Browsing by Author "Balter, James M."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Modeling Patient-Specific Dose-Function Response for Enhanced Characterization of Personalized Functional Damage
    (Elsevier, 2018-11-15) Rocky Owen, Daniel; Boonstra, Phillip S.; Viglianti, Benjamin L.; Balter, James M.; Schipper, Matthew J.; Jackson, William C.; El Naqa, Issam; Jolly, Shruti; Ten Haken, Randall K.; Spring Kong, Feng-Ming; Matuszak, Martha M.; Radiation Oncology, School of Medicine
    PURPOSE: Functional-guided radiation therapy (RT) plans have the potential to limit damage to normal tissue and reduce toxicity. Although functional imaging modalities have continued to improve, a limited understanding of the functional response to radiation and its application to personalized therapy has hindered clinical implementation. The purpose of this study was to retrospectively model the longitudinal, patient-specific dose-function response in non-small cell lung cancer patients treated with RT to better characterize the expected functional damage in future, unknown patients. METHODS AND MATERIALS: Perfusion single-photon emission computed tomography/computed tomography scans were obtained at baseline (n = 81), midtreatment (n = 74), 3 months post-treatment (n = 51), and 1 year post-treatment (n = 26) and retrospectively analyzed. Patients were treated with conventionally fractionated RT or stereotactic body RT. Normalized perfusion single-photon emission computed tomography voxel intensity was used as a surrogate for local lung function. A patient-specific logistic model was applied to each individual patient's dose-function response to characterize functional reduction at each imaging time point. Patient-specific model parameters were averaged to create a population-level logistic dose-response model. RESULTS: A significant longitudinal decrease in lung function was observed after RT by analyzing the voxelwise change in normalized perfusion intensity. Generated dose-function response models represent the expected voxelwise reduction in function, and the associated uncertainty, for an unknown patient receiving conventionally fractionated RT or stereotactic body RT. Differential treatment responses based on the functional status of the voxel at baseline suggest that initially higher functioning voxels are damaged at a higher rate than lower functioning voxels. CONCLUSIONS: This study modeled the patient-specific dose-function response in patients with non-small cell lung cancer during and after radiation treatment. The generated population-level dose-function response models were derived from individual patient assessment and have the potential to inform functional-guided treatment plans regarding the expected functional lung damage. This type of patient-specific modeling approach can be applied broadly to other functional response analyses to better capture intrapatient dependencies and characterize personalized functional damage.
  • Thumbnail Image
    Item
    Stereotactic Transcranial Focused Ultrasound Targeting System for Murine Brain Models
    (IEEE, 2021) Choi, Sang W.; Gerhardson, Tyler I.; Duclos, Sarah E.; Surowiec, Rachel; Scheven, Ulrich; Galban, Stefanie; Lee, Fred T., Jr.; Greve, Joan M.; Balter, James M.; Hall, Timothy L.; Xu, Zhen; Radiology and Imaging Sciences, School of Medicine
    An inexpensive, accurate focused ultrasound stereotactic targeting method guided by pre-treatment MRI images for murine brain models is presented. Uncertainty of each sub-component of the stereotactic system was analyzed. The entire system was calibrated using clot phantoms. The targeting accuracy of the system was demonstrated with an in vivo mouse glioblastoma (GBM) model. The accuracy was quantified by the absolute distance difference between the prescribed and ablated points visible on the pre- and post-treatment MR images, respectively. A pre-calibration phantom study (N= 6) resulted in an error of 0.32 ± 0.31, 0.72 ± 0.16, and 1.06 ± 0.38 mm in axial, lateral, and elevational axes, respectively. A post-calibration phantom study (N= 8) demonstrated a residual error of 0.09 ± 0.01, 0.15 ± 0.09, and 0.47 ± 0.18 mm in axial, lateral, and elevational axes, respectively. The calibrated system showed significantly reduced (p<0.05) error of 0.20 ± 0.21, 0.34 ± 0.24, and 0.28 ± 0.21 mm in axial, lateral and elevational axes, respectively in the in vivo GBM tumor-bearing mice (N= 10).