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Health Physics Home > Faculty > Dr. H. Michael Gach Home > Research | ||||||||||||||||||||||||||||||||||||||||
Dr. H. Michael GachAdjunct Associate Professor of Health Physics Contact Information:
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Research ProjectsZevalin Clinical TrialThe Nevada Cancer Institute (NVCI) is the only site in the state of Nevada participating in a national trial of Zevalin (Biogen Idec, Cambridge, MA) for low-grade follicular lymphoma. Dr. Nam Dang, M.D., Ph.D., NVCI’s Chief of Hematological Malignancies, is the principal investigator for this unique study. Lymphoma ranks 5th in cancer incidence and mortality in the U.S. Zevalin is a treatment for certain types of B-cell non-Hodgkin’s lymphoma (NHL) that do not respond to other therapies or that have relapsed (i.e., returned after therapy). Zevalin is a therapeutic regimen that uses a radio-labeled monoclonal antibody Ibritumomab Tiuxetan, combined with another antibody named Rituximab. The Zevalin and Rituximab antibodies target, and bind to, the CD20 antigen of the B-cell lymphocytes.
The Zevalin antibody is first labeled with the radioactive isotope Indium 111 (111In), a gamma-emitter, and imaged using Single Photon Emission Computed Tomography (or SPECT) to verify that the antibody properly distributes within the body. In about 1% of the cases the distribution of the drug is altered (e.g., from excessive uptake in the bone marrow or kidney). If the drug biodistribution is satisfactory, treatment is continued using a version of the Zevalin antibody labeled with the radioactive isotope Yttrium 90 (90Y), a beta-emitter. The radioactive Yttrium can supply a lethal dose of radiation directly to the bound B-cells, and indirectly to neighboring B-cells.
SPECT images showing the whole-body distribution of 111In labeled Zevalin antibody 2 days after injection. From left to right: Anterior, posterior, and 2 pairs of inverted intensity summaries with different windowing levels.
Prostascint Molecular ImagingThe Nevada Cancer Institute (NVCI) is currently one of two sites in Las Vegas that performs novel molecular imaging of prostate cancer using Prostascint (Cytogen Corp., Princeton, NJ). The patient is scanned using NVCI’s dual-head gamma camera to simultaneously acquire two sets of whole-body single photon emission computed tomography (SPECT) images. Prostascint is an antibody (capromab pendetide) labeled with radioactive Indium 111 (111In). The Prostascint flows through the blood stream and binds to prostate cells. An additional scan using the patient’s red blood cells (RBCs) labeled with radioactive Technetium 99m (99mTc) is acquired to measure the background signal of the blood and tissue. The radiologist subtracts the 99mTc-RBC background images from the Prostascint images to identify suspicious regions of activity (e.g., prostate cancer metastases) in or near the prostate, surrounding tissues, and lymph nodes.
From left to right: Coronal SPECT images of 111In-labeled Prostascint and 99mTc-labeled red blood cells; whole body Prostascint signal in anterior and posterior projections with different windowing levels.
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