Affiliations: Radiobiology Program, Loma Linda University, Chan Shun
Pavilion, Room A1010, 11175 Campus Street, Loma Linda, CA 92354, USA
Note: [] Corresponding author: André Obenaus, PhD, Radiobiology
Program, Loma Linda University, Chan Shun Pavilion, Room A1010, 11175 Campus
Street, Loma Linda, CA, 92354 USA. Tel.: +1 909 558 7108; Fax: +1 909 558 0320;
E-mail: aobenaus@dominion.llumc.edu
Abstract: The use of non-invasive imaging modalities, including micro X-ray
computed tomography (micro-CT), is starting to be used extensively to
investigate normal and pathological states in a variety of animal models. This
increased use of in vivo imaging requires a better understanding of the
radiation dose delivered during routine imaging. Our laboratory is equipped
with a micro X-ray computer tomography unit (MicroCAT II®, ImTek Inc.,
Knoxville, TN) with a 60 kVp X-ray source and a reconstruction volume
resolution as low as 15 microns that is used for proton radiation therapy
treatment planning. In order to determine the X-ray radiation dose delivered to
skin and internal organs by our micro-CT we implanted new, calibrated Harshaw
TLD-100 Lithium Fluoride thermo-luminescent detectors (TLDs), into five C57BL/6
male mice and ten Sprague-Dawley male rats. Implants were made into the brain,
heart, right lung, liver, stomach, cecum, bladder, dorsal thoracal skin and
ventral abdominal skin in each animal. Animals were each scanned once using 50
kVp at 800 μA with 360 projections per scan with each projection lasting 400
msec. Using the TLD readings, the radiation dose from each body location was
measured with the dorsal thoracal skin receiving the highest average dose (4.5
cGy, mouse; 2.8 cGy, rat) and other internal organs receiving significantly
lower average doses. Therefore, knowing the radiation doses delivered during
routine imaging, care can be taken to avoid significant and potentially lethal
doses of radiation.
