Conventional versus virtual simulation for radiation treatment planning of prostate cancer: final results

Radiotherapy is widely used to treat patients with prostate cancer. Using conventional x-ray simulation is often difficult to accurately localize the extent of the tumor, to cover exactly the lymph nodes at risk and shield the organs at risk. We report on the results of a study comparing target localization with conventional and virtual simulation.

One hundred prostate cancer patients underwent both conventional and virtual simulation. The conventional simulation films were compared with digitally reconstructed radiographs (DDRs) produced from the computed tomography (CT) data. All patients underwent target localization for radical prostate radiotherapy. The treatment fields were initially marked with a conventional portal film on linear accelerator (LINAC), plain x-ray film and available diagnostic imaging. Each patient then had a CT and these simulated treatment fields were reproduced within the virtual simulation planning system. The treatment fields defined by the clinicians using each modality were compared in terms of field area and implications for target coverage.

Virtual simulation showed significantly greater clinical tumor volume coverage and less normal tissue volume irradiated compared with conventional simulation (p <0.001).

CT localization and virtual simulation allow more accurate definition of the clinical target volume. This could enable a reduction in geographical misses, reducing at the same time treatment-related toxicity.