IMRT implementation and patient specific dose verification with film and ion chamber array detectors

• Authors: Sathiyan Saminathan , Ravikumar Manickam , Varatharaj Chandraraj , Sanjay Supe , Subbarao Keshava
• Languages of publication: EN

Abstracts

EN

Implementation of Intensity Modulation Radiotherapy (IMRT) and patient dose verification was carried out with film and I'mariXX using linear accelerator with 120-leaf Millennium dynamic multileaf collimator (dMLC). The basic mechanical and electrical commissioning and quality assurance tests of linear accelerator were carried out. The leaf position accuracy and leaf position repeatability checks were performed for static MLC positions. Picket fence test and garden fence test were performed to check the stability of the dMLC and the reproducibility of the gap between leaves. The radiation checks were performed to verify the position accuracy of MLCs in the collimator system. The dMLC dosimetric checks like output stability, average leaf transmission and dosimetric leaf separation were also investigated. The variation of output with gravitation at different gantry angles was found to be within 0.9%. The measured average leaf transmission for 6 MV was 1.6% and 1.8% for 18 MV beam. The dosimetric leaf separation was found to be 2.2 mm and 2.3 mm for 6 MV and 18 MV beams. In order to check the consistency of the stability and the precision of the dMLC, it is necessary to carryout regular weekly and monthly checks. The dynalog files analysis for Garden fence, leaf gap width and step wedge test patterns carried out weekly were in good agreement. Pretreatment verification was performed for 50 patients with ion chamber and I'matiXX device. The variations of calculated absolute dose for all treatment fields with the ion chamber measurement were within the acceptable criterion. Treatment Planning System (TPS) calculated dose distribution pattern was comparable with the I'matriXX measured dose distribution pattern. Out of 50 patients for which the comparison was made, 36 patients were agreed with the gamma pixel match of > 95% and 14 patients were with the gamma pixel match of 90-95% with the criteria of 3% delta dose (DD) and 3 mm distance-to-agreement (DTA). Commissioning and quality assurance of dMLC for IMRT application requires considerable time and effort. Many dosimetric characteristics need to be assessed carefully failing which the delivered dose will be significantly different from the planned dose. In addition to the issues discussed above we feel that individual MU check is necessary before the treatment is delivered.

Keywords

EN

IMRT; dMLC; quality assurance; I'matriXX; DTA; delta dose

• Publisher: Versita
• Journal: Polish Journal of Medical Physics And Engineering
• Year: 2009
• Volume: 15
• Issue: 2
• Pages: 87-102

Dates

published

1 - 1 - 2009

online

22 - 9 - 2010

Contributors

author

Sathiyan Saminathan

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

Ravikumar Manickam

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

Varatharaj Chandraraj

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

Sanjay Supe

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

Subbarao Keshava

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

References

• Bayouth JE, Wendt D, Morrill SM. MLC quality assurance technique for IMRT applications. Med Phys. 2003; 30(5): 743-750.[Crossref][PubMed]
• Bohsung J, Groll J, Moys A, Bohmer D, Marnitz S, Budach V. One year of clinical IMRT with dynamic MLC - the Charite experience from a physicist point of view. Proceedings of the 9th Varian European Users Meeting; 2001: 39-45.
• Chui C-S, Spirou S, LoSasso T. Testing of dynamic multileaf collimation. Med Phys. 1996; 23(5): 635-641.[Crossref][PubMed]
• Deshpande D D, Kinhikar R A, Sherly S, Ghosh S, Srivastava S K, Dinshaw K A. Quality Assurance (QA) and implementation of intensity modulated radiotherapy (IMRT) with dynamic multileaf collimator (DMLC) on 2100 C/D linear Accelerator. J Med Phys. 2002; 27(2): 41-50.
• Dinesh Kumar M, Thirmavalavan N, Venugopal Krishna D, Babaiah M. QA of intensity modulation beams using dynamic MLC log files. J Med Phys. 2006; 31(1): 36-41.[Crossref]
• Essers M, de Langen M, Dirkx MLP, Heijmen BJM. Commissioning of a commercially available system for intensity-modulated radiotherapy dose delivery with dynamic multileaf collimation. Radiother Oncol. 2001; 60: 215-224.[Crossref]
• Gary A. Ezzell, Jay W. Burmeister, Nesrin Dogan, Thomas J. LoSasso, James G. Mechalakos and Dimitris Mihailidis et al. IMRT commissioning: Multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119. Med Phys. 2009; 36(11): 5359-5373.[WoS]
• Intensity Modulated Radiation Therapy Collaborative Working Group, Intensity-modulated radiotherapy: Current status and issues of interes. Int J Radiat Oncol Biol Phys. 2001; 51(4): 880-914.
• Kallman P, Lind B, Eklof A, Brahme A. Shaping of arbitrary dose distribution by dynamic multileaf collimation. Phys Med Biol. 1998; 33: 1291-1300.
• Klein EE, Hanley J, Bayouth J, Yin FF, Simon W and Dresser S et al. Task Group 142 report: quality assurance of medical accelerators Med Phys. 2009; 36(9): 4197-212.
• LoSasso T, Chui C-S, Ling C. Physical and dosimetric aspects of a multileaf collimation system used in the dynamic mode for implementing intensity modulated radiotherapy. Med Phys. 1998; 25(10): 1919-1927.[PubMed][Crossref]
• LoSasso T, Chui C-S, Ling C. Comprehensive quality assurance for the delivery of intensity modulated radiotherapy with a multileaf collimator used in the dynamic mode. Med Phys. 2001; 28(11): 2209-2219.[Crossref][PubMed]
• 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.[Crossref]
• Ravichandran R, Binukumar J P, Sivakumar S S, Krishnamurthy K, Davis C A. A method for estimation of accuracy of dose delivery with dynamic slit windows in medical linear accelerators. J Med Phys. 2008; 33(3): 127-129.[PubMed][Crossref]
• Sivakumar S S, Krishnamurthy K, Davis, R Ravichandran C A, Kannadhasan S, Binukumar J P, Kamal EI Ghamrawy. Clinical implementation of dynamic intensity modulated radiotherapy: Dosimetric aspects and initial experience. J Med Phys. 2008; 33(2): 64-71.[Crossref]
• Van Esch A, Bohsung J, Sorvari P, et al. Acceptance test and quality control (QC) procedures for the clinical implementation of intensity modulated radiotherapy (IMRT) using inverse planning and sliding window technique: Experience from five radiotherapy departments. Radiother Oncol. 2002; 60: 53-70.

Identifiers

DOI

10.2478/v10013-009-0009-5