VOLUME 19 (Supplement)

Monte Carlo simulation of Co-60 gamma irradiation using P-TReCK for deep-seated soft tissue dosimetry

Cobalt-60 (Co-60) remains a fundamental radioisotope for clinical radiotherapy, where accurate dose calculations in deep-seated soft tissues require detailed modeling of photon transport complexities. This study evaluates the Photon Transport and Response Characterization Kit (P-TReCK, version 1.0.1) for simulated 2D energy deposition mapping in a two-layer heterogeneous cylindrical phantom consisting of adipose and soft tissue. Axial and radial profiles were generated under broad disk and central pencil beam configurations and benchmarked against PHITS (v3.36) simulations. Spatial and dosimetric agreement were assessed using the Dose Uniformity Ratio (DUR), Mean Absolute Percentage Error (MAPE), and a 1D global gamma index analysis (2% dose difference, 2 mm distance-to-agreement). Under these criteria, P-TReCK achieved a 100% gamma pass rate and maintained sub-percent MAPE values across all configurations. The calculated DUR values agreed within their propagated uncertainties. These benchmark results demonstrate that P-TReCK’s primary-interaction algorithm accurately reproduces depth-dose attenuation and lateral scatter in macroscopic low-Z tissues, providing a computational baseline for future extension to patient-specific geometries.