Current Projects

Clinical dosimetry. WB planar, SPECT/CT, or PET/CT images are acquired at different time points following diagnostic administration of radioactivity or radiolabeled substances of patients. The images are used to estimate absorbed dose to tumor and normal organs. Most analyses use 3D-RD, an in-house software package under continuous development, which incorporates radiobiologic modeling. Projects include:

Modeling. Clinical dosimetry is often limited by the resolution of the imaging modalities. In order to to calculate absorbed dose to organs (or tumors) whose scale is below that of the imaging resolution, dosimetry is supplemented with geometrical models and personalized using anatomical and physiological information from patient data. These include:

Alpha dosimetry. Alpha particles present a particular challenge. The range of these particles decaying from therapeutic radioisotopes is on the order of 80 microns, well below the imaging threshold and on a scale much smaller than the typical normal organ. Dr. Hobbs is developing an alpha-particle dosimetry model based on function sub-unit anatomical modeling and which uses a macro-to-micro approach to relate macroscopically measured activity to apportion the activity and dose to the sub-unit compartments. Elements of this project include:

Lab Work. Dr. Hobbs is actively involved in the lab, where he performs tail vein injections and bio-distribution and provides assistance to Dr. Song. He is working on bone marrow dosimetry and specifically how tumor burden and prior chemotherapy affects the dosimetry. Bone marrow toxicity is often the limiting factor in radioimmunotherapy and toxicity studies have previously only concerned themselves with healthy or primary tumor murine models. This research includes a wide range of techniques from microSPECT and WB imaging to bio-distribution and histopathology using a variety of radioactive sources such as alpha and beta emitting radioisotopes and external beam radiation.

External Beam. In addition to his work in the RTD lab, Dr. Hobbs is active in the department of Radiation Oncology, where he is currently following a medical physics residency. His projects in this field include: