A carbon nanotube-based radiation sensor

Dosimetric measurements and monitoring play an essential role in radiotherapy. Because of their sensitivity and relatively flat energy response ionization chambers remain the most important dosimeters. However, ionization chambers usually have large physical dimensions and require high bias voltages to achieve acceptable ionization collection efficiency. Such disadvantages limit their applications for in vivo dose measurements. The availability of novel materials such as carbon nanotubes (CNTs) has created the potential to miniaturize traditional ionization chambers and lower the bias voltages. This paper describes a new CNT-based radiation sensor. In the first stage, characteristics of the sensor were examined with two stainless steel electrodes. The sensor displayed excellent linear responses to exposure and showed accurate responses to oblique incident beam measurements. These experimental results showed that the prototype sensor is suitable for studying the ionization collection efficiency of CNTs. In the second stage, square- and irregular-shaped CNTs electrodes were designed. Saturation characteristics of the sensor with the CNTs electrodes were measured. Experimental results and ongoing work are presented and discussed in this paper.