J Korean Soc Ther Radiol Oncol.  2006 Jun;24(2):138-143.

Evaluation of the Long-Term Stability for the Cylindrical Ionization Chambers

• Rah JE
• Hong JY
• Kim GY
• Lim CI
• Jeong HK
• Shin DO
• Suh TS

Abstract

PURPOSE: To analyze the long-term stability of Farmer-type cylindrical ionization chambers by calibration factor provided from the KFDA (Korea Food Drug Administration)
MATERIALS AND METHODS
The cylindrical ionization chambers used in this study were the PTW 30001 (30006), 30013, 30002, 30004, 23333, the Capintec PR06C, the NE 2571, the Exradin A12 and the Wellhofer FC65G (IC70). We were analyzed that the N(k) and N(D,W) calibration factor for the cylindrical chambers and compared between the measured N(D,W) and calculated N(D,W) calibration factor.
RESULTS
We have observed that the long-term stability of the PTW 30013 (30006), the Wellhofer FC65G (IC70) and the NE 2571 has varied within 0.2%. The measured N(D,W) calibration factor was about 1.0% higher than the calculated N(D,W) that determined by the N(k) calibration factor.
CONCLUSION
The study has evaluated that the long-term stability of the cylindrical chambers through analysis for the Nk and N(D,W) calibration factor. It has contributed to the improvement of clinical electron dosimetry in radiotherapy centers.

Keyword

Nk calibration factor; ND; W calibration factor; Farmer type cylindrical chamber; Long-term stability

MeSH Terms

Calibration
Radiotherapy