# In vivo dosimetry and patient-specific quality assurance

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

## TL;DR

Measuring the dose the patient actually receives, with detectors on the skin or the imaging panel behind them, to catch errors before they cause harm.

## Summary

Radiotherapy accidents, though rare, have come from wrong plans, wrong patients and machine faults. Patient-specific quality assurance checks each complex plan on a phantom before the first treatment, and in vivo dosimetry measures the dose during treatment with diodes, thermoluminescent detectors or, increasingly, the electronic portal imaging device behind the patient, which reconstructs the delivered dose in three dimensions. Several countries require in vivo dosimetry by regulation; it is also central to safe FLASH and ultra-high-dose-rate research.

## Fields

- Kind: Technology
- Status: established
- Last checked: 2026-09-17
- Tags: radiation-wave1
- Principle: Independent measurement of the delivered dose, compared with the planned dose, detects errors in planning, setup or machine output.
- Since: 1990
- Strengths: Catches gross errors; Documents the dose actually given; Portal dosimetry needs no extra hardware
- Limitations: Adds workload; Tolerance thresholds are debated; Cannot detect all error types

## Sources

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

## Connected records

- bottlenecks: [Dosimetry standardisation for radioligand therapy](https://nuclide.cc/bottlenecks/b-dosimetry-standardisation/)
- fronts: [Dosimetry](https://nuclide.cc/fronts/f-dosimetry/)
- ideas: [AI segmentation to make voxel-level radioligand dosimetry practical at scale](https://nuclide.cc/ideas/idea-ai-lesion-segmentation-dosimetry/)
- people: [Dale L. Bailey](https://nuclide.cc/people/dale-bailey/)
- roadmaps: [Dosimetry roadmap: MIRD schema → fixed dosing → personalised, image-based dose](https://nuclide.cc/roadmaps/dosimetry-roadmap/)
- terms: [Absorbed dose and the gray (Gy)](https://nuclide.cc/terms/absorbed-dose-term/), [Effective half-life](https://nuclide.cc/terms/effective-half-life/), [Equivalent dose and effective dose (sievert)](https://nuclide.cc/terms/equivalent-dose/), [MIRD formalism](https://nuclide.cc/terms/mird-formalism/), [Radiopharmaceutical extravasation](https://nuclide.cc/terms/extravasation-radiopharmaceutical/), [Time-activity curve (TAC)](https://nuclide.cc/terms/time-activity-curve/)

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