1) Quantum Mottle:
- Also called "photon noise" or "quantum noise."
- It is an inherent characteristic of X-ray imaging and arises due to the statistical nature of X-ray interactions with matter.
- Quantum noise results from the discrete nature of X-ray photons and their quantum interactions within the detector.
- It manifests as random variations in the number of detected photons, leading to fluctuations in image brightness or density.
- Quantum noise is more pronounced at lower radiation doses, where the number of detected photons is limited.
2) Electronic Noise:
- Electronic noise originates from various electronic components within the imaging system, such as the X-ray tube, cables, and image detectors.
- It includes fluctuations in voltage, current, or other electrical signals that can interfere with the accurate capture and processing of X-ray data.
- Electronic noise can manifest as random variations in pixel values or as fixed patterns in the image.
3) Scatter Radiation:
- Scatter radiation occurs when X-rays interact with tissues or objects and are deflected or scattered in various directions.
- Scattered photons can reach the detector and contribute to the overall image formation, leading to a decrease in image contrast and increased background noise.
- Scatter radiation noise can be reduced by using collimators, grids, or scatter-reduction techniques during imaging.
4) Improper Exposure Settings:
- Radiographic noise can also result from incorrect exposure settings, such as inappropriately high or low kVp (kilovoltage peak) or inappropriate mAs (milliampere seconds).
- Incorrect exposure can lead to excessive quantum noise or underexposure, resulting in noisy or poorly contrasted images.
5) Artifacts and Technical Issues:
- Various artifacts or technical issues, such as motion blur, patient movement, electrical interference, or faulty equipment, can introduce noise and distortions in radiographic images.
6) Film Grain Noise:
- In conventional radiography using film-based systems, film grain noise refers to the inherent granularity of the film emulsion.
- It is caused by the discrete nature of silver halide crystals within the film and can contribute to image noise and decreased image quality.
7) Digital Noise:
- In digital radiography, noise can arise during the acquisition, processing, or transmission of digital images.
- It can be introduced by factors such as electronic noise in detectors, data compression algorithms, or image processing techniques.
Radiographic noise can impact image quality and diagnostic accuracy. Various strategies are employed to minimize noise and optimize image quality, such as using appropriate radiation dose, employing noise-reduction algorithms, and implementing quality control measures throughout the imaging process.