Filtered Radon Back Projection
Filtered Radon Back Projection - Related Videos
16:44
Born Normalization for Fluorescence Optical Projection Tomography for Whole Heart Imaging
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Cited by 15 •
2009
We suggest a Born normalized approach for Optical Projection Tomography (BnOPT) that accounts for the absorption properties of imaged samples to obtain accurate and quantitative fluorescence tomographic reconstructions. We use the proposed algorithm to reconstruct the fluorescence molecular probe distribution within small animal organs.
01:27
Passive Filters
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2024
Passive filters are utilized to shape the frequency spectrum of signals across a diverse array of applications. These filters, using only passive elements like resistors (R), inductors (L), and capacitors (C), are capable of selectively allowing or blocking certain frequency ranges without the need for external power sources. Low-Pass Filters Low-pass filters are designed to transmit signals with frequencies lower than the cutoff frequency, ωc, and attenuate those above it. The cutoff frequency...
02:18
Fischer Projections
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2023
Learning to draw Fischer projections of molecules and understanding their relevance plays a crucial role in the visual depiction of organic molecules. A Fischer projection is a two-dimensional projection on a planar surface to simplify the three-dimensional wedge–dash representation of molecules. This is especially helpful in the case of molecules with multiple chiral centers that can be difficult to draw. Here, all the bonds of interest are represented as horizontal or vertical lines. While...
09:32
Evaluating the Effect of Coated Filters and Pre-Filters on the Infectivity and Concentration of Aerosolized Phi6 Virus
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2026
Here, we present a study to evaluate the anti-viral efficacy of copper- and silver-based surface coatings on air filters. Using a bioaerosol chamber and Phi6 bacteriophage, this method quantifies viral inactivation and mechanical filtration efficiency for self-sanitizing indoor air technologies.
01:25
Active Filters
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2025
Active filters are electronic circuits that use operational amplifiers (op-amps), resistors, and capacitors to filter out unwanted frequency components from a signal. A first-order low-pass active filter is designed to pass signals with a frequency lower than a certain cutoff frequency and attenuate frequencies higher than that cutoff frequency. The transfer function for a first-order low-pass active filter is: Where Af is the gain at low frequencies also known as the dc gain, s is the...
FAQs
The ramp filter compensates for the way backprojection distributes projection information across the image. By emphasizing high-frequency content in each angular measurement before reconstruction, it preserves fine variation that would otherwise be less prominent. This filtering step is central to producing interpretable cross-sectional structure rather than relying on unprocessed projection values.
Each detector reading samples X-ray attenuation along a different path through the specimen. Combining these angular views supplies complementary information about internal structure, allowing the reconstruction calculation to place measured values along their corresponding paths. The result is a cross-sectional representation that reflects information distributed through the specimen rather than a single viewing direction.
Detector measurements are line integrals of the specimen’s X-ray attenuation, so each value summarizes attenuation along a particular path. During reconstruction, these measurements are filtered and assigned back along those paths. Their combination transforms projection-level attenuation data into spatially organized information that supports analysis of internal biological structure and morphology.
A typical reconstruction workflow begins with detector acquisition at multiple angles. The recorded line integrals are then subjected to the ramp filter, which emphasizes high-frequency information. Finally, the filtered projections are backprojected along their measured paths. This ordered sequence links raw measurements to a two- or three-dimensional representation of the specimen.
In biological research, the method supports imaging and analysis of tissues, organs, biomaterials, and small organisms. Its output can be used to examine internal anatomical structure or biological morphology in two or three dimensions. Micro-computed tomography is a particularly relevant setting because the reconstruction provides the computational foundation for interpreting projection measurements from specimens.
Speed and interpretability make the approach useful for anatomical and morphology-focused investigations. Efficient reconstruction supports practical analysis, while the mathematical steps clarify how measured projections contribute to the resulting image. Researchers can therefore use the method for quantitative studies of biological form, including examinations of tissues, organs, biomaterials, and small organisms.