Intensity modulated radiation therapy (IMRT) verification using the frame averaging feature of Varian Mark II electronic portal imaging device (EPID) Conference Paper
| Authors: | Chang, J.; Mageras, G.; Ling, C. C. |
| Editor: | Enderle, J. D. |
| Title: | Intensity modulated radiation therapy (IMRT) verification using the frame averaging feature of Varian Mark II electronic portal imaging device (EPID) |
| Conference Title: | 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society |
| Abstract: | We have previously developed a dose-based IMRT verification system, but its usefulness is limited by the image acquisition and storage time of the Varian PoralVision EPID. In this study, we investigate the applicability of the EPID's frame-averaging feature to acquire ∼1 sec images and averages over them before storage. However, the frame-averaged image cannot be converted to a dose map due to the non-linearity of the EPID response. To circumvent this, we convert the dose rate from intensity-modulated (IM) beams to EPID readings and then sum over the simulated ∼1 sec images to produce the intended frame-averaged image (IFAI). Frame-averaged images (EFAI) are measured with an EPID for the same IM fields. We also simulated frame-averaged image (SFAI) by acquiring a series of individual images under the normal mode and summing them offline. The IFAI, EFAI and SFAI are then compared using a linear regression method, whose standard deviation of errors, σ, is a measure of the goodness of match. Artificial malfunctions were also introduced into IM beam delivery to test the sensitivity of this approach. The results indicate that SFAI agrees with IFAI with a mean σ = 3% and a standard deviation (SD) < 0.6%. EFAI, however, shows less agreement with IFAI with a mean σ = 4.1% and a SD of 1.5%. Most, but not all, simulated malfunctions were detectable using EFAIs. We conclude that the frame-averaging feature of Varian Mark II EPID shows promise for treatment verification, but that more investigation is required to validate this approach for clinical application. |
| Keywords: | intensity modulated radiation therapy; sensitivity analysis; radiotherapy; imrt; medical imaging; regression analysis; epid; errors; data acquisition; electronic portal imaging device; treatment verification; frame-averaging; framed average image |
| Journal Title | IEEE Engineering in Medicine and Biology Society. Annual International Conference. Proceedings |
| Volume: | 3 |
| Conference Dates: | 2000 Jul 23-28 |
| Conference Location: | Chicago, IL |
| ISBN: | 1094-687X |
| Publisher: | IEEE |
| Location: | Chicago, IL |
| Date Published: | 2000-01-01 |
| Start Page: | 2059 |
| End Page: | 2062 |
| Language: | English |
| PROVIDER: | scopus |
| DOI: | 10.1109/IEMBS.2000.900530 |
| DOI/URL: | |
| Notes: | Annu Int Conf IEEE Eng Med Biol Proc -- Conference code: 58180 -- Export Date: 18 November 2015 -- CODEN: CEMBA -- 23 July 2000 through 28 July 2000 -- Source: Scopus |
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