# Approach to radionuclide therapy dosimetry planning

10/02/2016 2016 - #03 Nuclear medicine and biology

Lysak Yu.V. Dyomin V.M. Klimanov V.A. Narkevich B.Ya. Romodanov V.L.

### UDC: 539.07, 616.71

Control of radiation dose absorbed in the nidus represents one of the challenging issues in the implementation of radionuclide therapy (RNT).
Approach is presented in the present study to the assessment of the value of activity of the radiopharmaceutical (RPH) accumulated in the tumor based on the obtained planar scintigraphic images of the patient’s body and calculation of radiation transfer by Monte-Carlo method taking into account the processes of absorption and scattering in the patient’s biological tissues and elements of the gammachamber structure.
The phases in the obtaining the required data included simulation of scintigraphic study in the gammachamber of the vial containing RPH activity injected to the patient located at the fixed distance from the collimator and implementation of similar study with identical measurement geometry in the conditions when the same value of RPH activity is introduced in the nidus inside the patient’s body.
Adapted Fischer-Snyder human body phantom was used in the MCNP input file for obtaining corresponding calculation results.
Calculation was performed within the framework of the above model for different nidus dimensions and different depths of tumor positioning inside the patient’s body for the case of application of RPH on the basis of both mixed β-γemitting (^{131}I, ^{177}Lu) and pure β-emitting (^{89}Sr, ^{90}Y) therapeutic radionuclides.
The described methodology allows implementing with sufficient accuracy the assessment of doses absorbed within the zones of interest on the basis of the data of patient’s planar stratigraphy.

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radionuclide therapy Monte-Carlo method radiopharmaceuticals control of basic doses planar stratigraphy