| dc.description.abstract | Introduction: Antibody-radionuclide-conjugate therapy using the monoclonal antibody
agent 177 Lu-DOTA-HH1 (BetalutinTM ) developed by Nordic Nanovector, is a novel treatment of Non-Hodgkin s Lymphoma. A Phase I/II study is currently being conducted at Oslo University Hospital, the Lymrit-37-01-study. The main aim of this thesis was to develop and present a method to do dosimetric calculations on tumors in patients included in the study. Inhomogeneity of dose was investigated through dose rate maps and cumulative dose rate histograms.
Method: Using imaging data from two SPECT/CT-sessions 4 and 7 days post-injection,
activity in lesions was quantified. Volumes of interest (VOIs) were drawn by a nu-
clear medicine specialist. VOIs were drawn with a margin around the imaged activity
of the lesion, the novel VOISPECT -method. Cumulative activity was found through mono-
exponential clearance of the activity. Patient specific masses from VOIs closely around
the tumors were used. Absorbed dose was found by the proposed S-factor, S,resulting
in mean dose to the tumors. The activity quantification method was verified through
phantom measurements with hot spheres in attenuating material. The energy absorption
factor was found using the dose calculation computer program OLINDA. Dose rate maps
were generated through the use of convolution of activity distribution and a voxel s-value kernel retrieved from a database.
Result: A total of 17 tumors in 6 patients grouped in three dose levels were ascribed
a mean dose. Mean doses ranged from 86 to 794cGy. Inter- and intra-patient
differences were observed. The phantom experiment showed good accuracy, with relative
errors in the order of 5% compared to true activity. A constant factor S ̄ to calculate the
cumulative energy was found sufficient as long as tumor volumes are in the range 1mL to
300mL. 16 dose rate maps and cumulative dose rate volume histograms were made, and
D-values were found. Conclusion: The method presented was found to be successful in the calculation of mean tumor dose. A method to generate dose rate maps and cumulative dose rate histograms has also been found and presented. | |
