Calculating Weighting Factors for Mixing Megavoltage Photon Beams to Achieve Desirable Dose Distribution in Radiotherapy
Background: In radiotherapy, low-energy photon beams are better adapted to the treated volume, and the use of high-energy beams can reduce hot spots in the radiation therapy. Therefore, mixing low and high energies with different ratios can control the rate of hotspots, as well as the dose distri...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Shiraz University of Medical Sciences
2019-06-01
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| Series: | Journal of Biomedical Physics and Engineering |
| Subjects: | |
| Online Access: | http://jbpe.ir/Journal_OJS/JBPE/index.php/jbpe/article/view/789/513 |
| Summary: | Background: In radiotherapy, low-energy photon beams are better adapted to
the treated volume, and the use of high-energy beams can reduce hot spots in the
radiation therapy. Therefore, mixing low and high energies with different ratios can
control the rate of hotspots, as well as the dose distribution of the target volume.
Material and Methods: The percentage depth doses (PDDs) were calculated
at various depths, by using a fitted double exponential equation. Then, using quality
factor equation and PDD of a 10×10 cm2
field, the amount of energy equivalent to
each PDD and the value of weighting factors of 6, 18 MV energies were calculated to
produce different energies. To validate the mathematical model, dosimetry of 10 MV
energy was used. For this purpose, PDDs and dose Profile of 10 MV obtained from
the mix were compared with ones obtained from the measurement
Results: The value of weighting factor of 6 MV energy required for the 10 ×10
cm2
field to create dose distribution of 15 MV energy using 6 and 18 MV energies
was obtained as equal to 0.57. Comparison of percentage depth dose curves and dose
profile shows good agreement with the practical measurements of 10 MV for 10×10
cm2
field using gamma index.
Conclusion: The simultaneous use of high and low photon energies with different weighting factors to achieve desirable energy makes possible the treatment of
tumors located at various depths without the need for different modes of energy in
the accelerator leading to a decrease in the cost of the equipment and a safer treatment of the cancerous patients.
Citation: Tahmasebi Birgani M. J, Chegeni N, Tahmasbi M, Hazbavi M, Hoseini S. M. Calculating Weighting Factors for Mixing Megavolt- age Photon Beams to Achieve Desirable Dose Distribution in Radiotherapy. J Biomed Phys Eng. 2019;9(3):279-284. https://doi.org/10.31661/
jbpe.v0i0.789. |
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| ISSN: | 2251-7200 2251-7200 |