نتایج جستجو برای: attenuation correction

تعداد نتایج: 212408  

Journal: :Annals of nuclear medicine 2004
Yasuyuki Takahashi Kenya Murase Teruhito Mochizuki Hiroshi Higashino Yoshifumi Sugawara Akiyoshi Kinda

PURPOSE One of the main factors contributing to the accuracy of attenuation correction for SPECT imaging using transmission computed tomography (TCT) with an external gamma-ray source is the radionuclide count. To reduce deterioration of TCT images due to inadequate radionuclide counts, a correction method, segmented attenuation correction (SAC), in which TCT data are transformed into several c...

Journal: :Journal of Mathematical Imaging and Vision 2019

2006
Eugenio Gorgucci Luca Baldini

Although is not a major error source at C-band, attenuation may degrade the radar measurement to a considerable degree in situations like a precipitation event in the radar shadow of a strong convective cell, or may affect precipitation accumulation estimates at distances far from the radar site. For C-band radars, attenuation can be corrected using different methods depending on the type of me...

2004
A.

We describe a hybrid measured/calculated method for attenuation correction in positron emission tomography (PET). This unified reconstruction/segmentation method is based on a penalized weighted least-squares (PWLS) objective function that is minimized using iterative coordinate-descent (ICD). Two penalty functions are compared; one for a discrete object parameterization, the other for a contin...

Journal: :Human brain mapping 2015
Sophia Mueller Danhong Wang Michael D Fox Ruiqi Pan Jie Lu Kuncheng Li Wei Sun Randy L Buckner Hesheng Liu

Network properties can be estimated using functional connectivity MRI (fcMRI). However, regional variation of the fMRI signal causes systematic biases in network estimates including correlation attenuation in regions of low measurement reliability. Here we computed the spatial distribution of fcMRI reliability using longitudinal fcMRI datasets and demonstrated how pre-estimated reliability maps...

2017
Katarina Sjögreen Michael Ljungberg

For activity quantification based on planar scintillation camera measurements, photon attenuation is an important factor that needs to be corrected for in a patientand organ-specific manner. One possibility for obtaining attenuation correction maps is to use X-ray CT scout images. Since the intensity of scout images is in relative numbers, their image values need to be multiplied by a factor to...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 1998
P Maksud B Fertil C Rica G El Fakhri A Aurengo

UNLABELLED This study investigates the ability of artificial neural networks (ANN) to simultaneously correct for attenuation and Compton scattering in scintigraphic imaging. METHODS Three sets of experiments are conducted using images of radioactive sources with various shapes and distributions in a homogeneous medium. Numerical Monte Carlo simulations and physical phantom acquisitions of rad...

Journal: :Cancer biotherapy & radiopharmaceuticals 2012
Katarina Sjögreen Gleisner Michael Ljungberg

For activity quantification based on planar scintillation camera measurements, photon attenuation is an important factor that needs to be corrected for in a patient- and organ-specific manner. One possibility for obtaining attenuation correction maps is to use X-ray CT scout images. Since the intensity of scout images is in relative numbers, their image values need to be multiplied by a factor ...

2015
Lynn J. Frohwein Mirco Heß Florian Büther Klaus P. Schäfers

Erratum Unfortunately, the original version of this article [1] contained an error. The author list was included incorrectly. This can be found correctly listed above. Submit your manuscript to a journal and benefi t from: 7 Convenient online submission 7 Rigorous peer review 7 Immediate publication on acceptance 7 Open access: articles freely available online 7 High visibility within the fi el...

1999
Ing-Tsung Hsiao Wenli Wang

We introduced [1] a Bayesian method for transmission tomography that used a novel pointwise prior in the form of a mixture of gamma distributions. Here, we compare the performance our pointwise prior with that of a smoothing prior in the context of a weak tumor detection task for emission PET. The reprojected attenuation maps from each method are used for attenuation correction of 2D PET emissi...

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