The effect of three dimensional activity distribution on the dose planning of radioimmunotherapy for patients with advanced intraperitoneal pseudomyxoma

Abstract

pseudomyxomas were treated with radioimmunotherapy. with single photon emission computed tomography (SPECT) at 3, 10, and 24 days after the therapeutic infusion. Treatment-planning software has been developed 2 Laboratory of Biomedical Engineering, Helin which functional information obtained from SPECT is integrated with anatomic sinki University of Technology, Espoo, Finland. METHODS.information obtained from computed tomography (CT). The activity distribution 3 Department of Oncology, Helsinki University from SPECT images is converted to absorbed dose distributions using a point Central Hospital, Helsinki, Finland.source kernel convolution dose calculation. The absorbed dose calculation requires 4 Department of Radiology, Helsinki University a radionuclide specific dose kernel. The activity map is divided into equally sized Central Hospital, Helsinki, Finland.source voxels from which the distribution is calculated for the target voxels that cover the patient volume. The resulting three dimensional (3D) absorbed dose distribution is viewed as isodose contours superimposed on the CT images or as 3D isodose surfaces. RESULTS.The measured activity distribution shows that the cumulated activity and biologic half-life vary in the patient's body. The developed planning system provides a method for calculating patient specific absorbed dose distributions. CONCLUSIONS. The variation of biologic clearance indicates that a 3D dose calcula-Presented at the Sixth Conference on Radioimtion method incorporating measured activity distributions is needed to quantify munodetection and Radioimmunotherapy of absorbed dose distribution. of management for cancer. 1There is a lack of accurate dosimetry in clinical RIT.

Comparison of four scatter correction methods for patient whole-body imaging during therapeutic trials with iodine-131

“…Evaluation of the efficiency of radioimmunotherapy (RIT), and more generally of targeted radiotherapy, depends on the precision of dosimetric studies. The current lack of dosimetric accuracy in RIT is due to the calculation models used and the difficulty of reaching a correct estimation of the activities taken up by organs on the basis of scintigraphic images 1. Thus, there is a need to optimize acquisition protocols and the processing of scintigraphic images.…”

Nuclear Medicine in Finland

“…[19] Radioimmunotherapy was introduced in Finland in 1994 for treating successfully intraperitoneal carcinomatoses, and for this purpose 3-D-dosimetry program was developed. [20] An interesting approach has been radiochemotherapy in head and neck cancer using In-111-BLMC, a tumor-targeting synergistically cytotoxic and radiotoxic compound, which was used in clinical trials. [21] This invention led to multiple inventions of creating multi-potential intelligent targeted nanoparticles for drug delivery.…”

The Impact of PET and SPECT on Dosimetry for Targeted Radionuclide Therapy

“…The disadvantage of planar imaging is the lack of threedimensional information. This can be partially solved by the addition of three-dimensional anatomical images from CT or MRI [28,[40][41][42][43][44][45]] although this will not yield the true 3D-distribution of radioactivity. As the conjugate view method cannot correct appropriately for overlapping tissues quantitative SPECT imaging leads to a more accurate determination of the actual tissue activity concentration.…”