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Biomedical subjects

C Badea

Publications and source records attributed to C Badea.

8 recordsLinked to original sources
PubMed2001

Image quality in extended arc filtered digital tomosynthesis.

PURPOSE: To study image quality in filtered digital tomosynthesis (FDTS) tomograms as a function of their reconstruction arc, using isocentrically acquired, fluoroscopic projection data. MATERIAL AND METHODS: Both digital tomosynthesis (DTS) and cone beam CT (CBCT) reconstruction algorithms are based on backprojection and use cone beam projection data as input. Under limited angle conditions, CBCT is reduced to FDTS, where only a subset of projection data are used for reconstruction. The effect of the reconstruction arc on the spatial resolution, slice thickness, contrast sensitivity, shape distortion and artifacts, was also experimentally studied. The investigation was performed using both simulated and actual fluoroscopic images. RESULTS AND CONCLUSION: Image quality in terms of spatial resolution, slice thickness, shape distortion and artifacts, improved with increasing reconstruction arc and was optimized at 180 degrees, while contrast continued to improve as the arc was increased to 360 degrees. However, DTS was determined to be the technique of choice when reconstruction arcs of less than 40 degrees were used. Consequently, FDTS may be successfully implemented in applications involving extended arc reconstructions, in the range between 40 degrees delimiting the DTS domain and 360 degrees corresponding to CBCT.

Image Processing, Computer-Assisted↗
PubMed1999

Three-dimensional localisation based on projectional and tomographic image correlation: an application for digital tomosynthesis.

Accurate three-dimensional tumor localisation in Radiotherapy, is critical to the treatment outcome, particularly when high dose gradients are present. A number of techniques have been proposed for the localisation of anatomical structures or markers. The present study proposes an approach to a concurrent maximisation of localisation accuracy and efficiency by correlation of tomographic and projectional images. The method introduces an element of direct verification and interactive optimisation of the process. Tomographic images are used for the identification of a point of interest. Its position is computed within the treatment co-ordinate system and verification of this position is achieved by obtaining the beam's eye view of the identified point on two projection radiographs. The key element of the approach is that all images used should be part of one single image data set. The implementation of this localisation method, as part of the functionality of a Digital Tomosynthesis prototype, has provided an integrated facility for localisation, of optimised accuracy and precision, while easy and efficient to use. The considerations are general and apply in principle to any imaging system that can augment tomographic images with projections.

Algorithms↗
PubMedDate not supplied

A wavelet-based method for removal of out-of-plane structures in digital tomosynthesis.

Reconstructed images in digital tomosynthesis (DTS) are affected by artifacts due to blur from planes other than the fulcrum plane. A wavelet-based method has been developed for the discrimination and subsequent removal of unrelated structures from the reconstructed plane. The approach exploits both the specific pattern of noise in DTS and the spatial locality of the wavelet transformation. The technique was implemented on a DTS clinical protoype system. Experimental evaluation on angiographic types of images demonstrated excellent noise differentiation and elimination. The method is therefore particularly useful for certain medical imaging applications such as vascular DTS imaging.

Angiography↗
PubMedDate not supplied

Logarithmic amplifier for computed tomography tasks using fluoroscopic projections.

The image intensifier (II)-based imaging systems, as radiotherapy simulators or C-arm X-ray units, have also been used for image acquisition in computed tomography. When analogue-to-digital conversion is performed on the output signal of the television camera, the accuracy for low-amplitude video signals, corresponding to X-ray pathways crossing high attenuation structures, is limited. To deal with this lack of accuracy, we investigated the benefits of using a logarithmic amplifier (LOGAMP) inserted between the television camera output and the analogue-to-digital converter (ADC) in the image acquisition chain. Such a device was intended to provide better use of the available ADCs of a given resolution and actually to reduce the quantization noise. Simulated data were used in this study, and cases with and without logarithmic amplifier were compared. Based on the simulation results, we formulate requirements for several signal and acquisition system parameters where the use of such a circuit is recommended.

Amplifiers, Electronic↗
PubMedDate not supplied

[Chemical obliterans bronchiolitis after azotic acid exposure].

The authors present the case of a 48 years old man having an exposure to irritant gases (azotic and lactic acids) in a closed space, inhaling them for 5 minutes. Shortly after the accident the patient displayed the signs of corneal and conjunctival burn; several days afterwards respiratory symptoms appeared: shortness of breath, dyspnea to minor efforts, then nocturnal dyspnea and orthopnea. Chest X-ray, CT scan, complex lung function tests and bronchoalveolar lavaje, together with the history of recent exposure to irritant gases led to the diagnosis of hypersensitivity obliterant bronchiolitis. Oral corticoids in dose of 60 mg/day determined a substantial clinical, radiological and functional improvement. The authors make some comments on the need of early diagnosis and efficient treatment.

Anti-Inflammatory Agents↗
PubMedDate not supplied

[Association of atypical pulmonary TB, polyserositis, severe leukopenia and panniculitis. Case report].

Many reports have associated tuberculosis with haematological abnormalities. These reports suggest that severe pulmonary tuberculosis, if associated with reduced tissue cellular reaction, may cause blood discrasias. Anemia was present in 32 percent of patients. Leucopenia with neutropenia and lymphopenia was observed in 15 percent in patients with very severe clinical tuberculosis. Active tuberculosis was associated with significant reductions in absolute numbers of total T, T4 and B lymphocytes, but there were no significant differences in total T8 counts. T4 lymphopenia causes reversal of T4/T8 ratio. Also, many histopathologic diagnosis of panniculitis have been reported in tuberculosis patients--the incidence of panniculitis caused by tuberculosis was 8.2%. We present a case of secondary pulmonary tuberculosis with atypically Rx changes, associated with polyserositis and severe leucopenia, which debuted with a panniculitis.

Adult↗