GE BrightSpeed Elite, Руководство по предварительной установке

Страница: 91 / 170

GE H
EALTHCARE

D
IRECTION
5141177-100, R
EVISION
14 B
RIGHT
S
PEED
E
LITE
, E
DGE
, E
XCEL
: P
RE
-I
NSTALLATION
Chapter 4 - Room Planning Page 91
4 – Room Pla
nning
Section 10.0

Radiation Protection
NOTICE Scanner-room shielding requirements should be reviewed by a qualified radiological health
physicist taking into consideration:
•
Scatter radiation levels within the scanning room (see Figure 4-23 )
• Equipment placement
• Weekly projected work-loads (# patient/day technique (kvp*ma))
• Materials used for construction of walls, floors, ceiling, doors, and windows
• Access to surrounding scan room areas
• Equipment in surrounding scan room areas (e.g., film developer, film storage)
Figure 4-22 depicts measurable radiation levels within the scanning room while scanning a 32 cm
CTDI phantom (body) and a 20 cm water phantom (head) with the technique shown. The mAs, kV
and aperture scaling factors shown in
Table 4-11 can be used to adjust exposure levels to the scan
technique used at the site.
Note: Actual measurements can vary. All measurements have an accuracy of ± 20% because of
measurement equipment, technique, and system-to-system variation.
Use the correction factors shown in
Table 4-11 to adjust exposure levels to the usual scan
technique at your site.
NOTICE The units of measure used for radiation levels have been changed in this publication, from
mR (millirads) to

Gy (micrograys). The conversion factor is:
1 mR = 8.69

Gy
CHANGED PARAMETER MULTIPLICATION FACTOR
mAs new mAs/100
80 kV 0.21
120 kV 0.71
140 kV 1.0
4 x 3.75mm images 0.82
16 x 0.625 LD
8 x 1.25 LD
4 X 2.5 LD
Fluro 5mm
0.59
4 x 1.25 LD
5mm (1i)
Fluro 2.5 mm
0.40
1 x 1.25mm images 0.20
2 x 0.625 LD
1 x 1.25
0.10
Table 4-11 Shielding Requirements Scaling