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KMID : 1164220210330010079
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Journal of Korean Society for Radiotherapeutic Technology
2021 Volume.33 No. 1 p.79 ~ p.88
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Evaluation of the usefulness of Bolus, which combines Step Bolus and 3D Bolus
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Lee Chang-Suk
Chae Moon-Ki
Park Byung-Suk
Kim Sung-Jin
Joo Sang-Kyoo
Park Yong-Chul
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Abstract
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Objectives: Bolus, which combines 3D-bolus and Step-bolus, was produced and its usefulness is evaluated.
Materials and Methods: A Bolus was manufactured with a thickness of 10mm and 5mm using a 3D printer (3D printer, USA), and a Step Bolus of 5mm was bonded to a 5mm thick bolus. In order to understand the characteristics of Step bolus and 3D bolus, the differences in relative electron density, HU value, and mass density of the two bolus were investigated. These two Bolus were applied to anthropomorpic phantom to confirm its effectiveness. After all contouring of the phantom, a treatment plan was established using the computed treatment planning system (Eclipse 16.1, Varian medical system, USA). Treatment plan was performed using electron beam 6MeV, nine dose measurement points were designated on the phantom chest, air-gap was measured at that point, and dose evaluation was performed at the same point for each bolus applied using a glass dosimeter (PLD).
Results: Bolus, which combines 3D-bolus 5mm and Step-bolus 5mm, was manufactured and evaluated compared with 3D-bolus 1cm. The relative electron density of 3D Bolus was 1.0559 g/cm2 and the step Bolus was 1.0590 g/cm2, which was different by 0.01%, so the relative electron density was almost the same. In the lightweight measurement of air-gap, the combined bolus was reduced to 54.32% for all designated points compared to 3D-bolus. In the dose measurement using a glass dose meter (PLD), the consistency was high in phantom using combined bolus at most points except the slope point.
Conclusion: Combined bolus made by combining 3D-bolus and Step-bolus has all the advantages of 3D-bolus and Step-bolus. In addition, by dose inaccuracy due to Air-gap, more improved dose distribution can be shown, and effective radiation therapy can be performed.
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KEYWORD
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3D Bolus, Setp Bolus, Combined Bolus, electron, MRM
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