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Dosimetry limitations and pre-treatment dose profile correction for sliding window IMRT
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G. Grigorov   , J.C.L. Chow , N. Yazdani |
| , grigor.grigorov@grhosp.on.ca |
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Abstract: (12569 Views) |
| Background: This work investigated the
dosimetry limitations of the random and systematic
uncertainties of sliding window (SW) intensity
modulated radiation therapy (IMRT). Materials and
Methods: A Varian 21EX linear accelerator, Pinnacle3
treatment planning system and radiographic film
dosimetry was used. The limitations of the SW were
studied using beam modulation ranging from 2 to
100 MU/beam, DR from 100 to 600 MU min-1, LV
from 1 to 5 cm s-1 and field size up to 12 × 12 cm2.
The random and systematic errors were investigated
using clinical and flat beams, as well as beams of
high profile modulation including linear, exponential,
and sinusoidal profiles. Results: The leading edge
and plateau of the SW profiles have a significant
deformation for higher DR and for beams of < 10
MUs/beam. It was found that the error is directly
proportional to the DR and LV, and inversely proportional
to the number of MU/beam. Conclusion: The
high DR and LV are limiting factors, producing
random profile deformation when SW beams of small
number of MU/beam are delivered. A very good
agreement was found between the planned and
delivered geometrical and clinical dose profiles when
beams > 10 MUs irradiated by a DR from 100 to 600
MU min-1 and LV from 1 to 5 cm s-1. After the
proposed correction, an average difference < 0.5%
for clinical profiles was measured for beams
irradiated with DR = 600 MU min-1 and LV= 5 cm s-1.
It was concluded that this correction methodology
may serve as a pre-treatment Quality Assurance tool
for SW IMRT beams. Iran. J. Radiat. Res., 2010 8 (2):
61-74 |
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| Keywords: IMRT, sliding window, pre-treatment QA and pre-treatment dose correction. |
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Full-Text [PDF 546 kb]
(3956 Downloads)
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Type of Study: Original Research |
Subject:
Radiation Biology
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