phantom
Physical test object with known properties used to verify imaging scanner calibration. Modality-specific:
- CT — water phantom (HU calibration), CTDI phantom (16 cm head / 32 cm body), ACR / Catphan / Mercury for image-quality.
- MRI — ACR phantom (geometric / contrast / SNR), NEMA body phantom for advanced metrics.
- Mammography — ACR / MQSA paraffin phantom for daily / weekly QC.
- Ultrasound — tissue-mimicking phantoms for B-mode resolution / sensitivity.
- Nuclear medicine / PET — flood phantom (uniformity), NEMA IQ phantom (image quality, sensitivity), Jaszczak / Hoffman cardiac.
Why it matters to buyers: Phantom QC is required by ACR accreditation and performed daily (CT, NM), weekly (mammography), or monthly (MRI advanced) per modality.
Why it matters to engineers: Phantom failures are the #1 trigger for service calls at daily QC time — typically the first detected drift before clinical impact. QA binder of phantom records is part of the inspection-ready documentation for every accreditation.