Quantitative analysis of 90Y Bremsstrahlung SPECT-CT images for application to 3D patient-specific dosimetry

Cancer Biother Radiopharm. 2009 Feb;24(1):145-54. doi: 10.1089/cbr.2008.0543.


Aim: The aim of this study was to evaluate the accuracy of the activity quantification of single-photon emission computed tomography/computed tomography (SPECT-CT) (90)Y-Bremsstrahlung images and to validate the S-voxel method.

Methods: An anthropomorphic torso phantom with radioactive inserts ((90)Y) was acquired by SPECT-CT. Constant calibration factors (cps/MBq) for the quantification were evaluated, considering different volume, shape, position inside the phantom, activity concentration and background, and distance from detectors. S-voxel values (EGSnrc) were implemented in MATLAB R0086 USA software. Dose comparisons between S-voxel and the conventional Medical Internal Radiation Dose method were repeated in a group of 11 patients administered with (90)Y-DOTATATE.

Results: Using the appropriate calibration factors to recover the volume variability, the error about the measurement repeatability and the activity variation was within 4%. The variability of activity quantification, depending on the position in the phantom, detector distance, and background, was <10%, <5%, and <10%, respectively. The absorbed-dose values calculated by OLINDA were in agreement with the mean dose values obtained by the S-voxel method (difference, <10%).

Conclusions: The results confirm that, with the hybrid SPECT-CT system, quantitative analysis of SPECT (90)Y-Bremsstrahlung images and the generation of three-dimensional dose distributions are feasible. The improved analysis of Bremsstrahlung images could have a notable clinical impact, allowing to address the dosimetric verification to patients during the course of therapy.

MeSH terms

  • Algorithms
  • Calibration
  • Dose-Response Relationship, Radiation
  • Humans
  • Imaging, Three-Dimensional / methods
  • Kidney / radiation effects
  • Phantoms, Imaging
  • Radiometry / methods*
  • Radiopharmaceuticals*
  • Radiotherapy Dosage
  • Reproducibility of Results
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tomography, X-Ray Computed / methods*
  • Yttrium Radioisotopes*


  • Radiopharmaceuticals
  • Yttrium Radioisotopes