Characterising Silicon Diode response for radiation measurements
Abstract
X-ray radiation has been used in the treatment of cancer since its discovery in 1895. It was
found that incorrect use of x-radiation can cause irreversible damage. It was necessary to
introduce diode in-vivo dosimetry for x-radiation measurement to control the dose
administered to patients.
This study focuses on the characteristics of a p-type silicon diode as an x-radiation detector.
The investigation involved measurement of the response of the diode under different
conditions, which include gantry angle, field size, source to surface distance, off axis and
wedge angle, in order to determine the optimum position for diode placement for both flat
and curved surface.
These conditions were varied and the corresponding change in response of the diode noted.
The measurements were done on both the flat and curved surface of a phantom designed and
built specifically for this project. Two diodes (old diode and new diode) were used in the
investigation to observe the change in diode sensitivity after prolonged use. The results were
also compared to those of other workers [8,10,15,20,23].
The results showed that the old and new diode both exhibited similar trends in all
measurements though notable difference in their sensitivity can be observed. Large
percentage deviations about ± 7 % were observed in the curved surface measurements. The
diodes responded differently between the curved and flat surface measurements. The project
showed that proper diode placement is necessary especially when performing measurements
on curved surfaces.
Sponsor
Germany Academic Exchange Services (DAAD)Additional Notes
Scholarship award