The effect of non-rigid misregistration in sequential quantitative SPECT for targeted radionuclide therapy - A simulation study

Greta S.P. Mok, Edwin C.I. Ao, Na Song, Eric C. Frey

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Non-rigid organ misregistration is an important problem for patients undergoing sequential quantitative SPECT for 3D dosimetry for targeted radionuclide therapy (TRT) treatment planning. This study aims to evaluate effects of these misregistrations on the accuracy of 3D dosimetry. We used 3 anatomical variations and 3 respective In-111 Zevalin distributions of the digital 4D Extended Cardiac Torso (XCAT) phantom to model the deformation in different organs such as liver, kidneys, spleen and stomach. We simulated SPECT scans acquired at 5 time points, i.e., 1, 12, 24, 72 and 144 hrs post-injection of 111In Zevalin. Organs with uniform activity concentrations were randomly translated and rotated within 5 pixels/degrees, while the change of the total volume of each organ was within 5% except for the stomach. The 24-hr scan served as a reference. An analytical projector modeling attenuation, scatter and the geometric collimator-detector-response of a medium energy collimator was used to generate noisy projections representing a realistic count level for 128 views over 360°. Reconstructed images were obtained using OS-EM with attenuation, scatter and geometric collimator-detector-response compensation. Voxel-by-voxel integration over different time points followed by convolution with a 90Y dose kernel was used to generate 3D dose distribution images. For each phantom, we compared the organ dose and its dose volume histogram (DVH) for (i) no organ deformation and (ii) organs with deformation. The mean difference of organ doses between two sets of images were 3.88%, -6.73%, -7.32% and -14.42% for lung, liver, kidneys and spleen respectively. However, even for the organs with dose errors <5%, the associated normalized absolute errors in DVH were >10%. We conclude that organ misregistration and deformation are important factors in limiting accuracy of 3D dosimetric quantities and whole body non-rigid registration of sequential quantitative SPECT is essential for accurate TRT treatment planning.

Original languageEnglish (US)
Title of host publication2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012
Pages2938-2941
Number of pages4
DOIs
StatePublished - Dec 1 2012
Event2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012 - Anaheim, CA, United States
Duration: Oct 29 2012Nov 3 2012

Publication series

NameIEEE Nuclear Science Symposium Conference Record
ISSN (Print)1095-7863

Other

Other2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012
CountryUnited States
CityAnaheim, CA
Period10/29/1211/3/12

ASJC Scopus subject areas

  • Radiation
  • Nuclear and High Energy Physics
  • Radiology Nuclear Medicine and imaging

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    Mok, G. S. P., Ao, E. C. I., Song, N., & Frey, E. C. (2012). The effect of non-rigid misregistration in sequential quantitative SPECT for targeted radionuclide therapy - A simulation study. In 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012 (pp. 2938-2941). [6551671] (IEEE Nuclear Science Symposium Conference Record). https://doi.org/10.1109/NSSMIC.2012.6551671