The Dosimetric Effects of Different Beam Energy on Physical Dose Distributions in IMRT Based on
Analysis of Physical Indices
42
conduct photon and neutron measurements considering
complication calculation, attempted to address 15-MV
energy IMRT benefits outweighing risk.
Park JM et al. [21] suggested that mixing high- and
low-energy photon beams in an IMRT plan for deep-
seated tumors can improve the overall plan quality. Sung
W et al. [22] compared the effect of three photon ener-
gies (6-MV, 10-MV, and 15-MV) on IMRT plans to treat
twenty prostate cancer patients, 10-MV plans showed
better OAR sparing and less integral doses than the 6-
MV. In agreement with that work this study indicates
that the use of 10 MV photons was dosimetrically com-
parable with 6 MV photons in terms of target coverage,
homogeneity, conformity, and OAR savings. The dose to
the normal tissue surrounding the target volume was found
to be higher for the 6-MV than 10-MV beams, but it
should be taken into consideration that for 6-MV there
are no secondary neutrons, and radiation leakage is rela-
tively low, also room shielding requirements are signifi-
cantly less for 6-MV photons than for 10-MV photons.
5. Conclusion
In conclusion, the use of high-energy 10-MV photon
achieves the same tumour control as the 6-MV photon
with acceptable complication rate as well as better saving
for normal tissue, while generating negligible neutron dose
equivalent. It is recommended that the choice to treat at
10 MV be taken as a risk vs. benefit as the clinical signifi-
cance remains to be determined on case by case basis.
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