Study of dosimetric methods in radiodiagnostic standard beams, with emphasis on computed tomography

• Grant number: 05/01432-5
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: October 01, 2005
• End date: July 31, 2006
• Field of knowledge: Engineering - Nuclear Engineering
• Principal Investigator: Linda Viola Ehlin Caldas
• Grantee: Ana Figueiredo Maia
• Host Institution: Instituto de Pesquisas Energéticas e Nucleares (IPEN). Secretaria de Desenvolvimento Econômico (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

The two most important dosimetric methods for diagnostic radiology beams are the thermoluminescence dosimetry and the measurements with ionization chambers. The main purpose of this work is to evaluate the performance of these two methods in diagnostic radiology and mammography standard beams established at the Calibration Laboratory of IPEN. Several types of thermoluminescence dosimeters, already available at the laboratory, and some ionization chambers will be utilized. Among the established standard beams, special attention will be given for the computed tomography beams. The possibility of determination of the main CT dose descriptors will be studied using the thermoluminescence dosimeters available at the laboratory, as well as ionization chamber not specific for this purpose. Practical tests in computed tomography equipment using these different techniques will be performed. The most utilized quantity in CT is the Computed Tomography Dose Index (CTDI). However, recent studies have shown that this dose quantity is not the most adequate for evaluation of doses concerning multi-slice procedures. The possibility of determination of the most appropriate dose quantities using thermoluminescence dosimeters and ionization chambers of small sensitive volume will be investigated. (AU)