Assessment of Radiation Therapy Dose Distribution Using Digitally Reconstructed Radiograph.

Introduction: The DRR has typically been employed for verifying the geometry in radiotherapy treatment, and there have been no documented instances of its use for dosimetric purposes. This research aims to introduce a new methodology, allowing us to generate a two - dimensional dose distribution within a treatment plan using the DRR for the first time. Methods: First, the study will investigate the relationship between the pixel values of the DRR and water - equivalent thickness (WET). Next, it aims to establish a link between depth and absorbed dose. By combining these relationships, a new equation will be developed to connect the pixel values of the DRR to the absorbed dose. This method will be utilized to calculate the dose distribution in the isocentric plane for both homogeneous and heterogeneous phantoms. To verify the accuracy of this approach, the results will be compared with the two - dimensional dose distribution from the treatment planning system (TPS). Results: At the isocenter, the point dose comparison indicates a variance of around 1% for the homogeneous phantom and 1.2% for the heterogeneous phantom. A gamma analysis (3% - 3mm criteria) was conducted to compare the region - based dose distribution. The pass rate achieved was 98.44% for the homogeneous phantom and 96.6% for the heterogeneous phantom. Conclusions: Confirming the dose distribution derived from this method with TPS introduces a novel use of DRR for assessing dose distribution in perpendicular planes to the treatment field's central axis. This serves as a means for verifying treatment planning and a fresh approach to quality control in radiotherapy. [ABSTRACT FROM AUTHOR]