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Module 3 · Lesson 3.1
3.1
Where is AI already used, and what does it do?

AI in Radiology & Medicine

The AI tools that touch Mr. Diaz's scan, how they share the work with radiologists, AI in the rest of medicine, and generative AI in the clinic

Overview

Module 1 explained how AI works. Module 2 explained how radiology works. This module puts them together and asks what AI changes for patients and for you. We start by looking at the AI tools in use today, first in radiology, then across medicine. About 15-20 minutes.

By the end of this lesson you can:

Mr. Diaz's scan, with AI

In Lesson 2.2 you followed Mr. Diaz's CT pulmonary angiogram (CTPA) from the order to the follow-up. Now imagine the same night at a hospital that uses AI. None of these tools replaces a person. Each one does one narrow job at one step.

Step (Lesson 2.2)AI toolWhat it does for Mr. Diaz
1 · OrderDecision supportChecks the order against appropriateness guidelines and suggests CTPA for suspected PE.
3 · ScanImage reconstructionCleans up noise so a lower radiation dose still gives a clear picture.
5 · WorklistPE triageSpots a likely clot within minutes and moves his scan to the top of the radiologist's list.
6 · ReadNodule detectionMarks the 8 mm lung nodule and measures it.
7 · ReportReport draftingSuggests impression wording from the radiologist's findings, and a plain-language version for the patient portal.
9 · Follow-upFollow-up trackerReads the recommendation and reminds the team if the 6-12 month CT is not booked.
Image needed

A radiology worklist (screenshot or mock-up, no patient details) with one CTPA flagged by a PE triage AI and moved to the top.

Image needed

An axial chest CT slice with a nodule-detection AI box and measurement around a small lung nodule.

Most radiology AI does one of four jobs: detect (is something there?), triage (which scans are urgent?), measure (how big, how much?) or draft (put words to it). Each tool on the list was trained and tested separately. A tool that is good at clots knows nothing about nodules.

Who reads first? Four reading designs

At the reading step, the same AI tool can be set up in different ways. What changes is when the radiologist sees the AI output, and who has the last word.

For each card, guess when the radiologist sees the AI's output, then flip it.

ConcurrentAI and radiologist at the same time
ConcurrentAI marks appear while the radiologist reads. Fast, but the marks can pull attention toward what the AI found and away from everything else.
Second readerRadiologist first, AI after
Second readerThe radiologist reads first and reports, then checks the AI output and reconsiders. Slower, but protects independent judgment.
TriageAI decides the order
TriageAI reorders the worklist so likely urgent scans are read sooner. The radiologist still reads every scan. Mr. Diaz's PE tool works this way.
AutonomousAI alone
AutonomousAI makes the call with no human read, for example clearing some clearly normal studies. Rare in radiology so far, and only for narrow tasks.

Think about it

The triage tool misses Mr. Diaz's clot. His scan stays in the normal queue. Does he still get a correct diagnosis? (Yes, but later: a radiologist still reads it. A miss by a triage tool costs time, not the diagnosis.)

AI across medicine

Radiology has the most AI tools of any specialty, but it is not the only one. The ideas from Module 1 apply everywhere: a model learned from examples, it has a sensitivity and specificity, and it can fail on patients unlike the ones it learned from.

Explore: AI beyond radiology
1

Images outside radiology

Any specialty that looks at pictures

  • Eyes: in 2018 the FDA authorized the first autonomous AI system, which checks retina photos for diabetic eye disease in primary care clinics with no eye doctor reading them.
  • Pathology: microscope slides are scanned into digital images, and AI flags areas that look like cancer, for example on prostate biopsies.
  • Skin: tools classify photos of moles and rashes. Many were trained mostly on light skin and work less well on darker skin.
  • Colonoscopy: AI marks possible polyps on the live video during the procedure.
2

Heart signals

ECGs and wearables

  • 12-lead ECG: models can spot a weak heart pump (low ejection fraction) from an ordinary ECG, something cardiologists cannot see by eye.
  • Smartwatches: detect an irregular rhythm that may be atrial fibrillation and tell the wearer to see a doctor. Many alerts are false alarms in young, healthy users (recall PPV from Lesson 1.4).
3

Predictions from the health record

Numbers in, risk scores out

  • Sepsis alerts: scan vital signs and lab results and warn that a patient may be developing sepsis. When one widely used sepsis model was tested at an outside hospital, it missed about two thirds of sepsis cases and raised many false alarms (Wong et al., 2021). Lesson 3.2 returns to this.
  • Deterioration and readmission: scores that predict which ward patients may need intensive care, or who may come back after discharge.
4

Language tools

Generative AI and large language models

  • Ambient scribes: listen to a clinic visit (with the patient's consent) and draft the note. Now common in many health systems.
  • Message drafting: suggest replies to patient portal messages for a clinician to edit.
  • Report drafting: suggest radiology impressions, or rewrite reports in plain language.
  • Chatbots and evidence tools: answer clinical questions. Many students already use them to study.

Generative AI in the clinic

Most of the tools above are narrow: one task, one kind of input, one kind of answer. Generative AI is different. A large language model (LLM) learned from huge amounts of text to predict the next word (Lesson 1.1), and it can write almost anything: a note, a summary, a letter, an answer to a question.

That makes it useful and risky at the same time:

Interactive: find the errors

An LLM wrote this plain-language summary of Mr. Diaz's CTPA report (Lesson 2.4) for the patient portal. Three of its six sentences are wrong. Click each sentence to check it against the real report: PE in the right lower lobe, no strain on the heart, 8 mm nodule, follow-up CT in 6-12 months.

Your CT scan showed a small blood clot in a blood vessel in your right lung.
The clot is putting strain on the right side of your heart.
The scan also found a small spot, about 8 mm across, in the upper part of your right lung.
This spot is an old scar and does not need any follow-up.
Your care team will talk with you about blood thinners to treat the clot.
This plan follows the 2024 American Thoracic Society guideline on small clots (Harmon et al., 2024).

Click a sentence

Decide in your head whether it matches the report before you click.

Four rules for using generative AI:

  1. Never paste anything that could identify a patient into a public chatbot. Use only tools your school or hospital has approved.
  2. Check every fact against the source: the chart, the report, the guideline. Look up every reference.
  3. You own what you submit or sign, whoever drafted it.
  4. Think first, then ask. Lesson 3.3 explains why the order matters.

Which tools are out there?

In the United States, AI that diagnoses or guides treatment is regulated as a medical device by the Food and Drug Administration (FDA). The FDA keeps a public list of AI-enabled devices. By mid-2026 it held more than 1,600 devices, and about three in four were for radiology.

The AI2Practice AI Tool Tracker summarizes that list: how many tools there are, which specialties and tasks they cover, and how the numbers have grown each year. Most are narrow tools like the ones in Mr. Diaz's table. Note what the list does not tell you: whether a tool helps patients, or whether it works at your hospital. That is the topic of Lesson 3.2.

Open the AI Tool Tracker →

Try it (3 minutes)

Open the tracker and find the specialty with the second-most tools. Then pick one radiology task, such as stroke or mammography, and guess how many authorized tools do it.

Knowledge check

Answer each question to continue. Any answer is fine; read the explanation.

A PE tool moves likely urgent scans to the top of the worklist, and the radiologist still reads every scan. Which reading design is this?

Triage changes the order of reading, not who reads. If it misses a clot, the scan is read later rather than never.

An LLM summary of a report includes a reference with authors and a year. What should you do?

LLMs can invent references that look real. They can still be useful drafts, as long as you check facts and citations against the source.

Which of these is safe to paste into a free public chatbot?

A general question with no patient details is fine (and you should still check the answer). Reports, names, dates and screenshots are protected health information and only go into approved tools.

Key takeaways

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← Reading a Radiology Report Next: Does It Work, and Is It Worth It? →