PACS / informatics

PACS / informatics

Exam category: Image Production → Equipment Operation & QA
Why it matters: This is pure "know the acronym and what it actually does" territory — the registry likes to test whether you can tell PACS, RIS, HIS, EMR, and EHR apart.

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The big picture (plain English)

A patient's imaging journey generates two different kinds of digital information: the pictures (the actual images) and the paperwork (schedule, orders, billing, reports, and the patient's broader medical history). Different systems are built to handle each.

1. The core systems

2. DICOM, HL7, and teleradiology

DICOM (Digital Imaging and Communications in Medicine) is the standard format that lets equipment from different manufacturers and different facilities exchange images and speak the same language — without it, one vendor's PACS couldn't reliably read another vendor's images.

HL7 (Health Level Seven) is the other standard in the pair, and the split between the two is the part the registry actually tests. DICOM carries the images; HL7 carries the text and administrative data — demographics, reports, claims, and orders. HL7 is the standard generally used to let the HIS and the RIS talk to each other. So the order you pull off the modality worklist reached the RIS as HL7, while the images you send back travel as DICOM.

Teleradiology — remote transmission and viewing of images — depends entirely on DICOM to work across different systems, and allows interpretation to happen anywhere, even intercontinentally.

3. The basic workflow

Patient registers in the EMR → request goes to RIS (opens a Protocol Worklist / Imaging Modality Worklist) → technologist performs the exam and retrieves the order from the modality worklist → images and results go to PACS/RIS → radiologist interprets remotely or on-site.

4. Downtime procedures

When PACS or the network goes down, the department falls back to manual/paper-based processes for ordering, tracking, and identifying images until systems are restored, then reconciles the paper trail back into the digital system once it's back up.

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Registry must-know facts

• PACS = images only. RIS = schedule/billing/reports, and requires PACS to function.
• EMR is generally facility-specific; EHR is designed to be shared across providers/facilities — that's the core distinction to have cold.
• DICOM is what makes cross-vendor, cross-facility image exchange possible.
• DICOM = images; HL7 = textual and administrative data (demographics, reports, claims, orders), including the HIS↔RIS exchange. If a question asks what HL7 does, the answer is the words, not the pictures.
• Teleradiology depends on DICOM.
• Every department needs a manual fallback plan for when digital systems (PACS/network) are down.

Common trap

Students often assume PACS handles patient scheduling or billing information. It doesn't — that's entirely RIS's job. PACS is images and only images.

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Source: Fauber, Radiographic Imaging and Exposure, 6th ed., Ch. 5 (PACS, RIS/HIS, DICOM — this material moved from Ch. 4 in the 5th ed. to Ch. 5, Digital Image Processing, Display, and Data Management, in the 6th); Bushong, Radiologic Science for Technologists, 12th ed., Ch. 11 (teleradiology); Carter & Vealé, Digital Radiography and PACS, 3rd ed., Ch. 8 (HL7 vs. DICOM, the HIS↔RIS exchange, and the EMR as part of the HIS) and Ch. 11 (the EHR as a record consulted across more than one healthcare organization). (Downtime procedures remain standard departmental practice rather than a cited passage — flagging that rather than overstating the citation.)