قناة الأشعة التعليمـية☢️

https://youtu.be/VnpqylFYtqI?si=3-D4XG7A1XB5wlWR

3. CT Scanner Components
Internal Structure of CT Scanner
Main Parts:
X-ray Tube → produces X-rays
Detectors → capture attenuated beams
Gantry → rotating ring
Patient Table → moves through scanner
Computer System → reconstructs images
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The tube and detectors rotate 360° around the patient.
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4. Image Acquisition Process
X-ray Rotation and Data Collection
Steps:
X-ray tube emits fan-shaped beam
Beam passes through patient
Detectors collect data from multiple angles
One full rotation = one slice
Typically ~1000 projections per rotation
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5. Helical (Spiral) CT
Helical CT Motion
Concept:
Continuous rotation + table movement
Produces spiral data path
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Definition:
Patient moves while tube rotates continuously
Advantages:
Faster scanning
Better 3D imaging
Fewer motion artifacts
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6. Image Reconstruction
Two main methods:
1. Filtered Back Projection (FBP)
Traditional method
Fast but noisy
2. Iterative Reconstruction (IR)
Modern method
Reduces noise and radiation dose
More accurate physics modeling
8. Radiation Dose in CT
CT has higher dose than X-ray because:
Multiple projections
Continuous exposure
Dose Reduction Techniques:
Automatic Exposure Control (AEC)
Iterative reconstruction
Tube current modulation
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9. CT Artifacts
Common Artifacts:
Beam hardening
Motion artifacts
Metal artifacts
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Cause: physics limitations or patient movement
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10. Advanced CT Technologies
Dual-Energy CT (DECT)
Uses two energy levels
Improves tissue differentiation
Photon Counting CT
New technology
Higher resolution + lower noise
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11. Clinical Applications
Trauma imaging
Brain CT
Oncology staging
Cardiovascular imaging
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References
Bushberg JT. The Essential Physics of Medical Imaging, 2012
Hsieh J. Computed Tomography: Principles, 2009
Seeram E. Computed Tomography, 2015
Imaginis CT Education Resource
Helical CT principles (PMC article)

Computed Tomography (CT) Physics – Detailed Version
1. Introduction
Computed Tomography (CT) is an advanced imaging modality that uses X-ray attenuation and computer reconstruction to produce cross-sectional images of the human body.
Unlike conventional X-ray, CT produces 3D volumetric data, improving diagnostic accuracy.
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2. Basic Principle of CT
CT is based on X-ray attenuation:
X-rays pass through the body
Different tissues absorb radiation differently
Detectors measure transmitted intensity
Computer reconstructs the image
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Key idea:
Image = mathematical reconstruction of attenuation data

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