# CT (computed tomography)

Source: https://nuclide.cc/technologies/ct/  
Nuclide record `ct` (Technology). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

A CT scan is a fast 3D X-ray that shows the size and shape of tumours and whether they have spread.

## Summary

Computed tomography rotates an X-ray source and detector around the body and reconstructs the measured attenuation into cross-sectional images, with iodinated contrast highlighting vasculature. In use since 1971, it is the workhorse of staging and response assessment and the standard measurement tool for RECIST. It is fast, ubiquitous, offers sub-millimetre resolution and is excellent for lung, liver, bone and lymph nodes. Its limits are that it shows anatomy only, so it cannot distinguish scar from live tumour or give biological information, it has limited soft-tissue contrast, it performs poorly for brain, marrow and small peritoneal disease, and it delivers ionising radiation. Photon-counting CT improves resolution at lower dose, while PET/CT and MRI fill the gaps in biology and soft tissue. CT is the quick 3D X-ray that most cancer decisions are measured against.

## Fields

- Kind: Technology
- Status: standard-of-care
- Last checked: 2026-09-04
- Principle: A rotating X-ray source and detector measure attenuation, which is reconstructed into cross-sectional images. Iodinated contrast highlights vasculature.
- Since: 1971
- Strengths: Fast, ubiquitous; Sub-millimetre resolution; Standard for RECIST response
- Limitations: Anatomic only; cannot distinguish scar from live tumour; Radiation dose; Poor for brain, marrow, and small peritoneal disease

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/CT_scan
- Wikipedia: https://en.wikipedia.org/wiki/CT_scan

## Connected records

- companies: [Canon Medical Systems](https://nuclide.cc/companies/canon-medical/), [GE HealthCare](https://nuclide.cc/companies/ge-healthcare/), [Siemens Healthineers](https://nuclide.cc/companies/siemens-healthineers/), [United Imaging](https://nuclide.cc/companies/united-imaging/)
- indications: [Hereditary pheochromocytoma and paraganglioma (SDHx, VHL, RET, NF1, MAX and TMEM127)](https://nuclide.cc/indications/hereditary-ppgl/), [Lung neuroendocrine tumours (typical and atypical carcinoid)](https://nuclide.cc/indications/lung-net/), [Non-small cell lung cancer](https://nuclide.cc/indications/nsclc/), [Small-cell lung cancer](https://nuclide.cc/indications/sclc/)
- technologies: [CT, MRI and PET scanner manufacturing](https://nuclide.cc/technologies/medical-imaging-scanner-manufacturing/), [PET/CT](https://nuclide.cc/technologies/pet-ct/), [Quantitative imaging biomarkers (RECIST, PERCIST, SUV, ADC)](https://nuclide.cc/technologies/quantitative-imaging-biomarkers/), [SPECT/CT](https://nuclide.cc/technologies/spect-ct/)
- institutions: [Erasmus MC Cancer Institute](https://nuclide.cc/institutions/erasmus-mc/)

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