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Clinical experience with routine diode dosimetry for electron beam radiotherapy
R Yaparpalvi1, D P Fontenla, B Vikram
1Department of Radiation Oncology, Montefiore Medical Center, The University Hospital for the Albert Einstein College of Medicine, Bronx, New York 10467, USA. ryaparpa@montefiore.org
International Journal of Radiation Oncology, Biology, Physics
|November 10, 2000
Summary
In vivo diode dosimetry is valuable for electron beam radiotherapy accuracy but can cause dose reduction, especially with small fields and low-energy beams. Careful diode placement is crucial to prevent errors and ensure effective treatment.
Area of Science:
- Medical Physics
- Radiation Oncology
Background:
- Electron beam radiotherapy often lacks formal treatment planning.
- In vivo dosimetry is essential for monitoring treatment delivery accuracy and preventing errors.
Purpose of the Study:
- To present clinical experience with patient dose verification using electron diodes.
- To quantitatively assess dose perturbations caused by diodes during electron beam radiotherapy.
Main Methods:
- Utilized a commercial diode dosimeter for in vivo dose measurements on 360 patients.
- Assessed diode perturbation effects on electron beams (6-20 MeV) using film dosimetry.
- Generated customized patient dosimetry reports for analysis.
Main Results:
- 11.5% of routine diode dosimetry measurements fell outside the acceptable +/-6% dose deviation window.
- Dose discrepancies were primarily due to inaccurate diode orientation and positioning.
- Diode presence caused significant dose reduction (up to 16%) with smaller fields and lower energy beams.
Conclusions:
- Diode dosimetry is convenient and valuable for real-time verification of electron beam radiotherapy dose delivery.
- Frequent diode use is undesirable for small fields and low-energy electrons due to potential target volume dose reduction.