Prog Med Phys.  2023 Dec;34(4):41-47. 10.14316/pmp.2023.34.4.41.

Dosimetric Comparison of Three-Dimensional Conformal, Intensity-Modulated Radiotherapy, Volumetric Modulated Arc Therapy, and Dynamic Conformal Arc Therapy Techniques in Prophylactic Cranial Irradiation

• Durmuş IF
• Esitmez D
• Arslan GI
• Okumus A

• KMID: 2550124
• DOI: http://doi.org/10.14316/pmp.2023.34.4.41

Abstract

Purpose
This study aimed to dosimetrically compare the technique of three-dimensional conformal radiotherapy (3D CRT), which is a traditional prophylactic cranial irradiation method, and the intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques used in the last few decades with the dynamic conformal arc therapy (DCAT) technique.
Methods
The 3D CRT, VMAT, IMRT, and DCAT plans were prepared with 25 Gy in 10 fractions in a Monaco planning system. The target volume and the critical organ doses were compared. A comparison of the body V₂, V₅, and V₁₀ doses, monitor unit (MU), and beam on-time values was also performed.
Results
In planned target volume of the brain (PTVBrain), the highest D99 dose value (P<0.001) and the most homogeneous (P =0.049) dose distribution according to the heterogeneity index were obtained using the VMAT technique. In contrast, the lowest values were obtained using the 3D CRT technique in the body V₂, V₅, and V₁₀ doses. The MU values were the lowest when DCAT (P =0.001) was used. These values were 0.34% (P =0.256) lower with the 3D CRT technique, 66% (P =0.001) lower with IMRT, and 72% (P =0.001) lower with VMAT. The beam on-time values were the lowest with the 3D CRT planning (P<0.001), 3.8% (P =0.008) lower than DCAT, 65% (P =0.001) lower than VMAT planning, and 76% (P =0.001) lower than IMRT planning.
Conclusions
Without sacrificing the homogeneous dose distribution and the critical organ doses in IMRTs, three to four times less treatment time, less low-dose volume, less leakage radiation, and less radiation scattering could be achieved when the DCAT technique is used similar to conventional methods. In short, DCAT, which is applicable in small target volumes, can also be successfully planned in large target volumes, such as the whole-brain.

Keyword

Dynamic conformal arc therapy; Volumetric modulated arc therapy; Dynamic conformal arc therapy in whole brain irradiation; Intensity-modulated radiotherapy

Figure

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  Fig. 1 Field aperture and multileaf collimator (MLC) blocking representation from 14 different projections in the dynamic conformal arc therapy (DCAT) technique.

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  Fig. 2 V2, V5, and V10 dose values of the body according to the four different planning techniques. 3D CRT, three-dimensional conformal radiotherapy; IMRT, intensity-modulated radiotherapy; VMAT, volumetric modulated arc therapy; DCAT, dynamic conformal arc therapy.

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  Fig. 3 Monitor unit (MU) (a) and beam-on-time (b) values according to the four different planning techniques. 3D CRT, three-dimensional conformal radiotherapy; IMRT, intensity-modulated radiotherapy; VMAT, volumetric modulated arc therapy; DCAT, dynamic conformal arc therapy.

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  Fig. 4 Display of the dose distributions in volumetric modulated arc therapy (VMAT), dynamic conformal arc therapy (DCAT), three-dimensional conformal radiotherapy (3D CRT), and intensity-modulated radiotherapy (IMRT) planning: while the prescription dose is shown with a light blue isodose line, the maximum dose points of 2,770 and 2,850 cGy are shown with red isodose lines.

Reference

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