Lung compensator design using an electronic portal imaging device

Parsaei, Homayoon; Hussein, Sherali; El‐Khatib, Ellen

doi:10.1016/s0958-3947(98)00050-8

Cited by 4 publications

(1 citation statement)

References 11 publications

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“…Exit dosimetry has also proven to be a useful approach to the verification of dynamic collimation, intensity modulated fields, 26 -34 as well as compensator design 35,36 with the goal of comparing the integrated dose with the planned dose distribution. In addition, the patient mid-plane or exit dose can be predicted from the portal dose if a 3D CT data-set is known and the model for calculating the exit portal dose is accurate.…”

Section: Introductionmentioning

confidence: 99%

An investigation of a new amorphous silicon electronic portal imaging device for transit dosimetry

2002

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The relationship between the pixel value and exit dose was investigated for a new commercially available amorphous silicon electronic portal imaging device. The pixel to dose mapping function was established to be linear for detector distances between 116.5 cm to 150 cm from the source, radiation field sizes from 5 x 5 cm2 to 20 x 20 cm2 and beam energies of 6 to 18 MV. Coefficients in the mapping function were found to be dependent on beam energy and field size. Open and wedged field profiles measured with the device showed agreement to a maximum of 5% and 8%, respectively, as compared to film. A comparison of relative transmission measurements between the EPID and ion chamber indicate a maximum deviation of 6% and 2% at 6 and 18 MV, respectively, for an attenuator thickness of 21 cm and SDD > or = 130 cm. It was found that accuracies of better than 1% could be obtained if detector position and field size specific fitting parameters were used to generate unique mapping functions for each configuration.

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Section: Introductionmentioning

confidence: 99%

An investigation of a new amorphous silicon electronic portal imaging device for transit dosimetry

2002

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Portal image contrast enhancement

Shirazi

Mahdavi

Sardari

et al. 2006

Reports of Practical Oncology & Radiotherapy

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Analytical calculation of the portal scatter to primary dose ratio: an EGS4 Monte Carlo and experimental validation at large air gaps

Ozard

Grein

2001

Phys. Med. Biol.

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An analytical approximation for the scatter to primary dose ratio (SPR) on the central axis was validated against Monte Carlo results and experimental measurements for homogeneous and inhomogeneous phantoms. The analytical approximation only included first-order Compton scatter. The contribution to the total SPR from first-order Compton scatter, multiply scattered photons and electron scatter was investigated using Monte Carlo simulation for homogeneous phantoms (up to 30 cm thick for 6 and 18 MV beams; source to detector distances from 150 to 230 cm) as well as for a neck, thorax and pelvis phantom. SPRs were measured on the central axis with an ionization chamber for water phantoms (up to 20 cm thick at 4 MV, 30 cm for 6 MV and 10 MV and 40 cm for 18 MV; source to detector distances of 185 and 200 cm) and for phantoms representing the neck, thorax and pelvis (for air gaps of 50 cm and larger). The mean difference between the experimental and analytical SPRs on the central axis for source to detector distances of 170 cm or greater was within: -0.003 (neck); -0.012 (thorax); -0.028 (pelvis, 10 MV) and 0.008 (pelvis, 18 MV) respectively.

show abstract

Lung compensator design using an electronic portal imaging device

Cited by 4 publications

References 11 publications

An investigation of a new amorphous silicon electronic portal imaging device for transit dosimetry

An investigation of a new amorphous silicon electronic portal imaging device for transit dosimetry

Portal image contrast enhancement

Analytical calculation of the portal scatter to primary dose ratio: an EGS4 Monte Carlo and experimental validation at large air gaps

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