A TLD system based on lithium borate for the measurement of doses to patients undergoing medical irradiation

A dosimetry system has been developed which is especially suited to the measurement of doses to patients undergoing irradiation for medical purposes. It is a TLD system based on lithium borate which has been used both in powder form and made up into solid discs by incorporation within PTFE. The predominant advantages of this material over other more widely used TLD materials are its closer approximation to soft tissue, its simple glow curve which eliminates the need for complicated annealing procedures and its low cost. The luminescence from the lithium borate is measured with a specially designed reader which uses radiofrequency heating. At present, using lithium borate powder, the system is capable of measuring doses down to 10 mrad and using lithium borate/PTFE discs it can measure down to 50 mrad with adequate precision. Preliminary measurements on solid glassy discs of lithium borate suggest that this form of the material may in some respects be superior for patient dosimetry.