Journal List > Prog Med Phys > v.26(2) > 1098506

TOOLS
Lee, Lim, Lee, Yi, Rhee, Kang, and Jeong: Development of Monitor Chamber Prototype and Basic Performance Testing
Original Article

Progress in Medical Physics 2015;26(2):99-105.

Published online: 20 June 2015

DOI: https://doi.org/10.14316/pmp.2015.26.2.99

Development of Monitor Chamber Prototype and Basic Performance Testing

Mujin Lee, Heuijin Lim, Manwoo Lee, Jungyu Yi, Dong Joo Rhee, Sang Koo Kang, Dong Hyeok Jeong

Research Center, Dongnam Inst. of Radiological & Medical Sciences, Busan, Korea

Correspondence: Dong Hyeok Jeong (physics7@empas.com) Tel:82-51-720-5813, Fax:82-51-720-5826

Received 28 May 2015       Revised 12 June 2015       Accepted 13 June 2015

Copyright © 2015 Korean Society of Medical Physics

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.

Keywords: Monitor chamber, Linac, Dosimetric characteristics

References

1. Greene D, Williams PC. Linear Accelerators for Radiation Therapy. 2nd ed.Taylor & Francis Group;New York: 1997. ), pp.p. 94–107.
2. Podgorsak EB. Review of Radiation Oncology Physics: A Handbook for Teachers and Students. International Atomic Energy Agency;Vienna, Austria: 2003. ), pp.p. 125–126.
3. Khan FM. The Physics of Radiation Therapy. 4th ed.Lippincott Williams & Wilkins;Philadelphia: 2010. ), pp.p. 162–163.
4. ICRP Ref-32/147/07. Preventing Accidental Exposures from New External Beam Radiation Therapy Technologies. International Commission on Radiological Protection;Ottawa, Canada: 2009. ), pp.p. 51–51.
5. MaShani G. Radiation Dosimetry. 2nd ed.CRC Press;New York: 2000. ): pp.p. 85–220.
6. IEC 60977: Medical electrical equipment-Medical electron accelerators-Guidelines for functional performance characteristics. edition 2. .0, International Electrotechnical Commission, Geneva, Switzerland (. 2008.
7. IEC 60731: Medical electrical equipment-Dosimeters with ionization chambers as used in radiotherapy. International Electrotechnical Commission, Geneva, Switzerland (. 2011.
8. ARPNSA Fact Sheet 24: Specifying the polarity of the polarizing voltage of an ionisation chamber. Australian Radiation Profection and Nuclear Safety Agency (. 2011.
9. Keithley 6517B–901–01: Model 6517B Reference Manual. Rev. B, Keithley Instruments, Inc, Ohio (. 2009. ), pp.93–93.
10. Macleod P. A Review of Flexible Circuit Technology and its Applications. PRIME Faraday Partnership;Loughborough University, UK: 2002. ): pp.p. 1–5.

Fig. 1.
Location of monitor chamber in the medical linac head.
pmp-26-99f1.tif
Fig. 2.
Basic circuit for charge measurement using monitor chamber.
pmp-26-99f2.tif
Fig. 3.
Design of FPCB and baseplate for monitor chamber.
pmp-26-99f3.tif
Fig. 4.
Cross-sectional structure of the monitor chamber prototype.
pmp-26-99f4.tif
Fig. 5.
Photography of the monitor chamber prototype.
pmp-26-99f5.tif
Fig. 6.
Monitor chamber prototype testing using Cobalt-60 irradiator and electrometer.
pmp-26-99f6.tif
Fig. 7.
Operation of integration circuit in the electrometer.
pmp-26-99f7.tif
Fig. 8.
Saturation characteristics for monitor chamber prototype.
pmp-26-99f8.tif
Fig. 9.
Stability of measured charge around the 300 V.
pmp-26-99f9.tif
Fig. 10.
Monitor chamber test for dose linearity.
pmp-26-99f10.tif
Table 1.
Measured transmission factor for the monitor chamber in Co-60 gamma rays.
Open With monitor chamber Transmission factor
12.590 nC±0.025% 12.680 nC±0.025% 0.9929±0.035%
TOOLS
Similar articles