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Number of results
2009 | 15 | 2 | 87-102

Article title

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

Content

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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

Publisher

Year

Volume

15

Issue

2

Pages

87-102

Physical description

Dates

published
1 - 1 - 2009
online
22 - 9 - 2010

Contributors

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

References

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  • 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.

Document Type

Publication order reference

Identifiers

YADDA identifier

bwmeta1.element.-psjd-doi-10_2478_v10013-009-0009-5
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