Clinical Implications of TiGRT Algorithm for External Audit in Radiation Oncology

Shahbazi-Gahrouei, Daryoush; Saeb, Mohsen; Monadi, Shahram; Jabbari, Iraj

Clinical Implications of TiGRT Algorithm for External Audit in Radiation Oncology

Document Type : Original Article

Authors

¹ Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

² Department of Nuclear Engineering, Faculty of Advanced Sciences and Technologies, Isfahan University, Isfahan, Iran

Abstract

Background: Performing audits play an important role in quality assurance program in radiation oncology. Among different algorithms, TiGRT is one of the common application software for dose calculation. This study aimed to clinical implications of TiGRT algorithm to measure dose and compared to calculated dose delivered to the patients for a variety of cases, with and without the presence of inhomogeneities and beam modifiers. Materials and Methods: Nonhomogeneous phantom as quality dose verification phantom, Farmer ionization chambers, and PC-electrometer (Sun Nuclear, USA) as a reference class electrometer was employed throughout the audit in linear accelerators 6 and 18 MV energies (Siemens ONCOR Impression Plus, Germany). Seven test cases were performed using semi CIRS phantom. Results: In homogeneous regions and simple plans for both energies, there was a good agreement between measured and treatment planning system calculated dose. Their relative error was found to be between 0.8% and 3% which is acceptable for audit, but in nonhomogeneous organs, such as lung, a few errors were observed. In complex treatment plans, when wedge or shield in the way of energy is used, the error was in the accepted criteria. In complex beam plans, the difference between measured and calculated dose was found to be 2%–3%. All differences were obtained between 0.4% and 1%. Conclusions: A good consistency was observed for the same type of energy in the homogeneous and nonhomogeneous phantom for the three-dimensional conformal field with a wedge, shield, asymmetric using the TiGRT treatment planning software in studied center. The results revealed that the national status of TPS calculations and dose delivery for 3D conformal radiotherapy was globally within acceptable standards with no major causes for concern.

Keywords

References

1.	Lu L. Dose calculation algorithms in external beam photon radiation therapy. Int J Cancer Ther Oncol 2013;1:01025.
2.	Ulmer W, Pyyry J, Kaissl W. A 3D photon superposition/convolution algorithm and its foundation on results of Monte Carlo calculations. Phys Med Biol 2005;50:1767-90.
3.	TecDoc, I. 1583: Commissioning of Radiotherapy Treatment Planning Systems: Testing for Typical External Beam Treatment Techniques. Vienna: International Atomic Energy Agency; 2008.
4.	Ahnesjö A, Aspradakis MM. Dose calculations for external photon beams in radiotherapy. Phys Med Biol 1999;44:R99-155.
5.	Nadealian Dastjerdi F, Shahbazi-Gahrouei D, Alamatsaz MH, Baradaran-Ghahfarokhi M. Photoneutron shielding design for an 18 MV Saturne 20 medical linear accelerator. J Isfahan Med Sch 2014;32:1433-43.
6.	Rezaee V, Shahbazi-Gahrouei D, Monadi S, Saeb M. Evaluation of error doses of treatment planning software using solid anthropomorphic phantom. J Isfahan Med Sch2016;34:908-13.
7.	Shahbazi-Gahrouei D, Gookizadeh A, Abdolahi M. Comparison of conventional radiotherapy techniques with different energies in treating prostate cancer, employing a designed pelvis phantom. J Med Sci 2008;8:429-32.
8.	Sharpe MB. IAEA Technical Reports Series No. 430: Commissioning and quality assurance of computerized planning systems for radiation treatment of cancer. Med Phys 2006;33:561.
9.	Laliena Bielsa V, Millan Cebrian E, Garcia Romero A, Cortes Rodicio J, Villa Gazulla D, Ortega Pardina P, et al. Quality assurance of computerized planning systems for radiotherapy treatments according the IAEA-TECDOC-1583: Application to PCRT3D. Rev Fis Med 2012;13:89-96.
10.	Lopes MC, Cavaco A, Jacob K, Madureira L, Germano S, Faustino S, et al. Treatment planning systems dosimetry auditing project in Portugal. Phys Med 2014;30:96-103.
11.	Rutonjski L, Petrovic B, Baucal M, Teodorovic M, Cudic O, Gershkevitsh E, et al. Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit. Radiat Oncol 2012;7:155.
12.	Dunn L, Lehmann J, Lye J, Kenny J, Kron T, Alves A, et al. National dosimetric audit network finds discrepancies in AAA lung inhomogeneity corrections. Phys Med 2015;31:435-41.
13.	Mesbahi A, Dadgar H. Dose calculations accuracy of TiGRT treatment planning system for small IMRT beamlets in heterogeneous lung phantom. Int J Radiat Res 2015;13:345-54.
14.	Knöös T, Wieslander E, Cozzi L, Brink C, Fogliata A, Albers D, et al. Comparison of dose calculation algorithms for treatment planning in external photon beam therapy for clinical situations. Phys Med Biol 2006;51:5785-807.
15.	IAEA T. 398. Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water. Vienna International Atomic Energy Agency; 2000.
16.	TECDOC I. 1540. Specification and Acceptance Testing of Radiotherapy Treatment Planning Systems. Vienna: IAEA; 2007.

Advanced Biomedical Research