Tag Archives: distortion

MRI Phantom
4
Feb

Overview

MRI phantoms provide stable reference signals for assessing SNR uniformity and geometric accuracy. They are used for routine QA and research validation. Phantoms support quantitative mapping and sequence comparison.

Relaxation Properties

Phantoms contain materials with known T1 and T2 relaxation times for calibration. Temperature control ensures consistent relaxation properties during testing. Multi compartment phantoms enable multiparametric assessment.

Geometric and Distortion Testing

Phantoms with grid patterns detect geometric distortion and gradient non linearity. Distortion correction and shimming procedures are validated using phantom data. Regular testing ensures accurate spatial measurements.

Long Term Stability

Phantom stability over time is critical for longitudinal studies and multicenter trials. Documentation of phantom performance supports reproducibility and regulatory submissions. Proper storage and handling preserve phantom integrity.

Image Intensifier
4
Feb

Overview

Image intensifiers convert x rays to visible light and amplify the signal for fluoroscopic display. They were common in older C arm and fluoroscopy systems. Image intensifiers are being replaced by flat panel detectors in modern equipment.

Advantages and Limitations

Image intensifiers provide real time imaging with good temporal resolution. They can suffer from geometric distortion and vignetting compared with flat panels. Maintenance includes vacuum integrity and alignment checks.

Care and Calibration

Regular calibration ensures uniform brightness and minimal distortion. Replacement of worn components restores image quality. QA protocols monitor performance over time.

Clinical Use

Image intensifiers remain in use in some legacy systems and resource constrained settings. Understanding their limitations informs interpretation and procedural planning. Upgrades to flat panel detectors improve image quality and dose efficiency.