equivalent dose (BED), and use of androgen deprivation therapy (ADT) was used to determine predictors of developing distant metastases.ResultsThe median follow-up time for the entire patient population was 4.2 years (range: 1-11.2 years). Distant metastases were identified in 22/768 (3%) of patients at a median of 4.1 years. PSA failure according to the Phoenix definition developed in 3%, 5%, and 14% of men with low, intermediate, and high risk disease with a median time to failure of 3.8 years. Prostate cancer specific mortality was observed in 2% of cases. T stage, GS, and use of ADT were significantly associated with developing DM on univariate analysis. GS, and use of ADT were the only factors significantly associated with developing DM on multivariate analysis (p < 0.01). Patients who received ADT had significantly higher risk features suggesting patient selection bias for higher DM in this group of patients rather than a negative interaction between HDR-B and EBRT.ConclusionsIn men treated with HDR-B and EBRT, GS is a significant factor on multivariate analysis for developing distant metastasis

Feasibility of automated 3-dimensional magnetic resonance imaging pancreas segmentation

Purpose: With the advent of magnetic resonance imaging (MRI) guided radiation therapy, internal organ motion can be imaged simultaneously during treatment. In this study, we evaluate the feasibility of pancreas MRI segmentation using state-of-the-art segmentation methods. Methods and materials: T2-weighted half-Fourier acquisition single-shot turbo spin-echo and T1 weighted volumetric interpolated breath-hold examination images were acquired on 3 patients and 2 healthy volunteers for a total of 12 imaging volumes. A novel dictionary learning (DL) method was used to segment the pancreas and compared to t mean-shift merging, distance regularized level set, and graph cuts, and the segmentation results were compared with manual contours using Dice's index, Hausdorff distance, and shift of the center of the organ (SHIFT). Results: All volumetric interpolated breath-hold examination images were successfully segmented by at least 1 of the autosegmentation method with Dice's index >0.83 and SHIFT ≤2 mm using the best automated segmentation method. The automated segmentation error of half-Fourier acquisition single-shot turbo spin-echo images was significantly greater. DL is statistically superior to the other methods in Dice’s overlapping index. For the Hausdorff distance and SHIFT measurement, distance regularized level set and DL performed slightly superior to the graph cuts method, and substantially superior to mean-shift merging. DL required least human supervision and was faster to compute. Conclusions: Our study demonstrated potential feasibility of automated segmentation of the pancreas on MRI scans with minimal human supervision at the beginning of imaging acquisition. The achieved accuracy is promising for organ localization

Stereotactic body radiotherapy for the treatment of presacral recurrences from rectal cancers

Purpose: Management of recurrent presacral rectal cancer is often not amenable to curative surgery. The goal of this study is to evaluate the safety and efficacy of cyberknife stereotactic body radiotherapy (SBRT) in the management of presacral recurrences. Materials and Methods: Between April 2003 and October 2008, 14 patients with presacral tumors from rectal adenocarcinoma were SBRT treated. Eleven patients were treated with 36 Gy in 3 fractions and 3 patients were treated with single fraction of 12, 16 or 18 Gy. Tumor response was assessed using response evaluation and criteria in solid tumor (RECIST) criteria. Toxicities were assessed with common terminology criteria adverse events v 3.0. Pain control was assessed. Results: One patient (6.7%) received SBRT as boost therapy. All patients had prior radiotherapy [median 50.4 Gy (20 - 81 Gy)]. Median tumor volume was 52.5 cc (19 - 110 cc). At initial follow-up of a median 4.9 months (1 - 16.3 months), treatment responses were complete response (n=3) and stable disease (n=8). With a median follow-up of 16.5 months (6 - 69 months), the one- and two-year LC rates were 90.9 and 68.2%, respectively, and the one- and two-year OS rates were 90 and 78.8%, respectively. No factors were significantly predictive of LC and OS. There were no grade 3 or 4 toxicities. Fifty percent (n=7) of our patients experienced pain with recurrence before treatment and 4 (57.1%) of them reported no pain after completion of their SBRT. Conclusions: Stereotactic body radiotherapy for presacral recurrence of rectal adenocarcinoma is an efficacious and well-tolerated treatment modality which allows for palliation of pain

Re-Irradiation Therapy for Locally Recurrent Head and Neck Cancer: A National Survey of Practice Patterns

<p>Using a customized survey consisting of two de-identified clinical scenarios with a total of 86 questions, we showed that substantial variability exists regarding recommendations for therapy of recurrent head and neck cancer. For inoperable gross recurrence arising in a previously irradiated field, recommendations were re-irradiation with curative intent (73%), re-irradiation with palliative intent (4%), chemotherapy alone (5%), and referral to tertiary center (18%). After salvage surgery, only 33% recommended adjuvant re-irradiation, with the remainder preferring observation (46%), chemotherapy alone (10%), and referral to tertiary center (11%). Significant differences were observed with respect to dose, fractionation, technique, and systemic therapy recommendations.</p