In Vivo Dosimetry Techniques in Radiotherapy

In vivo dosimetry encompasses a suite of techniques designed to measure the radiation dose delivered to a patient during treatment, ensuring accuracy and patient safety. Core methods include thermoluminescent dosimeters (TLDs) and optically stimulated luminescent dosimeters (OSLDs), which record dose information in small passive detectors, as well as semiconductor diodes and metal–oxide–semiconductor field‐effect transistors (MOSFETs) for real-time point measurements. Electronic portal imaging devices (EPIDs) have gained prominence by capturing exit-beam images that can be converted into planar or three-dimensional dose reconstructions. These tools are applied across external beam radiotherapy, volumetric-modulated arc therapy (VMAT) and brachytherapy, offering complementary strengths in spatial resolution, sensitivity and temporal response. In vivo dosimetry plays a vital role in treatment validation, quality assurance and early detection of machine or patient setup errors. Recent advances focus on automating data analysis, integrating dosimetric feedback into adaptive workflows and exploiting artificial intelligence to refine dose reconstruction and predict deviations. Together, these developments reinforce the global drive towards personalised, fault-tolerant radiotherapy and continuous improvement of clinical outcomes.

Research from Nature Portfolio

Recent work has introduced an automated registration algorithm for EPID images that relies on precise bone‐edge detection. By fitting contours of skeletal structures in portal images to digitally reconstructed radiographs, the method reduces translational errors by up to 49 per cent and rotational misalignments by over 40 per cent compared with traditional manual alignment. The approach also accelerates the registration process by more than ten per cent, enhancing both accuracy and efficiency in patient positioning verification and in vivo dose assessment.

In Vivo Dosimetry Techniques in Radiotherapy publication trend

The graph below shows the total number of articles in in vivo dosimetry techniques in radiotherapy across all publications each year (not limited to Nature Index journals).

Technical terms

Electronic Portal Imaging Device (EPID): A detector mounted on the treatment head that captures exit radiation images for dose reconstruction and verification.

Thermoluminescent Dosimeter (TLD): A passive detector that records absorbed dose by emitting light when heated.

Optically Stimulated Luminescent Dosimeter (OSLD): A device that stores energy from ionising radiation and releases it as light upon optical stimulation.

Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET): A semiconductor sensor providing real-time point dose measurements during treatment.

Megavoltage Computed Tomography (MVCT): Three-dimensional imaging acquired with the treatment beam to verify patient alignment and dose distribution.

Gamma Index Analysis: A quantitative comparison of measured and planned dose distributions, combining dose difference and spatial tolerance criteria.

References

1. In Vivo Dosimetry in Radiotherapy: Techniques, Applications, and Future Directions. Encyclopedia (2025).
2. A new registration algorithm of electronic portal imaging devices images based on the automatic detection of bone edges during radiotherapy. Scientific Reports (2020).
3. In silico study of the electronic portal imaging devices sensitivity to parotid glands shrinkage during radiotherapy for nasopharyngeal cases. Journal of Umm Al-Qura University for Applied Sciences (2024).
4. A Novel Approach for Position Verification and Dose Calculation through Local MVCT Reconstruction. Diagnostics (2024).