The Quality Control of Intensity Modulated Radiation Therapy (IMRT) for ONCOR Siemens Linear Accelerators Using Film Dosimetry

Document Type : Original Paper


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

2 Radiation Oncologist, Department of Radiation-Oncology, Isfahan Milad Hospital, Isfahan, Iran


Intensity Modulated Radiation Therapy (IMRT) has made a significant progress in radiation therapy centers in recent years. In this method, each radiation beam is divided into many subfields that create a field with a modulated intensity. Considering the complexity of this method, the quality control for IMRT is a topic of interest for researchers. This article is about the various steps of planning and quality control of Siemens linear accelerators for IMRT, using film dosimetry. This article in addition to review of the techniques, discusses the details of experiments and possible sources of errors which are not mentioned in the protocols and other references.
Materials and Methods
This project was carried out in Isfahan Milad hospital which has two Siemens ONCOR linear accelerators. Both accelerators are equipped with Multi-Leaf Collimators (MLC) which enables us to perform IMRT delivery in the step-and-shoot method. The quality control consists of various experiments related to the sections of radiation therapy. In these experiments, the accuracy of some components such as treatment planning system, imaging device (CT), MLC, control system of accelerator, and stability of the output are evaluated. The dose verification is performed using film dosimetry method. The films were KODAK-EDR2, which were calibrated before the experiments. One of the important steps is the comparison of the calculated dose with planning system and the measured dose in experiments.
The results of the experiments in various steps have been acceptable according to the standard protocols. The calibration of MLC and evaluation of the leakage through the leaves of MLC was performed by using the film dosimetry and visual check. In comparison with calculated and measured dose, more that 80% of the points have to be in agreement within 3% of the value. In our experiments, between 85 and 90% of the points had such an agreement with IMRT delivery.
The EDR2 films are suitable for quality control of IMRT. According to complexity of the quality control for IMRT, the physicists of each center have to develop specific guidelines according to their equipments and limitations. An accurate treatment planning system with capability of inverse planning is an essential need for IMRT. The result of the planning system has to be compared with experiments in various situations.   


Main Subjects

  1. Ezzell GA, Burmeister JW, Dogan N, LoSasso TJ, Mechalakos JG, Mihailidis D, et al. IMRT commissioning: multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119. Med Phys. 2009;36(11):5359-73.
  2. Ezzell GA, Galvin JM, Low D, Palta JR, Rosen I, Sharpe MB, et al. Guidance document on delivery, treatment planning, and clinical implementation of IMRT: report of the IMRT Subcommittee of the AAPM Radiation Therapy Committee. Med Phys. 2003;30(8):2089-115.
  3. Poppe MM, Narra V, Yue NJ, Zhou J, Nelson C, Jabbour SK. A Comparison of Helical Intensity-Modulated Radiotherapy, Intensity-Modulated Radiotherapy, and 3D-Conformal Radiation Therapy for Pancreatic Cancer. Med Dosim.
  4. Zhou GX, Xu SP, Dai XK, Ju ZJ, Gong HS, Xie CB, et al. Clinical dosimetric study of three radiotherapy techniques for postoperative breast cancer: Helical Tomotherapy, IMRT, and 3D-CRT. Technol Cancer Res Treat. 2011;10(1):15-23.
  5. Kim T, Zhu L, Suh TS, Geneser S, Meng B, Xing L. Inverse planning for IMRT with nonuniform beam profiles using total-variation regularization (TVR). Med Phys. 2010;38(1):57-66.
  6. Bortfeld T. IMRT: a review and preview. Phys Med Biol. 2006;51(13):R363-79
  7. Palta JR, Deye JA, Ibbott GS, Purdy JA, Urie MM. Credentialing of institutions for IMRT in clinical trials. Int J Radiat Oncol Biol Phys. 2004;59(4):1257-9; author reply 9-61.
  8. Oliver M, Chen J, Wong E, Van Dyk J, Perera F. A treatment planning study comparing whole breast radiation therapy against conformal, IMRT and tomotherapy for accelerated partial breast irradiation. Radiother Oncol. 2007;82(3):317-23.
  9. Ahnesjo A, Hardemark B, Isacsson U, Montelius A. The IMRT information process-mastering the degrees of freedom in external beam therapy. Phys Med Biol. 2006;51(13):R381-402.
  10. Holmes T, Das R, Low D, Yin FF, Balter J, Palta J, et al. American Society of Radiation Oncology recommendations for documenting intensity-modulated radiation therapy treatments. Int J Radiat Oncol Biol Phys. 2009;74(5):1311-8.
  11. Huq MS, Fraass BA, Dunscombe PB, Gibbons JP, Jr., Ibbott GS, Medin PM, et al. A method for evaluating quality assurance needs in radiation therapy. Int J Radiat Oncol Biol Phys. 2008;71(1 Suppl):S170-3.
  12. Cheng CW, Das IJ. Comparison of beam characteristics in intensity modulated radiation therapy (IMRT) and those under normal treatment condition. Med Phys. 2002;29(2):226-30.
  13. Das IJ, Cheng CW, Chopra KL, Mitra RK, Srivastava SP, Glatstein E. Intensity-modulated radiation therapy dose prescription, recording, and delivery: patterns of variability among institutions and treatment planning systems. J Natl Cancer Inst. 2008;100(5):300-7.
  14. Galvin JM, Ezzell G, Eisbrauch A, Yu C, Butler B, Xiao Y, et al. Implementing IMRT in clinical practice: a joint document of the American Society for Therapeutic Radiology and Oncology and the American Association of Physicists in Medicine. Int J Radiat Oncol Biol Phys. 2004;58(5):1616-34.
  15. Low DA, Sohn JW, Klein EE, Markman J, Mutic S, Dempsey JF. Characterization of a commercial multileaf collimator used for intensity modulated radiation therapy. Med Phys. 2001;28(5):752-6.
  16. McGarry CK, Butterworth KT, Trainor C, O'Sullivan J M, Prise KM, Hounsell AR. Temporal characterization and in vitro comparison of cell survival following the delivery of 3D-conformal, intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Phys Med Biol. 2011;56(8):2445-57.
  17. Mackie TR. History of tomotherapy. Phys Med Biol. 2006;51(13):R427-53.
  18. Langen KM, Papanikolaou N, Balog J, Crilly R, Followill D, Goddu SM, et al. QA for helical tomotherapy: report of the AAPM Task Group 148. Med Phys.37(9):4817-53.
  19. Yang R, Xu S, Jiang W, Xie C, Wang J. Integral dose in three-dimensional conformal radiotherapy, intensity-modulated radiotherapy and helical tomotherapy. Clin Oncol (R Coll Radiol). 2009;21(9):706-12.
  20. Cheek D, Gibbons JP, Rosen, II, Hogstrom KR. Accuracy of TomoTherapy treatments for superficial target volumes. Med Phys. 2008;35(8):3565-73.
  21. Fraser D, Parker W, Seuntjens J. Characterization of cylindrical ionization chambers for patient specific IMRT QA. J Appl Clin Med Phys. 2009;10(4):2923.
  22. Parker W, Filion E, Roberge D, Freeman CR. Intensity-modulated radiotherapy for craniospinal irradiation: target volume considerations, dose constraints, and competing risks. Int J Radiat Oncol Biol Phys. 2007;69(1):251-7.
  23. Heath E, Seuntjens J, Sheikh-Bagheri D. Dosimetric evaluation of the clinical implementation of the first commercial IMRT Monte Carlo treatment planning system at 6 MV. Med Phys. 2004;31(10):2771-9.
  24. Li JS, Lin T, Chen L, Price RA, Jr., Ma CM. Uncertainties in IMRT dosimetry. Med Phys.37(6):2491-500.
  25. Bayouth JE. Siemens multileaf collimator characterization and quality assurance approaches for intensity-modulated radiotherapy. Int J Radiat Oncol Biol Phys. 2008;71(1 Suppl):S93-7.
  26. Bhangle JR, Sathiya Narayanan VK, Deshpande SA. Dose linearity and uniformity of Siemens ONCOR impression plus linear accelerator designed for step-and-shoot intensity-modulated radiation therapy. J Med Phys. 2007;32(3):103-7.
  27. Munter MW, Thilmann C, Hof H, Didinger B, Rhein B, Nill S, et al. Stereotactic intensity modulated radiation therapy and inverse treatment planning for tumors of the head and neck region: clinical implementation of the step and shoot approach and first clinical results. Radiother Oncol. 2003;66(3):313-21.
  28. Okumura M, Obata Y, Shimomura K, Tamura M, Nishimura Y. The effect of gantry and collimator angles on leaf limited velocity and position in dynamic multileaf collimator intensity-modulated radiation therapy. Phys Med Biol.55(11):3101-13.
  29. Boyer AL, Li S. Geometric analysis of light-field position of a multileaf collimator with curved ends. Med Phys. 1997;24(5):757-62.
  30. Graves MN, Thompson AV, Martel MK, McShan DL, Fraass BA. Calibration and quality assurance for rounded leaf-end MLC systems. Med Phys. 2001;28(11):2227-33.
  31. Zhu XR, Jursinic PA, Grimm DF, Lopez F, Rownd JJ, Gillin MT. Evaluation of Kodak EDR2 film for dose verification of intensity modulated radiation therapy delivered by a static multileaf collimator. Med Phys. 2002;29(8):1687-92.
  32. Childress NL, Salehpour M, Dong L, Bloch C, White RA, Rosen, II. Dosimetric accuracy of Kodak EDR2 film for IMRT verifications. Med Phys. 2005;32(2):539-48.
  33. Childress NL, Rosen, II. Effect of processing time delay on the dose response of Kodak EDR2 film. Med Phys. 2004;31(8):2284-8.
  34. Morrell RE, Rogers A. Calibration of Kodak EDR2 film for patient skin dose assessment in cardiac catheterization procedures. Phys Med Biol. 2004;49(24):5559-70.
  35. Shi C, Papanikolaou N, Yan Y, Weng X, Jiang H. Analysis of the sources of uncertainty for EDR2 film-based IMRT quality assurance. J Appl Clin Med Phys. 2006;7(2):1-8.
  36. Khan FM. The Physics of Radiation Therapy. 4th ed. Baltimore, MD Lippincott Williams & Wilkins; 2009.
  37. Khan FM. Treatment Planning in Radiation Oncology. 2nd ed. Baltimore, MD Lippincott Williams & Wilkins; 2006.
  38. LinaTech, TiGRT TPS Radiation Treatment Planning System. Available from: Accessed date: Sep 20, 2010.
  39. Van Lin EN, Futterer JJ, Heijmink SW, van der Vight LP, Hoffmann AL, van Kollenburg P, et al. IMRT boost dose planning on dominant intraprostatic lesions: gold marker-based three-dimensional fusion of CT with dynamic contrast-enhanced and 1H-spectroscopic MRI. Int J Radiat Oncol Biol Phys. 2006;65(1):291-303.
  40. Alexander A, Deblois F, Stroian G, Al-Yahya K, Heath E, Seuntjens J. MMCTP: a radiotherapy research environment for Monte Carlo and patient-specific treatment planning. Phys Med Biol. 2007;52(13):N297-308.
  41. Grofsmid D, Dirkx M, Marijnissen H, Woudstra E, Heijmen B. Dosimetric validation of a commercial Monte Carlo based IMRT planning system. Med Phys. 2010;37(2):540-9.
  42. Pisaturo O, Moeckli R, Mirimanoff RO, Bochud FO. A Monte Carlo-based procedure for independent monitor unit calculation in IMRT treatment plans. Phys Med Biol. 2009;54(13):4299-310.
  43. Siebers JV, Kawrakow I, Ramakrishnan V. Performance of a hybrid MC dose algorithm for IMRT optimization dose evaluation. Med Phys. 2007;34(7):2853-63.
  44. Momennezhad M, Bahreyni Toossi MT,  Gholamhoseinian H, An Assessment of Dose Distribution for Asymmetric Fields by Monte Carlo Simulation. Iran Jour of Med Phys 2008; 18(5): 73-80.
  45. Moslemi V, Esmaili-Torshabi A, Mosleh-Shirazi MA, Faghihi R, Mosalaei A, Mehdizadeh S, Hadad K. CT-BasedBrachytherapy Treatment Planning using Monte Carlo Simulation Aided by an Interface Software. Iran Jour of Med Phys 2011; 30(8): 41-53.
  46. Palta JR, Liu C, Li JG. Current external beam radiation therapy quality assurance guidance: does it meet the challenges of emerging image-guided technologies? Int J Radiat Oncol Biol Phys. 2008;71(1 Suppl):S13-7.         
  47. Palta JR, Liu C, Li JG. Quality assurance of intensity-modulated radiation therapy. Int J Radiat Oncol Biol Phys. 2008;71(1 Suppl):S108-12.
  48. Van Dyk J, Barnett RB, Cygler JE, Shragge PC. Commissioning and quality assurance of treatment planning computers. Int J Radiat Oncol Biol Phys. 1993;26(2):261-73.
  49. Jursinic PA, Sharma R, Reuter J. MapCHECK used for rotational IMRT measurements: step-and-shoot, TomoTherapy, RapidArc. Med Phys. 2010;37(6):2837-46.
  50. Fraass B, Doppke K, Hunt M, Kutcher G, Starkschall G, Stern R, et al. American Association of Physicists in Medicine Radiation Therapy Committee Task Group 53: quality assurance for clinical radiotherapy treatment planning. Med Phys. 1998;25(10):1773-829.
  51. Kutcher GJ, Coia L, Gillin M, Hanson WF, Leibel S, Morton RJ, et al. Comprehensive QA for radiation oncology: report of AAPM Radiation Therapy Committee Task Group 40. Med Phys. 1994;21(4):581-618.
  52. Low DA, Harms WB, Mutic S, and Purdy JA. A technique for the quantitative evaluation of dose distributions. Med. Phys. 1998;25(5):656-61.
  53. Chui CS, Chan MF, Yorke E, Spirou S, Ling CC. Delivery of intensity-modulated radiation therapy with a conventional multileaf collimator: comparison of dynamic and segmental methods. Med Phys. 2001;28(12):2441-9.
  54. Grigorov GN, Chow JC, Barnett RB. Dosimetry limitations and a dose correction methodology for step-and-shoot IMRT. Phys Med Biol. 2006;51(3):637-52.
  55. Mohr P, Brieger S, Stahl J, Witucki G. Linearity of the dose monitor system at low monitor units. Strahlenther Onkol. 2007;183(6):327-31.
  56. Kluter S, Sroka-Perez G, Schubert K, Debus J. Leakage of the Siemens 160 MLC multileaf collimator on a dual energy linear accelerator. Phys Med. 2010;Biol.56(2):N29-37.
  57. Purdy JA. Dose to normal tissues outside the radiation therapy patient's treated volume: a review of different radiation therapy techniques. Health Phys. 2008;95(5):666-76.
  58. Hardcastle N, Metcalfe P, Ceylan A, Williams MJ. Multileaf collimator end leaf leakage: implications for wide-field IMRT. Phys Med Biol. 2007;52(21):N493-504.
  59. Kamali-Asl A, Batooli AH, Harriri S, Salman-Rezaee F, Shahmardan F, Yavari L, Design, Simulation and Manufacture of a Multileaf Collimator to Confirm the Target Volumes in Intensity Modulated Radiation Therapy. Iran Jour of Med Phys 2010; 26(7): 65-74.
  60. Both S, Alecu IM, Stan AR, Alecu M, Ciura A, Hansen JM, et al. A study to establish reasonable action limits for patient-specific quality assurance in intensity-modulated radiation therapy. J Appl Clin Med Phys. 2007;8(2):1-8.
  61. Mosleh-Shirazi MA, Safe and Judicious Use of Advanced Radiotherapy Techniques and Equipment: A Medical Physicist's Perspective on Recent Accident Reports. Middle East J Cancer 2010;1(2):59-63