Prog Med Phys.  2015 Jun;26(2):99-105. 10.14316/pmp.2015.26.2.99.

Development of Monitor Chamber Prototype and Basic Performance Testing

• Lee M
• Lim H
• Lee M
• Yi J
• Rhee DJ
• Kang SK
• Jeong DH

• KMID: 1889942
• DOI: http://doi.org/10.14316/pmp.2015.26.2.99

Abstract

The monitor chamber is a real time dosimetry device for the measurement and the control of radiation beam intensity of the linac system. The monitor chamber prototype was developed for monitoring and controlling radiation beam from the linac based radiation generator. The thin flexible printed circuit boards were used for electrodes of the two independent plane-parallel ionization chambers to minimize the attenuation of radiation beam. The dosimetric characteristics, saturation and linearity of the measured charge, were experimentally evaluated with the Co-60 gamma rays. The performance of the developed monitor chamber prototype was in an acceptable range and this study shows the possibility of the further development of the chamber with additional functions.

Keyword

Monitor chamber; Linac; Dosimetric characteristics

MeSH Terms

Electrodes
Gamma Rays

Figure

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  Fig. 1. Location of monitor chamber in the medical linac head.

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  Fig. 2. Basic circuit for charge measurement using monitor chamber.

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  Fig. 3. Design of FPCB and baseplate for monitor chamber.

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  Fig. 4. Cross-sectional structure of the monitor chamber prototype.

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  Fig. 5. Photography of the monitor chamber prototype.

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  Fig. 6. Monitor chamber prototype testing using Cobalt-60 irradiator and electrometer.

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  Fig. 7. Operation of integration circuit in the electrometer.

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  Fig. 8. Saturation characteristics for monitor chamber prototype.

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  Fig. 9. Stability of measured charge around the 300 V.

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  Fig. 10. Monitor chamber test for dose linearity.

Reference

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