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Verification of lung dose in an anthropomorphic phantom calculated by the collapsed cone convolution method
M J Butson1, R Elferink, T Cheung
1Illawarra Cancer Care Centre, Department of Medical Physics, Wollongong, NSW, Australia. mbutson@usa.net
Physics in Medicine and Biology
|December 1, 2000
Summary
This study validates lung dose calculations using a collapsed cone convolution method in an anthropomorphic phantom. Results confirm the method
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Dosimetry
Background:
- Accurate lung dose calculation is critical for effective radiotherapy.
- Density variations and positioning complexities challenge lung dosimetry.
- The collapsed cone convolution (CCC) method is widely used for dose calculation.
Purpose of the Study:
- To verify the accuracy of the CCC method for calculating lung dose.
- To assess dose variations within phantom slices due to material composition.
- To validate calculated doses using experimental dosimetry.
Main Methods:
- Calculated lung dose using the CCC method on an ADAC Pinnacle 3D planning system for 6 MV and 10 MV beams.
- Utilized an anthropomorphic phantom with varying density slices.
- Measured dose using lithium fluoride thermoluminescent dosimeters (TLDs) and X-Omat V film.
Main Results:
- Calculated doses showed up to 5% variation across phantom slices due to composition.
- Experimental dosimetry (TLDs and film) closely agreed with calculated doses at physical positions.
- The CCC method demonstrated accurate dose calculation in inhomogeneous lung regions.
Conclusions:
- The CCC method accurately calculates lung dose in inhomogeneous regions for 6 MV and 10 MV photon beams.
- Experimental validation supports the reliability of CCC for radiotherapy planning.
- Understanding dose variations within phantom slices is important for accurate dosimetry.