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. 2015 Jan 8;16(1):5199.
doi: 10.1120/jacmp.v16i1.5199.

Validation of fluence-based 3D IMRT dose reconstruction on a heterogeneous anthropomorphic phantom using Monte Carlo simulation

Yuji Nakaguchi  1 , Takeshi Ono, Masato Maruyama, Nozomu Nagasue, Yoshinobu Shimohigashi, Yudai Kai
Affiliations

Validation of fluence-based 3D IMRT dose reconstruction on a heterogeneous anthropomorphic phantom using Monte Carlo simulation

Yuji Nakaguchi et al. J Appl Clin Med Phys. .

Abstract

In this study, we evaluated the performance of a three-dimensional (3D) dose verification system, COMPASS version 3, which has a dedicated beam models and dose calculation engine. It was possible to reconstruct the 3D dose distributions in patient anatomy based on the measured fluence using the MatriXX 2D array. The COMPASS system was compared with Monte Carlo simulation (MC), glass rod dosimeter (GRD), and 3DVH, using an anthropomorphic phantom for intensity-modulated radiation therapy (IMRT) dose verification in clinical neck cases. The GRD measurements agreed with the MC within 5% at most measurement points. In addition, most points for COMPASS and 3DVH also agreed with the MC within 5%. The COMPASS system showed better results than 3DVH for dose profiles due to individual adjustments, such as beam modeling for each linac. Regarding the dose-volume histograms, there were no large differences between MC, analytical anisotropic algorithm (AAA) in Eclipse treatment planning system (TPS), 3DVH, and the COMPASS system. However, AAA underestimated the dose to the clinical target volume and Rt-Parotid slightly. This is because AAA has some problems with dose calculation accuracy. Our results indicated that the COMPASS system offers highly accurate 3D dose calculation for clinical IMRT quality assurance. Also, the COMPASS system will be useful as a commissioning tool in routine clinical practice for TPS.

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Figures

Figure 1
Figure 1
The MatriXX detector mounted on the gantry of a linear accelerator.
Figure 2
Figure 2
RANDO Alderson phantom (a) and contouring of target and OAR on TPS (b).
Figure 3
Figure 3
Measurement points for GRD in RANDO Alderson phantom. We inserted GRD in the cavities of the RANDO Alderson phantom and measured them at 1–16 measurement points.
Figure 4
Figure 4
Conversion curve of CT number to materials and mass density.
Figure 5
Figure 5
Comparison of IMRT dose profiles between TPS, 3DVH, COMPASS, and MC calculations at an isocenter: (a) lateral direction on the axial image at the isocenter; (b) vertical direction on the axial image at the isocenter.
Figure 6
Figure 6
Comparison of DVHs in anthropomorphic RANDO Alderson phantom between COMPASS, 3DVH, TPS, and MC for neck plan.
See this image and copyright information in PMC

References

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