It were performed 135 measurements in a 16-slice CT Scanner,
without and with bismuth breast shields,
in different configurations: with protection but without sponge,
with protection with a sponge,
with protection with two sponges and the bismuth protection attached to the detectors window at the gantry.
Dose measurements on phantom (Cardinal Health 76 415) with an ionization chamber were performed using the routine thorax CT protocol.
Image quality control tests were performed using the phantom (Gammex 464) with and without bismuth breast protection in different configurations.
Dose determination
To determine and evaluate the dose,
CTDIw,
CTDI vol and DLP values were calculated for the routine thorax protocol with 130 kVp,
70 mAs,
1,2mm collimation and rotation time of 0.6 s,
without and with bismuth breast shields,
in different configurations (Fig. 1).
Image Quality Control
To the image quality evaluation it was used a chest and abdomen protocol,
bismuth protection and Gammex 464 phantom composed of solid water (0 ± 5HU) with length of 16 cm,
20 cm in diameter and divided into four modules.
The module 1 allows to evaluate the alignment,
positioning and accuracy of HU values in cylinder material equivalent to bone,
polyethylene,
water,
acrylic and air.
The module 2 evaluates the low-contrast resolution constituted by a series of cylinders of different diameters (2,
3,
4,
5,
6,
and 25 mm).
The module 3 is constituted by an equivalent material to the tissues and evaluates the uniformity or homogeneity of HU values.
The module 4 allows to evaluate the resolution and high contrast resolution and includes eight patterns 4,
5,
6,
7,
8,
9,
10 and 12 lines pair per millimeter (lp/mm).