Ross Zeitlin

Dosimetric predictors of local control and complications in gynecologic transperineal implant patients: The medical college of wisconsin experience

Investigate the relationship between dosimetric parameters with local control (LC) and complications following transperineal high-dose rate (HDR) interstitial brachytherapy (ISBT) for gynecologic (GYN) malignancies. Between 2001 and 2016, 59 patients were treated for primary or recurrent GYN malignancies. Most patients received external beam irradiation, followed by transperineal ISBT via the Syed-Neblett applicator set with CT-based planning. Treatment plans were retrospectively reviewed to evaluate for an association among LC or toxicity with the equivalent dose at 2 Gy per fraction (EQD2) for the clinical target volume (CTV), 0.1 cc (D0.1cc), and 2 cc (D2cc) volumes of the organs at risk (OAR), low/high dose volumes for the OAR and CTV, and ratio of dose at the core vs. the implant periphery. The median follow-up among survivors was 24 months. 34% of patients had a component of local failure and in 12%, this was isolated. Late grade 3 (G3) toxicity occurred in 15% of patients. There were no G4-5 toxicities. Rectal D0.1cc > 75 Gy trended toward significance in predicting the development of non-fistula late G2-3 rectal complications. Bladder D0.1cc > 94 Gy significantly predicted for the development of late G2-3 vesicovaginal fistula formation. The ratio of the total dose at the vaginal surface to the needle periphery above 121% trended in predicting for any complication or fistula formation. HDR ISBT combined with EBRT achieved LC in 66% of patients with advanced or recurrent GYN cancers. Rectal and bladder D0.1cc doses may be predictive of complications as may the ratio of the implant dose at the core vs. periphery.

A general framework to develop a radiomic fingerprint for progression-free survival in cervical cancer

Treatment of locally advanced cervical cancer patients includes chemoradiation followed by brachytherapy. Our aim is to develop a delta radiomics (DRF) model from MRI-based brachytherapy treatment and assess its association with progression free survival (PFS). A retrospective analysis of FIGO stage IB- IV cervical cancer patients between 2012 and 2018 who were treated with definitive chemoradiation followed by MRI-based intracavitary brachytherapy was performed. Clinical factors together with 18 radiomic features extracted from different radiomics matrices were analyzed. The delta radiomic features (DRFs) were extracted from MRI on the first and last brachytherapy fractions. Support Vector Machine (SVM) models were fitted to combinations of 2-3 DRFs found significant after Spearman correlation and Wilcoxon rank sum test statistics. Additional models were tested that included clinical factors together with DRFs. A total of 39 patients were included in the analysis with a median patient age of 52 years. Progression occurred in 20% of patients (8/39). The significant DRFs using two DRF feature combinations was a model using auto correlation (AC) and sum variance (SV). The best performing three feature model combined mean, AC & SV. Additionally, the inclusion of FIGO stages with the 2- and 3 DRF combination model(s) improved performance compared to models with only DRFs. However, all the clinical factor + DRF models were not significantly different from one another (all AUCs were 0.77). Our study shows promising evidence that radiomics metrics are associated with progression free survival in cervical cancer.