Malaysian Journal of Analytical Sciences Vol 18 No 1 (2014): 7 – 14

 

 

 

LONG TERM STABILITY OF FARMER TYPE IONIZATION CHAMBER CALIBRATION COEFFICIENT BELONGING TO LOCAL RADIOTHERAPY CENTRES IN MALAYSIA

 

(Kestabilan Jangka Panjang Pekali Tentukuran Kebuk Pengionan Jenis Farmer Kepunyaan Pusat Radioterapi di Malaysia)

 

A.M. Mukhtar¹, S.B. Samat¹*,  M.T. Dolah²

 

¹School of Applied Physics,

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

²Secondary Standard Dosimetry Laboratory,

Malaysian Nuclear Agency (Nuclear Malaysia),

43000 Kajang, Selangor, Malaysia

 

*Corresponding author: sbsamat@ukm.my

 

 

Abstract

The accuracy of the ionization chambers’ calibration coefficient is one of the factors that would contribute to efficient radiotherapy treatment. The IAEA therefore has recommended that an ionization chamber be calibrated every year, with a condition that the deviations between the previous and new calibration coefficients N_D,w should not differ by ±1.5%. It has been identified that Farmer type ionization chambers is the most popular ionization chamber among the radiotherapy centres in Malaysia. For this reason, the purpose of this work is to evaluate the calibration coefficients’ long term stability of the Farmer type ionization chambers. A total of 33 Farmer type ionization chambers were studied and the mean µ of the N_D,w deviation together with its standard error SE were calculated. This µ±SE will be used to measure stability of N_D,w. Our results showed that most chambers have µ±SE lies within the ±1.5%. It is thus concluded that most of the Farmer type ionization chamber were stable in their N_D,w and safe to be used for radiotherapy treatment.

 

Keywords: Farmer type ionization chambers, radiotherapy centres, calibration coefficients N_D,w, stability.

 

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