@article{magestro_cahoon_gieger_nolan_2019, title={Radiotherapy isocenters verified by matching to bony landmarks of the canine and feline head differ when localized using volumetric versus planar imaging}, volume={17}, ISSN={["1476-5829"]}, DOI={10.1111/vco.12522}, abstractNote={Abstract The “gold standard” for verification of patient positioning before linear accelerator‐based stereotactic radiation therapy is kilovoltage cone‐beam computed tomography (kV‐CBCT), which is not uniformly available or utilized; planar imaging is sometimes used instead. The primary aim of this study was to determine if the position of the bony skull, when used as a surrogate for isocenter verification, is different when orthogonal megavoltage (MV) portal or kilovoltage (kV/kV) radiographs are used for image guidance, rather than kV‐CBCT. A secondary aim was to determine the influence of intra‐observer variability, body size and skull conformation on positioning, as determined using these three imaging modalities. Dogs and cats receiving radiotherapy of the head were recruited for this prospective analytical study. Planar (MV portal and kV/kV images) and volumetric (kV‐CBCT) images were acquired before treatment, and manually coregistered with reference images. Differences in skull position when matched based on MV portal, kV/kV images and kV‐CBCT were compared. A total of 65 subjects and 148 unique datasets were evaluated. The Wilcoxon rank‐sum test was used to evaluate effects of transitioning between imaging modalities. When comparing magnitude of shifts in MV to kV‐CBCT, MV to kV/kV and kV/kV to kV‐CBCT, there were statistically significant differences. Results were not measurably impacted by body size, skull conformation or interobserver differences. Based on shift magnitude and direction, an isotropic setup margin of at least 1 mm should be incorporated within the planning target volume when MV or kV planar imaging is used for position verification.}, number={4}, journal={VETERINARY AND COMPARATIVE ONCOLOGY}, author={Magestro, Leanne M. and Cahoon, Joyce Y. and Gieger, Tracy L. and Nolan, Michael W.}, year={2019}, month={Dec}, pages={562–569} }
 @article{magestro_gieger_nolan_2018, title={Stereotactic body radiation therapy for heart-base tumors in six dogs}, volume={20}, ISSN={["1875-0834"]}, DOI={10.1016/j.jvc.2018.04.001}, abstractNote={Heart-base tumors are increasingly treated with radiotherapy, yet safety and efficacy are incompletely understood. This case series describes outcomes after stereotactic body radiation therapy (SBRT) for presumed chemodectoma. Six pet dogs. A retrospective study was performed, including dogs with a clinical diagnosis of chemodectoma and treatment with three-fraction SBRT (30 Gy total). Heart-base tumors, presumed or confirmed to be chemodectomas, were diagnosed via histopathology or imaging. Treatment was delivered with intensity modulation and cone-beam computed tomography–based image guidance, using a linear accelerator and robotic couchtop. Intrafraction respiratory motion was managed with either neuromuscular blockade and breath-holding (n = 3) or high-frequency jet ventilation (n = 3); mean total anesthesia times for each technique were 165 and 91 min per fraction, respectively. Four tumors were assessed after SBRT; tumor volume decreased by 30–76%. Possible treatment-related complications included cough, tachyarrhythmias, and congestive heart failure. Two dogs experienced sudden death 150 and 294 days after SBRT. Three dogs are alive 408–751 days after SBRT, and one dog died of unrelated disease 1,228 days after SBRT. This SBRT protocol resulted in rapid tumor volume reduction, and jet ventilation effectively reduced treatment delivery times. However, cardiac arrhythmias (presumably tumor or treatment associated) and sudden death were common after SBRT. Therefore, SBRT is a potentially useful treatment but may not be appropriate for dogs with incidentally diagnosed, slowly growing tumors, which are not causing cardiovascular disturbances. Longer follow-up and larger case numbers are needed to more completely define safety and impact of treatment on long-term survivability.}, number={3}, journal={JOURNAL OF VETERINARY CARDIOLOGY}, author={Magestro, L. M. and Gieger, T. L. and Nolan, M. W.}, year={2018}, month={Jun}, pages={186–197} }