Comparison of CCC and ETAR dose calculation algorithms in pituitary adenoma radiation treatment planning; Monte Carlo evaluation

• Published in: Journal of radiotherapy in practice Vol. 13; no. 4; pp. 447 - 455
• Main Authors: Tanha, K., Mahdavi, S. R., Geraily, G.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.12.2014
• Subjects: Original Articles; ETAR; dose calculation algorithm; CCC; treatment planning system; Monte Carlo simulation
• ISSN: 1460-3969; 1467-1131
• DOI: 10.1017/S1460396914000211

Abstract Aims To verify the accuracy of two common absorbed dose calculation algorithms in comparison to Monte Carlo (MC) simulation for the planning of the pituitary adenoma radiation treatment. Materials and methods After validation of Linac's head modelling by MC in water phantom, it was verified in Rando phantom as a heterogeneous medium for pituitary gland irradiation. Then, equivalent tissue-air ratio (ETAR) and collapsed cone convolution (CCC) algorithms were compared for a conventional three small non-coplanar field technique. This technique uses 30 degree physical wedge and 18 MV photon beams. Results Dose distribution findings showed significant difference between ETAR and CCC of delivered dose in pituitary irradiation. The differences between MC and dose calculation algorithms were 6.40 ± 3.44% for CCC and 10.36 ± 4.37% for ETAR. None of the algorithms could predict actual dose in air cavity areas in comparison to the MC method. Conclusions Difference between calculation and true dose value affects radiation treatment outcome and normal tissue complication probability. It is of prime concern to select appropriate treatment planning system according to our clinical situation. It is further emphasised that MC can be the method of choice for clinical dose calculation algorithms verification.