Image quality improvement in megavoltage cone beam CT using an imaging beam line and a sintered pixelated array system

Abstract

Since CNR scales with the square root of imaging dose, changing from TBL + LFB to IBL + LFB and IBL + LFB to IBL + SPA reduces the imaging dose required to obtain a given CNR by factors of 0.38 and 0.37, respectively. MTFs were comparable between imaging system configurations. IBL + SPA patient image quality was always better than that of the TBL + LFB system and as good as or better than that of the IBL + LFB system, for a given dose.

The effect of copper conversion plates on low‐Z target image quality

“…Similar factor increases are seen for the 7.00 MV/carbon beam, but as for the planar imaging results, CNR values are typically half of that observed at 2.35 MV/carbon. The CNR improvement with copper removal seen here is comparable in magnitude to the factor 1.64 gain in CNR observed by Breitbach et al 18 when using a segmented ceramic Gb 2 S 2 O scintillator, compared to a standard 1.0 mm copper conversion plate with Gb 2 S 2 O scintillating phosphor. However, this group used a different beam-line 7 within a Siemens linac at 4.2 MV.…”

Volume-of-interest cone-beam CT using a 2.35 MV beam generated with a carbon target

“…The modification of the photon spectrum enhances differential attenuation in patient tissues thereby improving contrast, and the approach may be coupled with use of a higher efficiency detector for further improvement of contrast-to-noise (CNR) in imaging. 6,9 While the degree of improvement in image quality depends on the beam line and detector designs, we have shown previously, for example, that compared to 6 MV imaging, use of a 3.5 MeV electron beam incident on an aluminum target yields an improvement of CNR by factors ranging from 2.7 to 4.3 in cone beam CT (CBCT) images. Alternatively, for the same CNR, imaging dose may be reduced approximately by a factor of ∼8.…”

Image quality and dose distributions of three linac-based imaging modalities

“…Several studies have evaluated the image quality and dosimetric properties of the various modalities [5][6][7]13,15,25,29], but to date these techniques have not been compared with respect to imaging dose and dose distribution. We therefore present dose distributions from these techniques both for planar and CBCT imaging, for patients with prostate cancer and head-and-neck cancer.…”