Monte Carlo investigation of single cell beta dosimetry for intraperitoneal radionuclide therapy

Abstract

Single event spectra for five beta-emitting radionuclides (Lu-177, Cu-67, Re-186, Re-188, Y-90) were calculated for single cells from two source geometries. The first was a surface-bound isotropically emitting point source and the second was a bath of free radioactivity in which the cell was submerged. Together these represent a targeted intraperitoneal radionuclide therapy. Monoenergetic single event spectra were calculated over an energy range of 11 keV to 2500 keV using the EGSnrc Monte Carlo system. Radionuclide single event spectra were constructed by weighting monoenergetic single event spectra according to radionuclide spectra appropriate for each source geometry. In the case of surface-bound radioactivity, these were radionuclide beta decay spectra. For the free radioactivity, a continuous slowing down approximation spectrum was used that was calculated based on the radionuclide decay spectra. The frequency mean specific energy per event increased as the energy of the beta emitter decreased. This is because, at these energies, the stopping power of the electrons decreases with increasing energy. The free radioactivity produced a higher frequency mean specific energy per event than the corresponding surface-bound value. This was primarily due to the longer mean path length through the target for this geometry. This information differentiates the radionuclides in terms of the physical process of energy deposition and could be of use in the radionuclide selection procedure for this type of therapy.

Calculation of electron and isotopes dose point kernels with fluka Monte Carlo code for dosimetry in nuclear medicine therapy

“…Specific tools have been developed with MCNPX 33,34 to perform the patient-specific calculations for nuclear medicine dosimetry or to derive data useful for radionuclide therapies. 35 Differences among the codes can be expected due to the different simulation algorithms. ETRAN, GEANT4, and MCNPX are all "condensed history" Monte Carlo codes.…”

The COOLER Code: A Novel Analytical Approach to Calculate Subcellular Energy Deposition by Internal Electron Emitters

“…Because detailed simulation of electron tracks can be time consuming, condensed history transport codes have often been employed to approach various cellular dosimetric problems (26)(27)(28)(29)(30)(31)(32). Among the shortcomings of using condensed history codes, we point out the adoption of large energy cutoff for electron transport, typically between 1 and 10 keV, which results in a spatial resolution of the order of the biological target.…”

177Lu/153Sm-Ethylenediamine Tetramethylene Phosphonic Acid Cocktail: A Novel Palliative Treatment for Patients with Bone Metastases

“…3,12,20 Lutetium-177 [T 1/2 = 6.73 d, E bmax = 497 keV, E c = 113 keV (6.4%), 208 keV (11%)] is an alternative option with several advantages, 21 such as lower bparticle energy resulting in minimum bone marrow suppression 17,22 and relatively long physical half-life permitting adequate tumor irradiation dose with a constant dose rate. 23,24 Hence,…”