Evaluation of Dose Calculation Accuracy of Isogray Treatment Planning System in Craniospinal Radiotherapy

Document Type : Original Paper


1 Medical Physics Department, Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.

2 M.S.c of Mashhad University of Medical Sciences, Medical Physics Research Center, Mashhad, Iran

3 Associate Professor of Medical Physics, Research Center of Medical Physics, Mashhad University of Medical Sciences, Mashhad, Iran

4 Medical Physics Dept, Faculty of Medicine, Mashhad University of Medical Sciences


Introduction: Craniospinal radiotherapy is a therapeutic technique for central nervous system (CNS) tumors, which requires meticulous attention to technique and dosimetry.Treatment planning system (TPS) is one of the main equipment in radiotherapy; therefore, the evaluation of its accuracy is essential for dose calculation. The present study evaluates the validity of Isogray TPS in craniospinal irradiation techniques.
Material and Methods: The computed tomography (CT) images of the brain and spine of the Rando phantom were acquired. Two techniques were designed. In technique 1, the whole CNS was irradiated with 6 MV photon beam. In technique 2, the brain and spine were irradiated with 6 MV photon and 18 MeV electron beam, respectively. The tumor and organs at risk doses were measured by thermoluminescent dosimeter (TLD). In addition, photon and electron dose measurements inside and outside the treatment field were accomplished using TLD, and then compared to the corresponding values calculated by TPS.
Results: According to the results, in both electron and photon beams, the differences between the doses calculated by TLD and TPS for the points inside the treatment field were less than 4% for 90% of the measurement points. However, for the points outside the treatment field borders, the differences ranged within 10-40%. These differences were indicative of the sufficient dosimetric accuracy of Isogray TPS.
Conclusion: The comparison of dosimetry results with those of TPS results revealed the accuracy of Isogray TPS. In both techniques, the maximum difference between the TLD- and TPS-measured doses was observed in the mandible.


Main Subjects

  1. Newton HB. Primary brain tumors: review of etiology, diagnosis and treatment. Amer fam phys. 1994; 49(4):  787-97.
  2. Levitt SH, Purdy JA, Perez CA, Vijayakumar S. Technical basis of radiation therapy. Springer; 2012.
  3. Berry MP, Jenkin RD, Keen CW, Nair BD, Simpson WJl. Radiation treatment for medulloblastoma: a 21-year review. J neuro. 1981; 55(1):  43-51.
  4. Garton GR, Schomberg PJ, Scheithauer BW, Shaw EG, Ilstrup DM, Blackwell CR. Medulloblastoma—prognostic factors and outcome of treatment: review of the Mayo Clinic experience. in Mayo Clinic Proceedings. 1990 ; 65: 1077-86.
  5. Maor MH. Fields RS, Hogstrom KR, Van Eys J. Improving the therapeutic ratio of craniospinal irradiation in medulloblastoma. Int J Radiat Oncol* Biol* Phys. 1985; 11(4): 687-97.
  6. McMillan T. In vitro radiosensitivity of human medulloblastoma cell lines. J neuro-oncol. 1993; 15(1):  91-2.
  7. Lu L. Dose calculation algorithms in external beam photon radiation therapy. Int J Cancer Ther and Onco. 2013; 1(2) : 1-19
  8. Westermann C, B. Mijnheer, and H. Van Kleffens. Determination of the accuracy of different computer planning systems for treatment with external photon beams. Radiother and Oncol. 1984; 1(4): 339-47.
  9. Rosenow UF. Quality assurance in treatment planning, in use comput radiother. 1987 ; 36-               51.
  10. Wittkamper  F, Mijnhee  B , Van Kleffens H. Dose intercomparison at the radiotherapy centres in The Netherlands. Photon beams under reference conditions and for prostatic cancer treatment. Radiother and Onco. 1987; 9(1): 33-44.
  11. Mollazadeh M, Allahverdi M, Allahverdi Pourfallah T, Riahi Alam N, Ay M. Evaluation of the RtDosePlan Treatment Planning System using Radiochromic Film and Monte Carlo Simulation. Iranian J Med Phys. 2010;7(2):81-93.
  12. Howell RM, Scarboro SB, Kry S, Yaldo DZ. Accuracy of out-of-field dose calculations by a commercial treatment planning system. Physics in medicine and biology. 2010;55(23):6999.
  13. Weber DC, Peguret N, Dipasquale G, Cozzi L. Involved-node and involved-field volumetric modulated arc vs. fixed beam intensity-modulated radiotherapy for female patients with early-stage supra-diaphragmatic Hodgkin lymphoma: a comparative planning study. Int J Radiat Oncol* Biol* Phys. 2009;75(5):1578-86.
  14. Aspradakis MM, Morrison RH, Richmond ND, Steele A. Experimental verification of convolution/superposition photon dose calculations for radiotherapy treatment planning. Phys med biol. 2003; 48(17): 2873.
  15. Fogliata A, Nicolini G, Vanetti E, Clivio A, Cozzi L. Dosimetric validation of the anisotropic analytical algorithm for photon dose calculation: fundamental characterization in water. Phys med biol. 2006; 51(6): 1421.
  16. Huyskens D, Van Esch A, Pyykkonen J, Tenhunen M, Hannu Helminen H, Tillikainen L, et al. Improved photon dose calculation in the lung with the analytical anisotropic algorithm (AAA). in Radiother and Oncol. 2006; 81:513
  17. Breitman K, Rathee S, Newcomb C, Murray B, Robinson D, Field C, et al. Experimental validation of the Eclipse AAA algorithm. Journal of Applied Clinical Medical Physics. 2007 ;8(2):76-92.
  18. Sievinen J, Ulmer W, Kaissl W. AAA photon dose calculation model in Eclipse. Palo Alto (CA): Varian Medical Systems. 2005;118:2894.
  19. Baghani HR, Aghamiri SM, Gharaati H, Mahdavi SR, Hosseini DS. Comparing the results of 3D treatment planning and practical dosimetry in craniospinal radiotherapy using Rando phantom. Iran J Rad Res. 2011; 9(3): 25-31.
  20. Hood C, Kron T, Hamilton C, Callan S, Howlett S, Alvaro F, Back M. Correlation of 3D-planned and measured dosimetry of photon and electron craniospinal radiation in a pediatric anthropomorphic phantom. Radiotherapy and Oncology. 2005 Oct 1;77(1):111-6.
  21. Toossi MT, Soleymanifard S, Farhood B, Farkhari A, Knaup C. Evaluation of electron dose calculations accuracy of a treatment planning system in radiotherapy of breast cancer with photon-electron technique.2018.
  22. Pemler P, Besserer J, Schneider U, Neuenschwander H. Evaluation of a commercial electron treatment planning system based on Monte Carlo techniques (eMC). Zeitschrift für medizinische Physik. 2006 Jan 1;16(4):313-29.
  23. Remoto RZ, Corpuz JD. Quality Assurance of Pinnacle Treatment Planning System for External Beam Radiotherapy. in World Cong Med Phys Biomed Eng. 2013;70:1876-9.