Purpose: This study was to identify problems and investigate camera parameters that would create effective biodistribution images for treatment planning and dosimetry in patients receiving Y‐90 radionuclide therapy. Method and Materials: Y‐90 energy spectra under different interacting conditions were recorded from MCA, uptake probe and gamma camera. Y‐90 (17.6 MBq) was added to an Anthropomorphic Torso Phantom, with or without water in its tank, with following distribution: liver, 70% with water; right lung, 15% with water; left lung, 15% without water. Imaging was performed on a Siemens eCam, dual head camera with HEGP/MEGP collimators at various energy settings. Y‐90 patient imaging was performed with retained activities of 1.52 GBq and 6.7 kBq Y‐90 labeled microspheres and with 3.7 GBq Y‐90 labeled Zevalin. At 30 minutes post Zevalin injection, a whole body scan was performed using a 194 cm bed length (5 cm/min, total 48 min), 256 × 1024 × 16 matrix without zooming. Results: Y‐90 spectra indicated a characteristic X‐ray peak (Pb. K‐alpha) at 75 keV along with characteristic Bremsstrahlung distribution. Phantom tests found an energy window of 75 keV/50% to produce practical images. Significant uptake in the right lung of the phantom versus other structures was identified. Patient's lungs could not be easily visualized. Conclusion: An energy window (75keV/50%) is adequate for characteristic X‐ray and Bremsstrahlung imaging. Y‐90 imaging depends on scatter characteristic of tissue and does not provide direct biodistribution of Yttrium‐90. Further investigations of imaging technique are needed to assess effective Y‐90 patient imaging.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging