1. bookVolume 15 (2009): Issue 2 (June 2009)
Journal Details
License
Format
Journal
eISSN
1898-0309
First Published
30 Dec 2008
Publication timeframe
4 times per year
Languages
English
access type Open Access

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

Published Online: 22 Sep 2010
Volume & Issue: Volume 15 (2009) - Issue 2 (June 2009)
Page range: 87 - 102
Journal Details
License
Format
Journal
eISSN
1898-0309
First Published
30 Dec 2008
Publication timeframe
4 times per year
Languages
English
IMRT implementation and patient specific dose verification with film and ion chamber array detectors

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

Bayouth JE, Wendt D, Morrill SM. MLC quality assurance technique for IMRT applications. Med Phys. 2003; 30(5): 743-750.10.1118/1.1564091Search in Google Scholar

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.Search in Google Scholar

Chui C-S, Spirou S, LoSasso T. Testing of dynamic multileaf collimation. Med Phys. 1996; 23(5): 635-641.10.1118/1.597699Search in Google Scholar

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.Search in Google Scholar

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): 36-41.10.4103/0971-6203.25668Search in Google Scholar

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: 215-224.10.1016/S0167-8140(01)00317-6Search in Google Scholar

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): 5359-5373.10.1118/1.3238104Search in Google Scholar

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): 880-914.10.1016/S0360-3016(01)01749-7Search in Google Scholar

Kallman P, Lind B, Eklof A, Brahme A. Shaping of arbitrary dose distribution by dynamic multileaf collimation. Phys Med Biol. 1998; 33: 1291-1300.10.1088/0031-9155/33/11/0073231672Search in Google Scholar

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): 4197-212.10.1118/1.319039219810494Search in Google Scholar

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): 1919-1927.10.1118/1.5983819800699Search in Google Scholar

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): 2209-2219.10.1118/1.141012311764024Search in Google Scholar

Palta JR, Liu C, Li JG. Quality assurance of intensity modulated radiation therapy. Int J Radiat Oncol Biol Phys. 2008; 71(1 Suppl): S108-12.10.1016/j.ijrobp.2007.05.092Search in Google Scholar

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): 127-129.10.4103/0971-6203.42768Search in Google Scholar

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): 64-71.10.4103/0971-6203.41195Search in Google Scholar

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: 53-70.10.1016/S0167-8140(02)00174-3Search in Google Scholar

Recommended articles from Trend MD

Plan your remote conference with Sciendo