Fabrication of Free Air Well Type Ionization Chamber and Calculational Assessment and Measurement of Its Operational Characteristics

Publish Year: 1386
نوع سند: مقاله ژورنالی
زبان: English
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شناسه ملی سند علمی:

JR_IJMP-4-2_001

تاریخ نمایه سازی: 5 شهریور 1402

Abstract:

Introduction: Well type ionization chamber is a measuring device which is used to determine the activity of brachytherapy sources. The chamber has a cylindrical volume in which a cylindrical tube is mounted in the middle of the chamber. For the measurements, the brachytherapy sources are transferred to the middle of the tube. Materials and Methods: For designing the well type chamber, the measurement principals of well type chambers were considered and MCNP-۴C code as a calculation tool was used. The designed chamber was simulated and the response of the chamber was evaluated. In this investigation, the chamber operational parameters such as operating voltage, leakage current, reproducibility, reference measuring point, recombination and polarization factors as well as response stability for ۱۳۷Cs, ۵۷Co and ۲۴۱Am sources were studied. Results: The chamber leakage currents at the operating voltage in comparison to the chamber response for the measurement of the above mentioned sources were negligible. The responses of the fabricated chamber for these sources are reproducible and its reference measurement position for these sources was obtained at ۶ cm from the bottom of the chamber. The recombination factor for the well type chamber was negligible and the polarization factor is close to ۱. Therefore, these two factors were not considered in the measurements. The reproducibility of the measurements in different intervals shows the stability of the chamber response for each source. Also the results of the chamber current measurement in term of source strength were compared to the response of the simulated chamber for different source positions and energy ranges of the used sources. Discussion and Conclusion: The results show that the measurement of the reference positions for each source in the simulated and fabricated chamber is quite in a good agreement. Regarding the reliable operational properties of the fabricated chamber, this chamber can be used to determine the activities of brachytherapy sources in which the energy ranges are greater than ۵۰ KeV.

Authors

Koroush Arbabi

Ph.D. student in medical physics, Agricultural, Medical & Industrial Research School (AMIRS), Nuclear Sciences & Technology Research Institute (NSTRI), Atomic Energy Organization of Iran (AEOI), Tehran, Iran

Gholamreza Raisali

Associate Professor, Nuclear Engineering, Radiation Application Research School (RARS), NSTRI, AEOI

Masoomeh Dehghani Moghadam

M.Sc. in Nuclear Physics, Deputy of Nuclear Research & Technology, AEOI, Tehran, Iran

Mostafa Ghafoori

M.Sc. in Nuclear Engineering, AMIRS, NSTRI, AEOI, Tehran, Iran

Arjang Shahvar

B.Sc. in Nuclear Physics, AMIRS, NSTRI, AEOI, Tehran, Iran

Said Hamidi

Assistant Professor, Nuclear Physics Dept., Physics Group, Basic Sciences Faculty, Arak University, Arak, Iran