Tohoku J. Exp. Med., 2002, 198 (3)

Stability of Electron-Beam Energy Monitor for Quality Assurance
of the Electron-Beam Energy from Radiotherapy Accelerators

KOICHI CHIDA,^1,2 HARUO SAITO,³ YOSHIHIRO TAKAI,³ MASAYUKI ZUGUCHI,¹ MASATOSHI MITSUYA,³
HIDEHARU SAKAKIDA,³ MASAHIRO KOHZUKI² and SHOGO YAMADA³

¹Department of Radiological Technology, College of Medical Sciences, Tohoku University, ²Department of Internal Medicine and Rehabilitation Science, Tohoku University Graduate School of Medicine, and ³Department of Radiology, Tohoku University School of Medicine, Sendai 980-8575

Information on electron energy is important in planning radiation therapy using electrons. The Geske 3405 electron beam energy monitor (Geske monitor, PTW Nuclear Associates, Carle Place, NY, USA) is a device containing nine ionization chambers for checking the energy of the electron beams produced by radiotherapy accelerators. We wondered whether this might increase the likelihood of ionization chamber trouble. In spite of the importance of the stability of such a quality assurance (QA) device, there are no reports on the stability of values measured with a Geske monitor. The purpose of this paper was therefore to describe the stability of a Geske monitor. It was found that the largest coefficient of variation (CV) of the Geske monitor measurements was approximately 0.96% over a 21-week period. In conclusion, the stability of Geske monitor measurements of the energy of electron beams from a linear accelerator was excellent.

Keywords —— electron-beam energy monitoring; electron therapy; Quality Assurance; radiation therapy

© 2002 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2002, 198, 197-201

Address for reprints: Koichi Chida, Department of Radiological Technology, College of Medical Sciences, Tohoku University, 2-1 Seiryoumachi, Aoba-ku, Sendai 980-8575, Japan.

e-mail: chida@rad.cms.tohoku.ac.jp