Development of a SPECT-based 3-D methodology for internal dosimetry of radioimmunotherapy

Journal Article · Sun May 01 04:00:00 EDT 1994 · Journal of Nuclear Medicine

OSTI ID:197990

Giap, H B; Podoloff, D A; Boyer, A L ^[1]

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1. Univ. of Texas M.D. Anderson Cancer Center, Houston, TX (United States); and others

Accurate estimate of absorbed dose to target tumors and normal tissues in the body is an important requirement for establishing fundamental dose-response relationships for radioimmunotherapy. Two major obstacles have been the difficulty in obtaining an accurate patient-specific 3-D activity map in-vivo and calculating the resulting absorbed dose. The conventional methodology employs gamma camera planar imaging to obtain average organ activities and S-factors from the MIRD formalism to provide one average absorbed dose to each organ of interest in patients. Significant errors in these absorbed dose estimates arise from the assumptions of standard man model and lack of S-factors for tumor volumes. This study investigated a methodology for 3-D internal dosimetry (with Iodine-131), which integrates the 3-D biodistribution of the radionuclide acquired from SPECT with a dose point kernel convolution technique to provide the 3-D distribution of absorbed dose. Accurate SPECT images were reconstructed with appropriate methods for noise filtering, attenuation correction, and Compton scatter correction. The SPECT images were converted into activity maps using an I-131-filled calibration phantom. The activity map was convolved with I-131 dose point kernel using a 3-D fast Fourier transform to yield a 3-D distribution of absorbed dose. The 3-D absorbed dose map was then processed to provide the absorbed dose distribution of the regions of interest. The activity quantitation by SPECT compared to activities in an Alderson abdominal phantom (with spleen, liver and tumor) with errors of -16.3% to 4.4%. Volume quantitation errors ranged from -4.0 to 5.9%. Good agreement (percent differences were less than 8%) was found between the absorbed dose due to penetrating radiation calculated from this methodology and TLD measurement in a cylindrical phantom filled with I-131.

• OSTI ID: 197990
• Report Number(s): CONF-940605--
• Journal Information: Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 35; ISSN 0161-5505; ISSN JNMEAQ
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
CALIBRATION
DOSE-RESPONSE RELATIONSHIPS
DOSIMETRY
ERRORS
IMAGES
IODINE 131
PATIENTS
RADIOIMMUNOTHERAPY
SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
TISSUES
TOXICITY