Assessment of two different dose distribution algorithms (Clarkson and Superposition) in PCRT3D treatment planning system for Esophagus Cancer by using 3DCRT technique

Document Type : Conference Proceedings


1 Medical physicist of Iran Mehr Radiotherapy Oncology Department, Iran Mehr Hospital, Birjand, Iran.

2 Professor of Medical Physics, Department of Medical Physics Shahid Sadoughi University of Medical Sciences, Yazd, Iran.

3 Medical physicist of Imam Reza Radiotherapy Oncology Department, Imam Reza Hospital, Mashhad, Iran.

4 Radiation Oncologist of Iran Mehr Radiotherapy Oncology Department, Iran Mehr Hospital, Birjand, Iran.

5 Medical Physicist of Sina Radiotherapy Oncology Department, Bu Ali Hospital, Tehran, Iran.


Introduction: The functionality and quality of any treatment planning system (TPS) strongly depends on the type of Algorithm which is used by it. Obviously, the role of dose distribution algorithms in calculation of prescribed dose inside the tumor in modern radiotherapy techniques has more important than past to achieve the best clinical outcomes, especially in tumors which are placed in lung or near it like Esophagus cancer.
The aim of this study is to evaluate and comparison of efficiency and accuracy of two dose distribution algorithms, Clarkson and Superposition which are using in PCRT 3D treatment planning system to calculate the dose distribution in Three- Dimensional Conformal Radiotherapy (3D-CRT) for Esophagus cancer cases.
Materials and Methods: In this study ten patients with esophageal cancer were planned by Clarkson and Superposition algorithms. Treatment plan of the patients were created with a photon beam of 6 MV. Commercially available PCRT3D version6 (made in Spain) Planning system was used to calculate dose in ten planed patients. For this goal and to compare two dose distribution algorithms, the statistical analysis was performed by comparing Conformity Index and Homogeneity Index for target.
Results: The maximum value of variation between algorithms for PTV in Dmin, Dmax, and Dmean were 11.7%, 8.3% and 0.73%, respectively. The maximum deviation of variation observed between algorithms in OAR's consist of Dmean is 8.9% for Left lung 7.14% for Right Lung and 2.65% for Spinal cord. Significant variation between algorithms for Homogeneity Index values is 9.06% and highest Percentage oscillation between algorithms for Conformity Index values are 6.33%.
Conclusion: According to this study and because of the different results which was driven from treatment planning, significant care should be taken account when calculating treatment plans, due to different dose calculation algorithm may influence treatment planning as well as clinical results.