RIS vs PACS, in short
The short answer
The RIS runs the radiology workflow and the business: who is booked for which exam, where each exam stands, where the report goes and what gets billed. The PACS runs the images: it receives them from the scanners, stores them and shows them to the radiologist. The RIS tells the scanner what to do; the PACS keeps what the scanner produced.
RIS: the radiology information system
- Receives orders from the EHR
- Schedules patients, rooms and scanners
- Tracks each exam from order to signed report
- Sends the worklist to the scanner
- Distributes results and supports billing
PACS: the picture archiving and communication system
- Receives images from the scanners
- Stores current studies and priors
- Displays images on reading workstations
- Fetches priors for comparison
- Shares images with other sites and readers
What is a radiology information system (RIS)?
A RIS is the departmental system for radiology’s orders and workflow. A paper in Cureus (2022) summarises it: “The RIS contains scheduling information, tracking, result notification, and billing information.” In practice that covers:
- Orders: exam requests arrive from the EHR, are checked and turned into scheduled procedures
- Scheduling: patients, rooms, scanners and staff, including protocols and preparation instructions
- Tracking: where each exam stands, from arrived and scanned to read and signed
- Modality worklist: the scheduled exam is sent to the scanner so details aren’t typed twice
- Results: the signed report goes back to the ordering clinician and the EHR
- Billing: procedure codes and charges captured for the exam and the professional read
- Reporting data: volumes, turnaround times and productivity for the department
What is PACS?
PACS stands for picture archiving and communication system. It receives images from CT, MRI, ultrasound, X-ray and other modalities in the DICOM format, stores them, moves them across the network and displays them in the radiologist’s viewer. The full explainer is in what is PACS.
How RIS, PACS and the EHR work together
- 01
Order
A clinician orders the exam in the EHR; the order reaches the RIS as an HL7 message.
- 02
Schedule and worklist
The RIS schedules the exam and sends it to the scanner through the DICOM Modality Worklist.
- 03
Images
The scanner sends the images to the PACS using DICOM, matched to the order’s accession number.
- 04
Read
The radiologist reads the study from the PACS viewer and dictates in the reporting system.
- 05
Report and bill
The signed report goes to the RIS and EHR as an HL7 message, and the RIS records the completed exam for billing.
This order-to-report sequence is described in Cureus (2022): the order is placed in the EMR, “the RIS then sends the order information to the appropriate modality via the DICOM Modality Work List,” and “the reporting software sends the report to the RIS and EMR via HL7 transactions.” The IHE Scheduled Workflow profile sets out the same flow, “from registration through ordering, scheduling, imaging acquisition, storage and viewing,” so systems from different vendors stay consistent. See DICOM and HL7 in radiology for the messages involved.
RIS vs PACS vs EHR, side by side
| RIS | PACS | EHR / EMR | |
|---|---|---|---|
| Main job | Radiology workflow and business | Images | The whole patient record |
| Holds | Orders, schedules, exam status, reports, charges | DICOM images, priors, image metadata | Orders, results, notes, medications, history |
| Main users | Schedulers, technologists, front desk, billing, radiologists | Radiologists, technologists, clinicians viewing images | Every clinician |
| Standard used most | HL7 (orders, results) and DICOM worklist | DICOM (images), HL7 to RIS and EHR | HL7 and FHIR |
| When it fails | Orders and schedules stall; scanners lose their worklist | Images can’t be stored or read | Ordering and results stop hospital-wide |
Combined RIS/PACS, or separate?
Some vendors sell a single RIS/PACS platform; many hospitals instead use the radiology module of their EHR as the RIS and buy the PACS separately. A combined platform means one vendor and fewer interfaces. Separate systems let you choose the best fit for each job, at the cost of more HL7 interfaces to build and maintain. Either way, ask about downtime: what happens to scheduling and reading when one of them is down. Our PACS vendors comparison notes which vendors describe combined RIS/PACS products, and the radiology director’s checklist covers downtime planning.
Where teleradiology fits
A teleradiology group plugs into the same flow: it needs the order, the images and a way to send the report back. Orders and reports travel as HL7 messages between the hospital and the reading group; images travel as DICOM to the group’s PACS. Exam status in the RIS then shows the read as complete when the signed report arrives.
Orders come to us by HL7 and images by secure routing to our PACS. Signed reports go back into your system. We read on our PACS, so there is nothing for your staff to install or run. We sign a HIPAA Business Associate Agreement (BAA) with every hospital, and our technology runs on SOC 2-compliant platforms. Every TeleRads report is a signed final; we read finals only, never preliminaries.
Questions
What is the difference between RIS and PACS?
The RIS manages radiology workflow and business: orders, scheduling, tracking, results and billing. The PACS manages the images: receiving them from scanners, storing them and displaying them for the radiologist. They exchange information so images match the right order and report.
What does a radiology information system do?
A RIS receives imaging orders, schedules patients and equipment, sends the worklist to the scanners, tracks each exam to the signed report, distributes results and supports billing. It also supplies data on volumes and turnaround.
Is RIS part of the EHR?
Sometimes. Many hospitals use the radiology module of their EHR as the RIS; others run a separate RIS. Either way, it connects to the PACS and exchanges orders and reports by HL7.
What is a RIS/PACS?
A single platform from one vendor that combines the radiology information system and the PACS. It reduces interfaces between the two, but the hospital still needs connections to its EHR.
How do RIS and PACS communicate?
Through standards. Orders and reports move as HL7 messages; the scanner receives its worklist and sends images using DICOM. The IHE Scheduled Workflow profile describes how vendors keep the systems consistent.
Does teleradiology need access to the RIS?
A teleradiology group needs the order, the images and a route for the report. With TeleRads, orders come to us by HL7 and images by secure routing to our PACS, and signed reports go back into your system.