@conference{1e8542b40cf04a8a8c88eef648123b45,
title = "Image-guided 166Ho microbrachytherapy: Quantification of radioactive holmium microspheres after intratumoral injection and development of a dosimetry method using computed tomography",
abstract = "Title • Image-guided 166Ho microbrachytherapy: Quantification of radioactive holmium microspheres after intratumoral injection and development of a dosimetry method using computed tomography.Introduction • Microbrachytherapy by intratumoral injection of radioactive 166Ho microspheres (166HoMS) has promising results and minimal morbidity in companion animals with inoperable tumors. Results in cats with oral squamous cell carcinoma1 (OSCC) initiated translation of this approach to humans with OSCC, including experimental treatment of humans with end-stage OSCC disease.2 Recently, an interdisciplinary translational project started for development of an image-guided 166Ho-microbrachytherapy for brain malignancies.3 A challenge in 166Ho-microbrachytherapy is achieving sufficient intratumoral dose distribution. Ideally, real-time dose monitoring would enable adjustments during the treatment procedure. Therefore, a CT-based dosimetry model was developed in a rabbit Vx-2 tumor model.Materials and methods • 166Ho calibration curves were created for CT and µCT. Technique of quantification of intratumoral 166HoMS was investigated by manually determining HU-threshold levels to filter out background tissue and performing adjustments of extracted 166HoMS images for mean tissue HU values. Subsequently, standardized background HU-threshold levels were applied for CT quantification of intratumoral 166HoMS in 5 Vx-2 tumors. 3D dose mapping was performed using an existing 166Ho dose kernel for SPECT adjusted to (µ)CT dimensions. Proof of principle was tested in a feline OSCC after treatment with 166Ho-microbrachytherapy.Results • On average 76% of the injected 166HoMS was detected by CT using a fixed background HU-threshold level. A 3D dose map was constructed for the feline OSCC (Figure 1). Considering the high tumor-absorbed doses with minimal side effects in 166Ho-microbrachytherapy, underestimation of 166HoMS content will not necessarily affect treatment outcome.Conclusions • CT enables fast and high-resolution quantitative imaging of 166HoMS distribution. ",
author = "{van Nimwegen}, S.A.",
year = "2018",
month = apr,
day = "9",
language = "English",
note = "Veterinary Society of Surgical Oncology symposium 2018 : MassIVe in Maui, VSSO ; Conference date: 09-04-2018 Through 11-04-2018",
url = "https://www.vsso.org/index.php/2-uncategorised/493-vsso-2018-symposium",
}