en Nuclear Medicine Nuclear Medicine گزارش کوتاه Short Report <p><strong>Background:</strong> The effectiveness and safety of brachytherapy treatment is mainly concerned with the calibration of sources and their traceability to internationally accepted Standards. Secondary Standard Dosimetry Laboratory (SSDL) does not offer calibration of ionization chambers with gamma-ray spectrum of high dose rate source ¹⁹²Ir . This work has been carried out to calibrate the high dose rate (HDR) ¹⁹²Ir sources. <strong>Materials and Methods:</strong> An interpolation procedure, using calibrations above 1.25 MeV (⁶⁰Co), and below 135 kV X-rays (61.1 keV), the exposure-weighted average energy 397 keV of ¹⁹²Ir is employed. Using Farmer ionization chamber HDR ¹⁹²Ir source has been calibrated by free in-air measurement technique and then the calibrated source has been used to calibrate well-type ionization chamber. <strong>Results:</strong> Difference between in-air measurement and that of manufacturer&rsquo;s remained within &plusmn; 3%, and the difference between in-air measurement and well-type chamber remained within &plusmn; 1%. Comparison between well-type measurements and manufacturer values shows differences less than &plusmn; 2%. All these differences are within the acceptable tolerance limits. <strong>Conclusion:</strong> The method presented shows good degree of accuracy so that the traceability of calibration is assured. Installation of a new brachytherapy source needs to be calibrated by in-air measurement technique and then this calibrated source should be used for well chamber calibration. Brachytherapy community is suggested to calibrate their sources with this method.</p> Brachytherapy, calibration, ionization chamber, HDR. 189 193 http://ijrr.com/browse.php?a_code=A-10-1-471&slc_lang=en&sid=1 M.A. Gadhi 790031947532846007511 790031947532846007511 No Bahawalpur Institute of Nuclear Medicine and Oncology (BINO) Bahawalpur, Pakistan S.A. Buzdar saeed.buzdar@iub.edu.pk 790031947532846007512 790031947532846007512 Yes Department of Physics, The Islamia University of Bahawalpur, Pakistan M. Afzal 790031947532846007513 790031947532846007513 No Department of Physics, The Islamia University of Bahawalpur, Pakistan Sh. Fatmi 790031947532846007514 790031947532846007514 No Bahawalpur Institute of Nuclear Medicine and Oncology (BINO) Bahawalpur, Pakistan M.S. Akhtar 790031947532846007515 790031947532846007515 No Bahawalpur Institute of Nuclear Medicine and Oncology (BINO) Bahawalpur, Pakistan A.H. Nizamani 790031947532846007516 790031947532846007516 No Department of Physics, University of Sind, Jamshoro, Hyderabad, Pakistan