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Evaluation of delivered dose changes during radiation therapy
1Department of Radiotherapy, Centre of Oncology, M.S. Curie Memorial Institute, Gliwice, Poland.
Acta Oncologica (Stockholm, Sweden)
|May 5, 1999
Summary
Changes in tissue thickness during radiotherapy can lead to inaccurate radiation doses. In vivo dosimetry helps detect these errors, highlighting the need to monitor irradiated volume during treatment for head and neck cancers.
Area of Science:
- Radiation oncology
- Medical physics
- Cancer treatment
Background:
- Radiotherapy aims to deliver precise radiation doses.
- Changes in patient anatomy, such as tissue thickness, can alter dose delivery accuracy.
- In vivo dosimetry is crucial for verifying planned doses during treatment.
Purpose of the Study:
- To assess the impact of changes in irradiated tissue thickness on radiotherapy dose delivery errors.
- To evaluate the effectiveness of in vivo dosimetry in detecting these errors.
- To determine the necessity of monitoring irradiated volume dimensions during treatment.
Main Methods:
- In vivo dosimetry was performed on 55 head and neck cancer patients.
- Entrance and exit doses, and irradiated volume sizes were measured during the first and twentieth fractions.
- Real and hypothetical midline doses were calculated to assess dosimetric errors.
Main Results:
- The average irradiated volume size decreased after 20 fractions.
- A statistically significant increase in mean midline dose error (overdosage) was observed by the twentieth fraction compared to the first.
- In vivo dosimetry successfully identified dose delivery errors caused by volume changes.
Conclusions:
- In vivo dosimetry is a valuable tool for detecting radiotherapy dose errors resulting from changes in irradiated volume dimensions.
- Regular monitoring of irradiated volume thickness during radiotherapy is essential for ensuring accurate dose delivery.