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Browsing Research Articles by Author "Kiragga , Festo"

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    Calibration of Various Detectors for Commissioning of Total Body Irradiation for a New Installation in Maggiore Hospital, Trieste-Italy
    (African Journal of Medical Physics, 2023-07-30) Kiragga , Festo; Vidimari , Rosella
    Calibration of detectors: Gafchromic EBT3(GAF) and Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) was done under reference conditions for use in Total Body Irradiation (TBI) conditions. Three Source Axis Distances (SAD) were chosen: 5m, 4.5 m, and 4m with minimal or no backscatter from the wall. Lateral-Lateral (LL), gantry angle 90o, collimator angle 0o, and 6 MV energy were chosen with respect to the nature of the bunker. Percentage Depth Doses (PDDs) were evaluated, first with a big water phantom using calibrated dosimetry diode, P and then also with RW3 slab phantom (30 x 30 x 30 cm3) at the three positions using GAF. Afterwards, the PDDs were then compared allowing the beam to be characterized in different setups. MOSFETs calibration factors corresponding to each channel were also obtained by first measuring the average dose with a Farmer chamber under reference conditions in the same position. Then the MOSFETs were cross-calibrated against the Farmer chamber. A length of 140 cm (pediatric) was found to be in the flatness region with a dose variation of 3%. GAF, and MOSFETs were calibrated and a calibration curve was plotted for GAF while a table of calibration factors was made for the MOSFETs to be used in TBI conditions. A dose variation of less than 2% was achieved between the Farmer chamber and GAF readings at similar points in the RW3 phantom. The beam characteristics were important parameters to understand the behavior of the beam in non-reference conditions (TBI conditions). These were within the tolerance range as dose variations of up to ± 10% are allowed in TBI conditions. The doses measured with the calibrated Farmer chamber and GAF were compared with less than 2% difference and this meant that the GAF can be used in any TBI setup. Therefore, the bunker was found fit for carrying out the TBI technique, particularly for pediatrics.