Prog Med Phys.  2018 Dec;29(4):115-122. 10.14316/pmp.2018.29.4.115.

On the Use Factor Analysis and Adequacy Evaluation of CyberKnife Shielding Design Using Clinical Data

• Cho YR
• Jung H
• Lee DH

• KMID: 2434645
• DOI: http://doi.org/10.14316/pmp.2018.29.4.115

Abstract

Although the current internationally recommended standard for the use factor (U) applied to CyberKnife is 0.05 (5%), the CyberKnife shielding standard is applied more stringently. This study, based on clinical data, was aimed at examining the appropriateness of existing shielding guidelines. Sixty patients treated with G4 CyberKnife were selected. The patients were divided into two groups, according to whether they underwent skull or spine tracking. Based on the results, the use factors for each wall ranged from 0.028 (2.8%) to 0.031 (3.1%) for the intracranial treatment and 0.020 (2.0%) to 0.022 (2.2%) for the body treatment. Excessive barrier thickness resulted in inefficient use of space and higher cost to the institutions. Furthermore, because the use factor is influenced by the position of the robot, the use factor determined based on the clinical data of this study would facilitate more reasonable treatment room design.

Keyword

Radiation protection; Radiation shielding design; G4 CyberKnife; Use factor

MeSH Terms

Factor Analysis, Statistical*
Fibrinogen
Humans
Radiation Protection
Skull
Spine
Fibrinogen

Figure

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  Fig. 1 G4 CyberKnife treatment room coordinate system. Draw of the CyberKnife treatment room with indicated dimensions and coordinate system.

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  Fig. 2 Unit coordinate transformation through rotation by θ about z axis.

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  Fig. 3 The history of prescribed iso-dose line (a), the number of beam (b) and total MU of patients (c).

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  Fig. 4 The projection of radiation beams for each tracking mode in CyberKnife, (a) skull tracking-beam intensity, (b) spine tracking-beam intensity (Superior: Front wall, Inferior: Back wall, Anterior: Ceiling, Posterior: Floor).

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