Biomedical subjects

C N deSouza

Publications and source records attributed to C N deSouza.

2 recordsLinked to original sources

PubMed1995

Evaluation of a well-type ionization chamber for calibration of HDL and LDR brachytherapy sources.

The Atomlab 44D well-type ionization chamber is being evaluated for calibration of high dose rate (HDR) Ir-192 and low dose rate (LDR) Cs-137 sources. The chamber has a flat response (sweet spot) of +/- 0.5% along approximately 3.5 cm for an Ir-192 HDR linear source and 3 cm for a Cs-137 LDR spherical source. The short-term stability of the chamber was determined using a cylindrical Cs-137 source positioned in the sweet spot region. The chamber response over a range of 17.4 mCi (644 MBq, Cs-137) and 8.82 Ci (326 GBq, Ir-192) is evaluated. The chamber may be used for calibrating the activities of both HDR Ir-192 and LDR brachytherapy sources.

Brachytherapy↗

PubMed1994

Electron energy constancy check using a five-chamber detector array.

Two methods are shown here to determine the 50% depth ionization (d50) using buildup materials of different thickness placed on top of a five-chamber detector array. In the first method, two sets of different thickness buildup material are required to perform the check, one set for checking 6 and 9 MeV, while another set is used for 12, 16, and 20 MeV electron beam from a Varian Clinac 2100C. The second method only requires two data points to determine the d50 depth for each energy. The d50 depths determined were compared with the d50 depth obtained using a water phantom with ionization chamber measurements. The method is simple to use especially for departments that use a similar detector to perform quality assurance tests such as output/symmetry/flatness check.

Electrons↗