Prog Med Phys.  2017 Dec;28(4):144-148. 10.14316/pmp.2017.28.4.144.

Dosimetric Impact of Ti Mesh on Proton Beam Therapy

• Cho S
• Goh Y
• Kim C
• Kim H
• Jeong JH
• Lim YK
• Lee SB
• Shin D

• KMID: 2401375
• DOI: http://doi.org/10.14316/pmp.2017.28.4.144

Abstract

When a high density metallic implant is placed in the path of the proton beam, spatial heterogeneity can be caused due to artifacts in three dimensional (3D) computed tomography (CT) scans. These artifacts result in range uncertainty in dose calculation in treatment planning system (TPS). And this uncertainty may cause significant underdosing to the target volume or overdosing to normal tissue beyond the target. In clinical cases, metal implants must be placed in the beam path in order to preserve organ at risk (OARs) and increase target coverage for tumors. So we should introduce Ti-mesh. In this paper, we measured the lateral dose profile for proton beam using an EBT3 film to confirm dosimetric impact of Ti-mesh when the Ti-mesh plate was placed in the proton beam pathway. The effect of Ti-mesh on the proton beam was investigated by comparing the lateral dose profile calculated from TPS with the film-measured value under the same conditions.

Keyword

Ti-mesh; Proton; Artifact; TPS; EBT3 film

MeSH Terms

Artifacts
Population Characteristics
Proton Therapy*
Protons*
Uncertainty
Protons

Figure

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  Fig. 2 (a) Phantom study on the effects of Ti-mesh on DS proton dose in TPS; (b) lateral dose profiles depending on depth calculated by proton convolution algorithm in TPS.

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  Fig. 1 The schematic of experiment setup for lateral profile measurements.

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  Fig. 3 (a) SOBP curve in 165 MeV DS proton beam; (b) lateral film dose profile measured depending on depth at gantry angle 0 degree.

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  Fig. 4 Lateral dose profile at the middle of the SOBP with and without the mesh plate at depth 1 cm in film measurement.

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  Fig. 5 Comparative analysis between dose profiles of film and TPS depending on gantry angle at depth 1 cm.

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