SAIP 2011

Remote detection of light organic elements using PET

15 Jul 2011, 08:30

15m

Acro3

Oral Presentation Track F - Applied and Industrial Physics Applied

Speaker

Mr Martin Cook (University of Johannesburg)

Description

We look at the use of Positron Emission Tomography to detect light organic elements in two different contexts, namely to locate diamonds within partially crushed kimberlite (Mineral PET), and to locate buried land mines. Light organic elements such as carbon have traditionally proved difficult to locate, and currently mines crush rock down to a fine size, and then employ manual sorting methods to find diamonds. If diamond bearing rocks could be identified before the final crush, up to 98% of the electricity and water used for crushing could be saved, and larger diamonds preserved. The proposed technique is to use bremsstrahlung from a 40 MeV electron source to excite the giant dipole resonance in target nuclei, which have a large branching ratio to decay by emission of a neutron, forming PET isotopes. Such isotopes release positrons, which annihilate to create back-to-back 511 keV gamma rays. A 3D density map of possible sources allows the identification of hotspots. Complications arise from having to account for the excitation of many different nuclei, and having to distinguish diamond from homogeneously distributed carbon. In order to be industrially feasible, small diamonds need to be located, requiring significant advances in detection and image processing. We will look at simulations of the process, imaging algorithms, quantifying radiation doses and detector technologies. Land mines are a huge global problem. 2009 estimates place the number of buried land mines at over 100 million, covering approximately 3 000 square kilometers of land worldwide. Between 1999 and 2008, these have lead to 73 576 mine casualties in 119 countries. Overall demining programme costs in third world environments are typically one to two million dollars per square kilometer of cleared land. Advances in land mine technology mean that mines can contain little or no metal, making demining an expensive, slow and dangerous activity. Most common elements in explosives are PET emitters, including Oxygen, Carbon, Nitrogen and Flourine, raising the possibility that PET could provide an effective method of mine detection.