Scatter rejection methods in megavoltage imaging with an amorphous-silicon flat-panel array

Groh, Burkhard A.; Spies, Lothar; Hesse, Bernd; Bortfeld, Thomas

doi:10.1117/12.384537

Cited by 4 publications

(2 citation statements)

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“…The only difference is that the BIS spectral response function is incorporated into the code. The BIS response, shown in figure 2, is estimated using the MC model detailed in Groh et al (2000). It comprises slabs of copper, polymethyl methacrylate (PMMA) and phosphor having the same dimensions as a detector pixel.…”

Section: Scatter Modelmentioning

confidence: 99%

Correction of scatter in megavoltage cone-beam CT

et al. 2001

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The role of scatter in a cone-beam computed tomography system using the therapeutic beam of a medical linear accelerator and a commercial electronic portal imaging device (EPID) is investigated. A scatter correction method is presented which is based on a superposition of Monte Carlo generated scatter kernels. The kernels are adapted to both the spectral response of the EPID and the dimensions of the phantom being scanned. The method is part of a calibration procedure which converts the measured transmission data acquired for each projection angle into water-equivalent thicknesses. Tomographic reconstruction of the projections then yields an estimate of the electron density distribution of the phantom. It is found that scatter produces cupping artefacts in the reconstructed tomograms. Furthermore, reconstructed electron densities deviate greatly (by about 30%) from their expected values. The scatter correction method removes the cupping artefacts and decreases the deviations from 30% down to about 8%.

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Section: Scatter Modelmentioning

confidence: 99%

Correction of scatter in megavoltage cone-beam CT

et al. 2001

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“…27 Figure 8 compares the AED obtained with the primary x-ray spectrum ͑dotted͒ with the AED calculated for the scatter spectrum ͑solid͒. Also, for equal primary and scatter fluences, the copper plate/phosphor screen over-responds to scattered photons as compared to water: 31 the probability that an incident x-ray deposits energy in the phosphor layer of the detector was 0.0357 and 0.067 for primary and scattered x rays, respectively. However, since the mean energy of scattered photons is lower, the mean energy deposited per incident scatter x-ray, obtained from the integration of the spectra shown in Fig.…”

Section: B Effect Of Scatter On Portal Image Qualitymentioning

confidence: 99%

Monte Carlo simulation of the image formation process in portal imaging

2003

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We have written Monte Carlo programs to simulate the formation of radiological images. Our code is used to propagate a simulated x-ray fluence through each component of an existing video-based portal imaging system. This simulated fluence consists of a 512 x 512 pixel image containing both contrast-detail patterns as well as checker patterns to assess spatial resolution of the simulated portal imager. All of the components of the portal imaging system were modeled as a cascade of eight linear stages. Using this code, one can assess the visual impact of changing components in the imaging chain by changing the appropriate probability density function. Virtual experiments were performed to assess the visual impact of replacing the lens and TV camera by an amorphous silicon array, and the effect of scattered radiation on portal images.

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Reducing the weight of the EC-L cassette

Munro

Mulligan

2002

International Journal of Radiation Oncology*Biology*Physics

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Scatter rejection methods in megavoltage imaging with an amorphous-silicon flat-panel array

Cited by 4 publications

References 0 publications

Correction of scatter in megavoltage cone-beam CT

Correction of scatter in megavoltage cone-beam CT

Monte Carlo simulation of the image formation process in portal imaging

Reducing the weight of the EC-L cassette

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