By Usman Maqsood (Medical Physicist)
Abstract:
Introduction:
Treatment planning of craniospinal irradiation
(CSI) is a challenging task due to its large, irregular treatment
volume and proximity to critical structures known as organs at
risk (OARs). This study is focused on the dosimetric
comparison of treatment plans generated by the two most
commonly employed treatment planning system (TPS) Eclipse
planning system and the Monaco planning system using the
volumetric modulated arc therapy (VMAT) technique. The
objective is to assess the effectiveness and efficiency of
treatment plans generated by two different TPS, incorporating
two distinct algorithms for calculations.
Methods:
Treatment planning was performed on the Eclipse
treatment planning system (version 15.6) employing an
Anisotropic Analytical Algorithm (AAA) and on the Monaco
treatment planning system (version 6.1.2.0) incorporating the
Monte Carlo (MC) algorithm. Treatment plans on both
treatment planning systems were generated by using the auto
feathering technique with no junction shift and multiple arcs.
For comparison of target volumes dosimetric parameters
indices has been chosen such as 1) Homogeneity index 2)
Conformity index and 3) Monitor Units and for doses to OARs
maximum and mean dose has been analyzed.
Results: The result, demonstrated, revealed a slight dosimetric
difference in the obtained dosimetric indices. Both treatment
planning systems showed acceptable target volume coverage of
95% for all treatment plans. Maximum dose to target volumes
or Hot spots is also acceptable for all treatment plans. In this
study, HI values for all treatment plans are acceptable, but
comparatively, Monaco showed a better homogeneity for all
patients’ treatment plans. CI values for all treatment plans for
both systems are satisfactory. However, again comparatively,
Monaco shows better conformity for all treatment plans.
Monitor units are the only indices in this study that show a significant difference in all treatment plans for all six patients.
Eclipse shows much lower MUs (Average 1500) than Monaco
(Average 2600). It is due to the different algorithms that work
behind Eclipse and Monaco. Monaco utilizes the Monte Carlo
(MC) algorithm, which is more complex and advance as
compare to Eclipse which utilize, Anisotropic Analytical
Algorithm (AAA).
Conclusion:
A deep assessment of all six patient treatment
plans demonstrated that both TPS achieved clinically
acceptable results regarding target volume coverage and doses
received by each patient. Assessment of dosimetric indices
revealed slight yet notable differences. Treatment plans
generated in Monaco TPS demonstrated better quality
regarding homogeneity and conformity. Eclipse also shows
satisfactory treatment plan quality, but Monaco exhibits a
marginal edge. A significant difference was observed in
monitor units (MUs), as Monaco demanded considerably
higher MUs than Eclipse. This significant difference is due to
each TPS’s two distinct dose calculation algorithms.