Patient-specific dosimetry calculations using mathematic models of different anatomic sizes during therapy with 111In-DTPA-D-Phe1-octreotide infusions after catheterization of the hepatic artery.
The aim of the study was to provide dosimetric data on intrahepatic (111)In-diethylenetriaminepentaacetic acid (DTPA)-D-Phe(1)-octreotide therapy for neuroendocrine tumors with overexpression of somatostatin receptors.


METHODS
A dosimetric protocol was designed to estimate the absorbed dose to the tumor and healthy tissue in a course of 48 treatments for 12 patients, who received a mean activity of 5.4 +/- 1.7 GBq per session. The patient-specific dosimetry calculations, based on quantitative biplanar whole-body scintigrams, were performed using a Monte Carlo simulation program for 3 male and 3 female mathematic models of different anatomic sizes. Thirty minutes and 2, 6, 24, and 48 h after the radionuclide infusion, blood-sample data were collected for estimation of the red marrow radiation burden.


RESULTS
The mean absorbed doses per administered activity (mGy/MBq) by the critical organs liver, spleen, kidneys, bladder wall, and bone marrow were 0.14 +/- 0.04, 1.4 +/- 0.6, 0.41 +/- 0.08, 0.094 +/- 0.013, and (3.5 +/- 0.8) x 10(-3), respectively; the tumor absorbed dose ranged from 2.2 to 19.6 mGy/MBq, strongly depending on the lesion size and tissue type.


CONCLUSIONS
The results of the present study quantitatively confirm the therapeutic efficacy of transhepatic administration; the tumor-to-healthy-tissue uptake ratio was enhanced, compared with the results after antecubital infusions. Planning of treatment was also optimized by use of the patient-specific dosimetric protocol.
Kontogeorgakos
Dimitrios K
DK
Radiology Department, Nuclear Medicine Division, Aretaieion University Hospital, Athens, Greece.
Dimitriou
Panagiotis A
PA
Limouris
Georgios S
GS
Vlahos
Lambros J
LJ
D000328:Adult; D000368:Aged; D001822:Body Burden; D049628:Body Size; D003198:Computer Simulation; D005260:Female; D006499:Hepatic Artery / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007261:Infusions, Intra-Arterial; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011874:Radiometry / Q000379:methods*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013004:Somatostatin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use
D019275:Radiopharmaceuticals; D013004:Somatostatin; C081788:pentetreotide