RaySafe Pro-Stand, Руководство пользователя

Страница: 3 / 4

3
RaySafe Pro-Stand User Manual – Test procedure for Stand Alignment
TEST PROCEDURE FOR STAND ALIGNMENT
This is an example. Be sure to comply with your local regulations.
1. Remove objects between the focal spot and the table, e.g., compression device, diaphragms, cones, etc.
2. Make sure the X-ray machine film or digital detector is in place.
3. Place the stand on the X-ray machine imaging table or other surface enabling it to be positioned
perpendicular to the beam axis.
4. Place the 2-piece alignment device at the top and bottom of the Pro-Stand (Figure 3).
5. Rough alignment can be carried out using the collimator light with the room lights off. Make sure the
shadow of the middle bead (E) is in the centre of the cross at the foot of the stand. For mammography
machines, please adjust the angle by tilting the stand using the side screw.
6. Adjust the stand height (y) so the minimum enlargement in the table below is achieved (use Equation 1):
From geometry rules we get (x+y)/x= L
2
/L
1
, which means 1+y/x= (L
2
/L
1
), y/x= L
2
/L
1
-1. This is the same as the
enlargement factor E which consequently can be calculated in two ways:
Equation 1: E=y/x, and
Equation 2: E=(L
2
/L
1
)-1
y=Object to detector distance, x=Object to focal spot distance
L1=Object length, L2=Measured object length in image
Minimum Enlargement
Nominal Focal
Spot Size (F, mm)
Enlargement
F<0.4 >3
0.4<F<2.5 >2
F>2.5 >1
7. Make sure the A-B, C-D, A-C, or B-D beads are aligned/parallel with the X-ray tube anode-cathode axis.
E
A
B
C
D
L
1
L
2
x y
b
f
Figure 3. Pro-stand alignment