Fix dollar signs + add descendants section

# [TECH] Medical Imaging (X-ray, CT, PET)

**Medical Imaging** encompasses X-ray, computed tomography (CT), positron emission tomography (PET), and ultrasound — technologies that allow non-invasive visualisation of the body's interior.

## Overview

Röntgen discovered X-rays (1895); within a year they were in clinical use. Hounsfield and Cormack developed CT scanning (1972), using X-rays from multiple angles and computed reconstruction to produce 3D images. PET scanning uses radiotracers to image metabolic activity, crucial for oncology. CT and PET together revolutionised cancer detection, trauma assessment, and cardiac imaging. AI-assisted reading of medical images (2010s) is now deployed clinically for detecting diabetic retinopathy, lung cancer, and COVID-19.

## Key Actors

- **Companies**: GE Healthcare, Siemens Healthineers, Philips, Toshiba Medical, Canon, Varian
- **Inventors**: Wilhelm Röntgen (1845–1923, **Nobel Prize 1901**), Godfrey Hounsfield (1919–2004) & Allan Cormack (1924–1998, **Nobel Prize 1979**)

## Key Patents

- Hounsfield, G. UK Patent 1,283,915 (1972) — CT scanner

## Economic Value

Global diagnostic imaging market: **\$40 billion/year** (2023, Grand View Research). Including contrast agents, AI software: \$55B+/year. Healthcare value (prevented misdiagnosis, improved outcomes): \$300B+/year globally.

## Notes

Grand View Research *Medical Imaging Market* 2023. WHO estimates that diagnostic imaging informs ~70% of clinical decisions.

## What This Enables
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- **[TECH] AI & Large Language Models** — Large annotated imaging datasets (CheXpert, MIMIC-CXR, TCGA) trained the first clinically deployed deep learning models.
- **[SCI] Deep Learning** — Convolutional networks for pathology slides, radiology images, and ophthalmoscopy were among the first successful deep learning applications.
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# Parents

* [SCI] Nuclear Physics
* [SCI] Nuclear Physics
* [TECH] MRI (Magnetic Resonance Imaging)
* [SCI] Genomics & Computational Biology