An Liu, PhD
Radiation Oncology Department
City of Hope Medical Center
Duarte, CA 91010
Radioimmunotherapy (RIT) utilizes monoclonal antibodies (MABs) as a carrier to send radionuclides to tumor sites. The concept and current clinical status of various RIT agents are discussed. In order to calculate the absolute radiation dose received by tumor and other critical organs, an integrated PC-based radionuclide imaging and therapy treatment planning and dosimetry system (RTDS) was developed. The overall design of RTDS is based on an object-oriented model. It includes two major components: a database subsystem and a calculation module subsystem. The database developed under Microsoft Access stores and organizes the clinical data. Calculation modules developed with Microsoft Visual Basic are the calculation processes needed to estimate the final absorbed radiation doses. These consist of 4 subsystems: imaging-processing module, quantitative activity calculation module, modeling module and dose calculation module. The imaging-processing module handles image display and processing. The quantitative activity calculation module estimates the radioactivities in organs. Here, the user is provided with three options of algorithm: the generally used conjugate view method, our CT assisted matrix inversion (CAMI) method and quantitative SPECT. The modeling module handles the modeling of biological data. Both simple curve fitting routines and compartment model are incorporated into the system. The dose calculation module estimates absorbed radiation doses. Two dosimetry models are developed: the generally used MIRDOSE3 algorithm and our Monte Carlo assisted voxel source kernel (MAVSK) algorithm which uses the patient CT volume to perform real-time (calculation under 1 minute) patient-specific dosimetry analysis and generate dose volume histograms (DVH). All final and intermediate dosimetry results are saved to and tracked by the database. RTDS will greatly improve the quality of dosimetry analyses for radionuclide imaging and therapy, especially for radioimmunotherapy. It provides a user-friendly software program and standard format for internal emitter absorbed dose estimation.