An integral transport equation-based industrial radiography simulation code is parallelized using the Message Passing Interface standard on computers with both distributed- and shared-memory architectures. The algorithm involves partitioning of the problem domain into regions that are connected to each other through interface conditions. This results in a simultaneous set of integral transport equations. Each equation in the set is assigned to a different processor in the platform. The new algorithm is subjected to scalability tests in both cluster and shared-memory architectures for a varying number of processors with different problem domain partition strategies. The results show a high level of scalability with favorable results in both architectures.