Monte Carlo Simulations Corroborate PET-Measured Discrepancies in Activity Assessments of Commercial Y Vials.

In a recent multicenter study, discrepancies between PET/CT-measured activity and vendor-calibrated activity for Y glass and resin microspheres were found. In the present work, the origin of these discrepancies was investigated by Monte Carlo (MC) simulations. Three vial configurations, containing Y-chloride, Y-labeled glass microspheres, and Y-labeled resin microspheres, were modeled with GAMOS, and the electric signal generated in an activity meter was simulated.

Updating Y Voxel S-Values including internal Bremsstrahlung: Monte Carlo study and development of an analytical model.

Purpose: Internal Bremsstrahlung (IB) is a process accompanying β-decay but neglected in Voxel S-Values (VSVs) calculation. Aims of this work were to calculate, through Monte Carlo (MC) simulation, updated Y-VSVs including IB, and to develop an analytical model to evaluate Y-VSVs for any voxel size of practical interest.

Methods: GATE (Geant4 Application for Tomographic Emission) was employed for simulating voxelized geometries of soft tissue, with voxels sides l ranging from 2 to 6 mm, in steps of 0.

Internal Bremsstrahlung, the missing process in beta decay Monte Carlo simulation: The relevance in P Dose-Point-Kernel estimation.

Purpose: In nuclear medicine, Dose Point Kernels (DPKs), representing the energy deposited all around a point isotropic source, are extensively used for dosimetry and are usually obtained by Monte Carlo (MC) simulations. For beta-decaying nuclides, DPK is usually estimated neglecting Internal Bremsstrahlung (IB) emission, a process always accompanying the beta decay and consisting in the emission of photons having a continuous spectral distribution. This work aims to study the significance of IB emission for DPK estimation in the case of P and provide DPK values corrected for the IB photon contribution.

F-PSMA-1007 salivary gland dosimetry: comparison between different methods for dose calculation and assessment of inter- and intra-patient variability.

. Simplified calculation approaches and geometries are usually adopted for salivary glands (SGs) dosimetry. Our aims were (i) to compare different dosimetry methods to calculate SGs absorbed doses (ADs) following [F]-PSMA-1007 injection, and (ii) to assess the AD variation across patients and single SG components.

Technical note: The contribution of internal bremsstrahlung to the Y dose point kernel.

Background: Internal dosimetry has an increasing role in the planning and verification of nuclear medicine therapies with radiopharmaceuticals. Dose Point Kernels (DPKs), quantifying the energy deposition all around a point source, in a homogenous medium, are extensively used for 3D dosimetry and nowadays are mostly evaluated by Monte Carlo (MC) simulation. To our knowledge, DPK for beta emitters is estimated neglecting the continuous photon emission due to the Internal Bremsstrahlung (IB), whose contribution to the absorbed dose can be relevant beyond the maximum range of betas, as evidenced in recent works.

An analytic model to calculate voxel s-values forLu.

.Lu is one of the most employed isotopes in targeted radionuclide therapies and theranostics, and 3D internal dosimetry for such procedures has great importance. Voxel S-Values (VSVs) approach is widely used for this purpose, but VSVs are available for a limited number of voxel dimensions.

Relevance of artefacts inTc-MAA SPECT scans on pre-therapy patient-specificY TARE internal dosimetry: a GATE Monte Carlo study.

The direct Monte Carlo (MC) simulation of radiation transport exploiting morphological and functional tomographic imaging as input data is considered the gold standard for internal dosimetry in nuclear medicine, and it is increasingly used in studies regarding trans-arterial radio-embolization (TARE). However, artefacts affecting the functional scans, such as reconstruction artefacts and motion blurring, decrease the accuracy in defining the radionuclide distribution in the simulations and consequently lead to errors in absorbed dose estimations. In this study, the relevance of such artefacts in patient-specific three-dimensional MC dosimetry was investigated in three cases ofY TARE.

Simplified patient-specific renal dosimetry in Lu therapy: a proof of concept.

Purpose: The aim of this proof-of-concept study is to propose a simplified personalized kidney dosimetry procedure in Lu peptide receptor radionuclide therapy (PRRT) for neuroendocrine tumors and metastatic prostate cancer. It relies on a single quantitative SPECT/CT acquisition and multiple radiometric measurements executed with a collimated external probe, properly directed on kidneys.

Methods: We conducted a phantom study involving external count-rate measurements in an abdominal phantom setup filled with activity concentrations of Tc, reproducing patient-relevant organ effective half-lives occurring in Lu PRRT.

Relevance of Internal Bremsstrahlung photons from Y decay: an experimental and Monte Carlo study.

Internal Bremsstrahlung (IB) is a continuous electromagnetic radiation accompanying beta decay; however, this process is not considered in radiation protection studies, particularly when estimating exposure from beta-decaying radionuclides. The aims of the present work are: i) to show that neglecting the IB process in Monte Carlo (MC) simulation leads to an underestimation of the energy deposited in a ionization chamber, in the case of a high-energy pure beta emitter such as Yttrium-90 (Y), and ii) to determine the most reliable choice of source term for Y IB to be used in MC simulations. For this radionuclide, commonly employed in nuclear medicine and radiochemistry applications, experimental data acquired with a well ionization chamber have been compared with Monte Carlo (MC) calculations carried out in the GAMOS framework.