Cadaveric Organ Dose Measurement For Adult Females Undergoing Multi-Detector Computed Tomography Scans In Ultrahelical Acquisition Mode

Date(s) - 09/25/2012
3:30 pm

Lindsay Sinclair, BME-Medical Physics PhD Student

Since the inception of Computed Tomography in the 1970’s, the technology has experienced a growth and advancement that is unparalleled. While CT has allowed for great advances in the field of diagnostics, this progression has not ensued without careful attention to the radiation dose associated with its use. There remains a need to accurately assess organ doses that result from these procedures.

Cadaveric subjects are utilized for dose measurements in this study due to their extreme likeness to a patient. Griglock introduced a methodology for directly measuring internal organ doses in a human body.(Griglock 2012) This project serves to expand upon his methodology with the use of additional cadavers and the evaluation of ultrahelical acquisition mode. With multiple detector row computed tomography (MDCT), the acquisition mode commonly used is helical in nature. It involves rotating the x-ray tube and detector configuration, while the patient is moved on a table through the gantry. Recently, a new form of image acquisition has been introduced, ultra-helical. Ultrahelical acquisitions are similar to helical acquisitons, but employ a wider beam (40, 50, or 80 mm) for faster scan times and increased anatomical coverage. Optically stimulated luminescent dosimeters (OSLDs) are utilized in this study due to their high sensitivity. The dosimeter’s small size allows for dose measurement of internal organs with minimal disruption to the overall patient anatomy and dose distribution.

For a CT exam, the amount of radiation absorbed by a patient depends on many factors, including patient size and scanner-specific techniques. In order to account for this, several cadaveric subjects with varying body mass indexes (BMI) were utilized for organ dose measurement. In addition, a range of CT protocols was examined. In this way, a correlation between organ doses and adult female BMIs can be deduced, from which a clinical model for determining patient organ doses can originate. The purpose of this project is to directly measure organ doses for a range of MDCT protocols for the adult female.