Katarina Sjögreen, Michael Ljungberg, Karin Wingårdh, David Minarik, Sven-Erik Strand

A new method for absorbed dose assessment in radionuclide therapy is presented and applied to patients undergoing radioimmuno- therapy by monoclonal antibodies labeled with ¹¹¹In/⁹⁰Y. The method is based on activity quantification by the conjugate-view methodology, applied to serial whole-body anterior- posterior scintillation-camera scans. The quantification method is an extension of previous work, and includes separate corrections for attenuation, scatter and overlapping organs. Further development has now been undertaken to take into account the capabilities of new dual-head camera systems with an in built x-ray- tube for anatomical imaging. Furthermore, modeling of time- activity data is included, and dosimetric calculations based on the formalism by the Medical Internal Radiation Dose committee. To streamline absorbed dose assessments for large number of patient studies, the programs for quantification, image registration, and absorbed dose calculations have been embedded in an envelop program termed LundADose where calculations to a great extent are performed automatic.