Prog Med Phys.  2023 Jun;34(2):15-22. 10.14316/pmp.2023.34.2.15.

Comparison between Old and New Versions of Electron Monte Carlo (eMC) Dose Calculation

• Jung S
• Son J
• Jin H
• Kang S
• Park JM
• Kim Ji
• Choi CH

• KMID: 2543916
• DOI: http://doi.org/10.14316/pmp.2023.34.2.15

Abstract

This study compared the dose calculated using the electron Monte Carlo (eMC) dose calculation algorithm employing the old version (eMC V13.7) of the Varian Eclipse treatment-planning system (TPS) and its newer version (eMC V16.1). The eMC V16.1 was configured using the same beam data as the eMC V13.7. Beam data measured using the VitalBeam linear accelerator were implemented. A box-shaped water phantom (30×30×30 cm³ ) was generated in the TPS. Consequently, the TPS with eMC V13.7 and eMC V16.1 calculated the dose to the water phantom delivered by electron beams of various energies with a field size of 10×10 cm 2 . The calculations were repeated while changing the dose-smoothing levels and normalization method. Subsequently, the percentage depth dose and lateral profile of the dose distributions acquired by eMC V13.7 and eMC V16.1 were analyzed. In addition, the dose-volume histogram (DVH) differences between the two versions for the heterogeneous phantom with bone and lung inserted were compared. The doses calculated using eMC V16.1 were similar to those calculated using eMC V13.7 for the homogenous phantoms. However, a DVH difference was observed in the heterogeneous phantom, particularly in the bone material. The dose distribution calculated using eMC V16.1 was comparable to that of eMC V13.7 in the case of homogenous phantoms. The version changes resulted in a different DVH for the heterogeneous phantoms. However, further investigations to assess the DVH differences in patients and experimental validations for eMC V16.1, particularly for heterogeneous geometry, are required.

Keyword

Electron dose calculation; eMC; Eclipse; Treatment-planning system

Figure

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  Fig. 1 Geometry for electron Monte Carlo calculation. (a) Homogeneous water phantom, (b) homogeneous bone or lung phantom, (c) heterogeneous bone or lung phantom, and (d) heterogeneous bone and lung phantom.

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  Fig. 2 Percent depth dose (PDD) of 6-MeV electron beam calculation using (a) electron Monte Carlo (eMC) V13.7, (b) eMC V16.1, and (c) comparison between eMC V13.7 and eMC V16.1 using three-dimensional Gaussian "low" smoothing and (d) "medium" smoothing. (e–h) The PDD ranges from 70%–105% for (a), (b), (c), and (d). 3D, three-dimensional.

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  Fig. 3 Percent depth dose (PDD) of 12-MeV electron beam calculation using (a) electron Monte Carlo (eMC) V13.7, (b) eMC V16.1, and (c) comparison between eMC V13.7 and eMC V16.1 using three-dimensional Gaussian “low” smoothing and (d) “medium” smoothing. (e–h) The PDD ranges from 75%–105% for (a), (b), (c), and (d). 3D, three-dimensional.

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  Fig. 4 Lateral dose profile of 6-MeV electron beam calculation using (a) electron Monte Carlo (eMC) V13.7, (b) eMC V16.1, and (c) comparison between eMC V13.7 and eMC V16.1 using three-dimensional Gaussian "low" smoothing and (d) "medium" smoothing. (e–h) The percent depth dose ranges from 80%–105% for (a), (b), (c), and (d). 3D, three-dimensional.

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  Fig. 5 Lateral dose profile of 12-MeV electron beam calculation using (a) electron Monte Carlo (eMC) V13.7, (b) eMC V16.1, and (c) comparison between eMC V13.7 and eMC V16.1 using three-dimensional Gaussian "low" smoothing and (d) "medium" smoothing. (e–h) The percent depth dose ranges from 80%–105% for (a), (b), (c), and (d). 3D, three-dimensional.

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  Fig. 6 Dose-volume histogram for each geometry calculated using electron Monte Carlo (eMC) V13.7 and eMC V16.1; (a) homogeneous water phantom (b) homogeneous bone phantom, (c) heterogeneous lung phantom (denoted as bone hetero), (d) heterogeneous bone phantom (denoted as lung hetero) and (e) bone and lung phantom (denoted as mixed hetero). VOI, volumes of interest.

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  Fig. 7 Percent depth dose for each geometry calculated using electron Monte Carlo (eMC) V13.7 and eMC V16.1: (a) homogeneous bone phantom, (b) heterogeneous bone phantom (denoted as bone hetero), (c) heterogeneous lung phantom (denoted as lung hetero), and (d) bone and lung phantom (denoted as mixed hetero).

Reference

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