Poster - 23: Dosimetric Characterization and Transferability of an Accessory Mounted Mini-Beam Collimator
Objective: The dosimetric characterization of an accessory-mounted mini-beam collimator across three beam matched linear accelerators. Materials and Methods: Percent depth dose and profiles were measured for the open and mini-beam collimated fields. The average beam quality and peak-to-valley dose r...
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Veröffentlicht in: | Medical physics (Lancaster) 2016-08, Vol.43 (8), p.4941-4941 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Objective:
The dosimetric characterization of an accessory-mounted mini-beam collimator across three beam matched linear accelerators.
Materials and Methods:
Percent depth dose and profiles were measured for the open and mini-beam collimated fields. The average beam quality and peak-to-valley dose ratio (PVDR), the ratio of average peak dose to average valley dose, were obtained from these measurements. The open field relative output and the mini-beam collimator factor, the ratio of the mini-beam dose to open field dose at the beam center, were measured for square fields of side 2, 3, 4, and 5 cm. Mini-beam output as a function of collimator inclination angle relative to the central axis was also investigated.
Results and Discussion:
Beam quality for both the open and mini-beam collimated fields agreed across all linacs to within ±1.0%. The PVDR was found to vary by up to ±6.6% from the mean. For the 2, 3, and 4 cm fields the average open field relative output with respect to the 5 cm field was 0.874±0.4%, 0.921±0.3%, and 0.962±0.1%. The average collimator factors were 0.450±3.9%, 0.443±3.9%, 0.438±3.9%, and 0.434±3.9%. A decrease in collimator factor greater than 7% was found for an inclination angle change of 0.09°.
Conclusion:
The mini-beam collimator has revealed a difference between the three linacs not apparent in the open field data, yet transferability can still be attained through thorough dosimetric characterization. |
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ISSN: | 0094-2405 2473-4209 |
DOI: | 10.1118/1.4961797 |