What is teleradiology?
Teleradiology is the electronic transmission of medical images — CT, MRI, X-ray, ultrasound, nuclear medicine — from the site where they are acquired to a radiologist somewhere else, who interprets the study and issues a report. In plain terms: it lets a hospital, emergency department, or outpatient imaging center get a scan read by a qualified radiologist who is not standing in the building.
That single capability solves a stubborn structural mismatch. Imaging equipment is everywhere; radiologists are not. Teleradiology decouples where a scan is taken from where it is read, which is why it now underpins after-hours coverage, subspecialty second opinions, disaster and rural access, and day-to-day reading for facilities that cannot staff a full-time radiologist. The commercial market reflects that dependence: analysts valued the global teleradiology market at roughly USD 15.6 billion in 2024 and project it to reach about USD 60.3 billion by 2030, a compound annual growth rate near 25.7%, with North America the largest region at about 38.5% of the 2024 market, according to Grand View Research.
The demand behind those numbers is not hype. The Association of American Medical Colleges projects a shortage of up to 86,000 physicians by 2036, with radiology among the specialties feeling the squeeze (AAMC). When you cannot hire your way out of a reading backlog, moving the read instead of the radiologist becomes the default answer.
How does teleradiology work? Preliminary vs final reads
The mechanics are consistent across providers. A scan is acquired at what the American College of Radiology calls the transmitting site — the facility with the scanner. The images are securely routed over an encrypted network to a receiving site, where a radiologist pulls the study onto a worklist, reviews it against the clinical history, and returns a report that flows back into the ordering facility's PACS or electronic health record.
The part that confuses people is the difference between two kinds of read. Per the ACR White Paper on Teleradiology Practice, a remote radiologist may provide either:
A preliminary interpretation
A first read — often overnight or STAT — that guides immediate patient management but is later reviewed and finalized by a radiologist at the ordering facility. Most classic after-hours teleradiology is preliminary: it moves the emergency decision forward, and the local radiologist owns the final report the next day.
A final interpretation
The definitive, signed report of record, provided by the teleradiologist where the facility, licensure, and credentialing all permit it. Increasingly common for routine daytime overflow and subspecialty work, this shifts full accountability to the reading radiologist rather than a local one.
The distinction matters operationally because it determines who is accountable for the signature, how the two reports are reconciled, and where discrepancies get caught. It is also the seam where turnaround problems tend to appear — the gap between a fast preliminary and a slow final is a recurring failure mode in outsourced arrangements, as our breakdown of when radiology outsourcing goes wrong illustrates.
Nighthawk radiology: where teleradiology began
Teleradiology is older than most people assume. Its roots trace to mid-20th-century military use and an early MGH–Logan Airport telemedicine link — connecting Massachusetts General Hospital with a medical station at Boston's Logan Airport; it became broadly practical only in the 1990s as high-speed networks and digital image quality caught up, per a history published in Frontiers in Radiology.
The breakthrough that made teleradiology a business was the nighthawk model. Overnight emergency coverage is the hardest, least popular shift to staff. Beginning around the turn of the millennium, companies solved it with geography: they stationed US-licensed, US-board-certified radiologists in overseas time zones — famously starting in Sydney, Australia — so that a scan taken at 3 a.m. in a US emergency department landed on the worklist of a radiologist working a comfortable daytime shift on the other side of the world. Paul Berger, who co-founded NightHawk Radiology, pioneered this distributed-reading model; his role as a NightHawk founder is recounted in an interview with Radiology Business.
Those overseas reads were almost always preliminary, finalized by a US radiologist in the morning — the prelim-vs-final split above, applied at scale. "Nighthawk" has since become shorthand for any after-hours teleradiology coverage, whether the reader is overseas or three states away. The economics of that specific shift — and the surcharges attached to it — are worth understanding on their own; we cover them in our guide to after-hours radiology coverage options.
Credentialing and licensing: the operational backbone
The reason teleradiology is harder to run than it looks is regulatory, not technical. A radiologist reading a study is practicing medicine on a patient located in a specific US state, and that state's rules apply. ACR guidance holds that the physician providing the interpretation should maintain the licensure required at both the transmitting and receiving sites — in practice, a valid medical license in the state where the patient is (ACR White Paper).
That single requirement drives a lot of teleradiology's cost and complexity. A national teleradiology practice may need radiologists licensed across dozens of states, plus hospital-by-hospital credentialing at every facility they read for. The Interstate Medical Licensure Compact now offers an expedited pathway across more than 40 member states and jurisdictions, which speeds the paperwork — but it does not eliminate the underlying obligation to be licensed wherever the patient sits.
Credentialing adds a second layer: teleradiology partners are expected to use radiologists who are board-certified by the American Board of Radiology and to keep license status current at every reading location. This is also where the policy fights are — licensure compacts, CMS supervision rules, and offshore-reading accountability are live issues, as we track in our teleradiology policy watch-list. For any buyer, "who is licensed, where, and who signs" is the first due-diligence question, not the last.
The economics of teleradiology services
Teleradiology services are usually priced per study, with modifiers that reveal where the real costs live: subspecialty reads, STAT turnaround, and after-hours coverage all carry premiums. That pricing structure is a direct consequence of the licensing and staffing burden above — a scarce, multi-state-licensed radiologist reading an urgent overnight CT is an expensive resource, and the per-study rate reflects it.
For an imaging center or hospital, the practical trade-off is coverage certainty versus cost and control. Outsourcing reads buys 24/7 availability without the fixed cost of an in-house radiologist, but it introduces dependence on someone else's turnaround, someone else's worklist priorities, and contract terms that can move. Understanding the full cost stack — in-house, locum, and teleradiology — before signing is essential; we break the numbers down in our comparison of CT radiology coverage costs.
Where AI report drafting fits
The newest layer in the workflow is AI. Rather than competing with teleradiology, report-drafting AI slots into the same seam the prelim/final split already occupies: it produces a structured, comprehensive draft — and triages urgent findings — before a radiologist opens the study, compressing turnaround and helping remote teams absorb rising volume without proportionally growing headcount. The distinction that matters is architectural: narrow detection tools flag one finding at a time, while foundation models aim for one complete draft per study, as explained in foundation models vs narrow AI in radiology.
Critically, this is a draft-then-sign model, not autonomous reading. In the xAID workflow, the AI generates a ready-to-sign report, xAID's in-house radiologist reviews every preliminary, and the final signature stays with the client's own reading radiologist — the accountable human read that teleradiology has always centered on remains exactly where it is. That is why AI drafting is best understood as complementary infrastructure. For a head-to-head on the two approaches, see AI vs teleradiology; teleradiology providers evaluating AI as capacity relief can start with xAID for teleradiology companies.
Frequently asked questions
What is teleradiology?
Teleradiology is the electronic transmission of medical images — CT, MRI, X-ray, ultrasound — from the location where they are acquired to a radiologist in a different location who interprets them and issues a report. It lets a hospital or imaging center get a scan read by a qualified radiologist who is not physically on site, which is why it underpins after-hours coverage, subspecialty second opinions, and remote reading for facilities without a full-time radiologist.
How does teleradiology work?
Images are acquired at the transmitting site, securely routed over an encrypted network, and delivered to a remote radiologist's worklist. The radiologist reviews the study and returns either a preliminary interpretation, which a local radiologist later finalizes, or a final interpretation where the arrangement and licensure allow it. The report flows back into the ordering facility's PACS or EHR. Turnaround, licensing, and credentialing rules govern every step.
What is nighthawk radiology?
Nighthawk radiology refers to after-hours teleradiology coverage — reading emergency studies overnight for facilities whose on-site radiologists are off. The model became widespread in the early 2000s when companies stationed US-licensed, US-board-certified radiologists in overseas time zones, starting in Australia, so overnight US scans could be read during the radiologist's daytime hours. Those reads were typically preliminary, finalized by a US radiologist the next morning.
What licensing does a teleradiologist need?
Under American College of Radiology guidance, the physician who interprets a study transmitted by teleradiology should hold the licensure required at both the transmitting and receiving sites — in practice, a license in the state where the patient is located. Radiologists commonly maintain licenses in many states, and the Interstate Medical Licensure Compact now offers an expedited pathway across more than 40 member jurisdictions, though it does not remove the underlying state-by-state requirement.
Where does AI fit into teleradiology?
AI is increasingly used to draft structured reports and triage urgent findings before a radiologist reads a study, compressing turnaround and helping remote teams handle rising volume. It functions as a first-draft and safety-net layer, not an autonomous reader: the report is delivered ready-to-sign, and the final signature stays with the client's own reading radiologist. This draft-then-sign model complements teleradiology rather than replacing the accountable human read.
Sources: market figures from Grand View Research; physician-shortage projection from the AAMC; teleradiology history from Frontiers in Radiology (DOI 10.3389/fradi.2022.866643); Paul Berger's NightHawk founder role recounted in Radiology Business; licensing and prelim/final definitions from the ACR White Paper on Teleradiology Practice and the Interstate Medical Licensure Compact. Figures are rounded as reported.