Quality Assurance of TPS: comparison of dose calculation for stereotactic patients in Eclipse and iPlan RT Dose

Abstract

Background

Quality assurance (QA) in the radiation therapy planning process is essential to ensure accurate dose delivery to the patient and to minimize the possibility of accidental exposure. In recent years, several reports have been developed addressing issues related to the commissioning and quality assurance (QA) of RTPSs.

Aim

To evaluate the differences between dose distributions obtained with different dose calculation algorithms implemented in TPSs for stereotactic irradiation.

Materials and Methods

BrainLab's iPlan v. 3.0.2 RT Dose calculates by pencil beam algorithm, while Eclipse v.7.5.18 (Varian Medical Systems) calculates by different types of pencil beam/AAA algorithms (selectable).

Results

The largest difference was found in the lung patient, where a difference of 10.3% in the number of monitor units and 8.3% in dose to the isocentre occurred (with calculation by AAA algorithm of Eclipse in relation to iPlan PB algorithm). The average difference in all other cases (AAA compared to iPlan) was 2.2% for MUs and 1.5% for dose to the isocentre. The average difference in all other cases (PB compared to iPlan) was 1.9% for MUs and 3.2% for dose to the isocentre. When data were transferred from iPlan through DICOM RT to Eclipse, for all patients an isocentre shift was observed.

Conclusion

The dose distribution calculated by three different photon calculation algorithms results in clinically significant dose differences in isodose distribution, especially in the area of high inhomogeneities.