Evaluation of single-photon emission computed tomography images obtained with and without copper filter by segmentation.

Background: Measurement of accurate attenuation of photon flux in tissue is important to obtain reconstructed images using single-photon emission computed tomography (SPECT). Computed tomography (CT) scanner provides attenuation correction data for SPECT as well as anatomic information for diagnostic purposes. Segmentation is a process of dividing an image into regions having similar properties such as gray level, color, texture, brightness, and contrast.

A new method to correct the attenuation map in simultaneous transmission/emission tomography using Gd/Ga radioisotopes.

Reconstruction of the tomographic images without attenuation correction can cause erroneously high count densities and reduced image contrast in low attenuation regions. In order to solve the problem of photon attenuation, one needs to know the attenuation coefficient for the individual patient being studied. Therefore, we made an attempt to correct the attenuation map in simultaneous transmission/emission tomography with (153)Gd/(67)Ga using maximum likelihood method using the expectation maximization (ML-EM) algorithm to correct the transmission window for both the spillover and downscatter.

An investigation of a sinogram discontinuity artifact on myocardial perfusion imaging.

Unlabelled: Our purpose was to find out the cause of an unusual distinct break seen on a patient's sinogram despite within-tolerance results on all quality assurance tests during myocardial perfusion imaging (MPI) and corrective measures.

Methods: SPECT quality control is a prerequisite to obtaining high-quality diagnostic images. Daily uniformity and energy-peaking tests and weekly center-of-rotation (COR) tests are run to check the performance of the SPECT system.

Radiochromic film dosimetry of rectal inhomogeneity and applicator attenuation in high dose rate brachytherapy of uterine cervix.

Heterogeneities existing in the patient during treatment are neglected, as the treated subject is considered homogeneous in most of the commercially-available treatment planning systems (TPSs) used for high dose rate (HDR) brachytherapy. The choice of a suitable dosimeter for experimental dosimetry near the HDR source is crucial, mainly due to existence of steep dose gradients. The present work aimed to assess the effect of rectal air heterogeneity and applicator attenuation in the HDR Ir-192 brachytherapy treatment of carcinoma uterine cervix by utilizing GAFCHROMIC EBT2 film dosimetry.

Evaluation of Gafchromic EBT2 film for the measurement of anisotropy function for high-dose-rate (192)Ir brachytherapy source with respect to thermoluminescent dosimetry.

Aim: The aim of this work was to assess the suitability of the use of a Gafchromic EBT2 film for the measurement of anisotropy function for microSelectron HDR (192)Ir (classic) source with a comparative dosimetry method using a Gafchromic EBT2 film and thermoluminescence dosimeters (TLDs).

Background: Sealed linear radiation sources are commonly used for high dose rate (HDR) brachytherapy treatments. Due to self-absorption and oblique filtration of radiation in the source capsule material, an inherent anisotropy is present in the dose distribution around the source which can be described by a measurable two-dimensional anisotropy function, F(r, θ).