Related Experiment Video
Updated: May 7, 2026
07:31
Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator
Published on: May 9, 2014
Small field dosimetric characterization of a new 160-leaf MLC
G Cranmer-Sargison1, P Z Y Liu, S Weston
1Department of Medical Physics, Saskatchewan Cancer Agency, Saskatoon, Canada. Academic Unit of Medical Physics, Faculty of Medicine and Health, University of Leeds, Leeds, UK.
Physics in Medicine and Biology
|October 1, 2013
Summary
The new Agility 160-leaf multi-leaf collimator (MLC) demonstrates superior positional accuracy and reproducibility compared to the older MLCi2. This advanced MLC system offers improved performance for small field radiation therapy applications.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Equipment Characterization
Background:
- Accurate characterization of multi-leaf collimators (MLCs) is crucial for precise radiation delivery in cancer treatment.
- Small field dosimetry presents unique challenges due to detector volume averaging and perturbation effects.
Purpose of the Study:
- To perform a comprehensive 6 MV small field characterization of the Elekta Agility 160-leaf MLC.
- To compare the performance of the Agility MLC with the Elekta MLCi2, focusing on output, profile, and positional accuracy.
- To derive small field detector correction factors for diode dosimeters.
Main Methods:
- Profile and central axis relative output measurements were conducted at 10.0 cm depth for field sizes ranging from 0.5 cm to 1.0 cm.
- Measurements utilized diode detectors and an air-core fiber optic scintillation dosimeter (FOD).
- Positional accuracy and field width constancy were assessed as a function of collimator rotation.
Main Results:
- The Agility 160-leaf MLC exhibited greater positional reproducibility and tighter positional tolerance than the MLCi2.
- Small field correction factors for diodes were approximately 2% greater for MLCi2 compared to the Agility MLC at the smallest field sizes.
- Standard experimental uncertainties for relative output measurements at the smallest field size were approximately 0.5% for Agility and 1.0% for MLCi2.
Conclusions:
- The Agility 160-leaf MLC demonstrates superior performance in small field applications compared to the MLCi2, particularly regarding positional accuracy.
- The findings support the use of the Agility MLC for precise small field radiotherapy, with established correction factors for diode dosimetry.
- Differences in relative output, profile widths, and correction factors highlight the importance of MLC-specific characterization.
