| Thorax Phantom Author: Katia Sourbelle |
A modification of the thorax FORBILD phantom for 4D imaging by Frank Bergner, Marc Kachelrieß is available here.
Figure 1: Representation of the bones of the Thorax Phantom.
Aims
To provide semi–anthropomorphic cone–beam rawdata for CT-examinations of the thorax.
Phantom Description
The Phantom should represent the important parts of the thorax which are usually visualised during the CT examination : lungs, heart, aorta, ribs, spine, sternum, and shoulders.
Thorax:
The lungs are represented by two ellipsoids and the heart by a sphere. The aorta consists of three joined cylinders (2 vertical and 1 horizontal), to represent its ascending and descending parts.
The ribs will be modelled by nine small joined
cylinders (Fig 2.a). In order to define the cylinders, we will say that their center lies
on a tilted ellipse with the co-ordinates {a cos(q ), b sin(q ), c sin(q )}, for q between
p /2 and 3p /2 with steps of p /10. The axes of the cylinders are parallel to the tangent
of the ellipse at the centers.
We will take 5*2 ribs for the whole thorax.
For the spine we use the model defined for the Cardio-Phantom (Stefan Ulzheimer, IMP) which will be built to evaluate the quality of CT images (Fig 2.b).
The Sternum will be represented by a box.
Figure 2: a)Rib consisting of nine cylinders aligned along a tilted ellipse. b)Model of the vertebra used for the Cardio-Phantom
Figure 3: Slice of the Phantom at z = 0, showing the different parts of the thorax. 1:lung, 2:heart, 3:sternum, 4:vertebra, 5:aorta, 6:rib. Image Size 40cm*40cm.
Shoulders:
The clavicle is represented by a cylinder and the shoulder blade by the half of an ellipse. In order to simulate the usual stark attenuation at the shoulders, we will modell them by two spheres.
Figure 4: Slice of the phantom at z =15, showing the modelling of the shoulders. 1:humerus, 2:clavicle, 3:sternum, 4:shoulder blade, 5:vertebra. Image Size 50cm*50cm
All bones are filled with marrow. The whole Phantom will be made of 271 basic objects. The exact definition of the phantom are given in the following tables. The units are cm for the lengths and g/cm3 for the densities. The relevant objects lie between z=-15 cm and z=+18 cm. The field of view is 50 cm.
| Object | Center | Axis | Parameters | Clip plane | Density | |
| Thorax | Cylinder | [0, 0, 0] | [0, 0, 1] | L=50 ax=20 ay=10 | 1.000 | |
| Arm L | Cylinder | [-20, 0, 17.5] | [0, 0, 1] | L=15 R=5 | 1.000 | |
| Arm R | Cylinder | [20, 0, 17.5] | [0, 0, 1] | L=15 R=5 | 1.000 | |
| Lunge L | Ellipsoid | [-10.5, 0, 0] | ax=7.5 ay=5.5 az=15 | 0.260 | ||
| Lunge R | Ellipsoid | [10.5, 0, 0] | ax=7.5 ay=5.5 az=15 | 0.260 | ||
| Heart | Shere | [0, 4, 0] | R=3.5 | 1.050 | ||
| Sternum | Box Box |
[0, 9, 2.5] [0, 9, 2.5] |
Lx=2.5 Ly=0.8 Lz=25 Lx=2 Ly=0.5 Lz=25 |
1.250 0.980 |
||
| Clavicle L | Cylinder Cylinder |
[-10, 5.5, 16] [-10, 5.5, 16] |
[20, 9, -2] [20, 9, -2] |
L=17 R=0.5 L=16.5 R=0.4 |
1.460 0.980 |
|
| Clavicle R | Cylinder Cylinder |
[10, 5.5, 16] [10, 5.5, 16] |
[20, -9, 2] [20, -9, 2] |
L=17 R=0.5 L=16.5 R=0.4 |
1.460 0.980 |
|
| Shoulder blade L | Ellipsoid_free
Ellipsoid_free |
[-12 ,-5, 15]
[-12 ,-5, 15] |
Ax[2,-1, 0] Ay[1, 2, 0] Ax[2,-1, 0] Ay[1, 2, 0] |
ax=4.5 ay=0.5 az=6
ax=4 ay=0.4 az=5.5 |
Z<15 | 1.460
0.980 |
| Shoulder blade R | Ellipsoid_free
Ellipsoid_free |
[12 ,-5, 15]
[12 ,-5, -15] |
Ax[2, 1, 0] Ay[-1, 2, 0] Ax[2,-1, 0] Ay[1, 2, 0] |
ax=4.5 ay=0.5 az=6
ax=4 ay=0.4 az=5.5 |
Z<15 | 1.460
0.980 |
| Humerus L | Sphere Sphere Sphere Sphere |
[-22, 0, 15] [-16.5, 0, 15] [-22, 0, 15] [-16.5, 0, 15] |
R=2.5 R=2.5 R=2 R=2 |
1.460 1.460 0.980 0.980 |
||
| Humerus R | Sphere Sphere Sphere Sphere |
[22, 0, 15] [16.5, 0, 15] [22, 0, 15] [16.5, 0, 15] |
R=2.5 R=2.5 R=2 R=2 |
1.460 1.460 0.980 0.980 |
||
| Aorta | Cylinder Cylinder
Cylinder |
[-2.5, -2.5, 0] [-1, 1, 7.5]
[-0.5, 4.5, 6] |
[0, 0, 1] [3, 7, 0]
[0, 0, 1] |
L=30 R=1 L=20 R=1
L=6 R=1 |
R(3,7,7.615)<2.982 R(3,7,7.615)>2.982 R(1, 2, -2.236)<-2.239 R(1, 2, -2.236) >-2.239 |
1.050 1.050
1.050 |
Table 1: Definition of the different parts of the phantom
| Object | Center | Axis | Param | Clip plane | density |
| Cylinder | [X, Y, Z] | [0, 0, 1] | L=2 R=1.75 | 1.920 | |
| Box | [X, Y-1.4, Z] | Lx=2.343 Ly=0.2 Lz=2 | 1.920 | ||
| Cylinder | [X, Y, Z] | [0, 0, 1] | L=2 R=1.5 | 1.180 | |
| Box | [X-2, Y-1.975, Z] | Lx=4 Ly=0.95 Lz=2 | R(-0.95, 2.828, 0) < -1.04893-0.318392
+0.947959 Y R(-2, 32, 0) > -2.19572-0.0623783 X+0.998053 Y |
1.920 | |
| Box | [X+2, Y-1.975, Z] | Lx=4 Ly=0.95 Lz=2 | R(-0.95, 2.828, 0) <
-1.04893 +0.318392 +0.947959 Y R(2, 32, 0)> -2.19572 +0.0623783 X +0.998053 Y |
1.920 | |
| Box | [X, 2.35+Y, Z] | Lx=1.6 Ly=0.3 Lz=2 | R(-2,4,0)> -2.37023
-0.447214 X +0.894427 Y R(-2,-4,0)< 2.37023 -0.447214 X -0.894427 Y |
1.920 | |
| Box | [X, -3.25+Y, Z] | Lx=0.8 Ly=1.6 Lz=2 | 1.920 | ||
| Cylinder | [X, Y-4.05, Z] | [0, 0, 1] | L=17 R=0.5 | Y < Y-4.05 | 1.920 |
Table 2: Definition of a vertebra at the position (X, Y, Z)
The phantom consists of 9 vertebras placed at X=0, Y=-5 and Z between –6 and 15.
The ribs lie on the ellipse of parameters a=-18.5, b=9, c=-5.5 .
All the cylinders composing a rib have a radius of 0.5. The inner cylinders for the marrowbone have a radius of 0.4.
| Center | Axis | Clip plane | density |
| x=5.716814 y=8.559509 z=-5.230811 |
17.594546 -2.781153 1.699593 |
r(1.907146,-0.481971,0.294538
) <5.451355 r(1.983271,-0.155425,0.094982 ) >1.953178 |
1.410 / 0.980 |
| x=10.874027 y=7.281153 z=-4.449593 |
14.966814 -5.290067 3.232819 |
r(1.710571,-0.853311,0.521468
) <7.622861 r(1.907146,-0.481971,0.294538 ) >5.451355 |
1.410 / 0.980 |
| x=14.966814 y=5.290067 z=-3.232819 |
10.874027 -7.281153 4.449593 |
r(1.281833,-1.268109,0.774956
) <7.228981 r(1.710571,-0.853311,0.521468 ) >7.622861 |
1.410 / 0.980 |
| x=17.594546 y=2.781153 z=-1.699593 |
5.716814 -8.559509 5.230811 |
r(0.495137,-1.594626,0.974494
) <3.123195 r(1.281833,-1.268109,0.774956 ) >7.228981 |
1.410 / 0.980 |
| x=18.500000 y=-0.000000 z=0.000000 |
-0.000000 -9.000000 5.500000 |
r(-0.495137,-1.594626,0.974494
) <-3.123195 r(0.495137,-1.594626,0.974494 ) >3.123195 |
1.410 / 0.980 |
| x=17.594546 y=-2.781153 z=1.699593 |
-5.716814 -8.559509 5.230811 |
r(-1.281833,-1.268109,0.774956
) <-7.228981 r(-0.495137,-1.594626,0.974494 ) >-3.123195 |
1.410 / 0.980 |
| x=14.966814 y=-5.290067 z=3.232819 |
-10.874027 -7.281153 4.449593 |
r(-1.710571,-0.853311,0.521468
) <-7.622861 r(-1.281833,-1.268109,0.774956 ) >-7.228981 |
1.410 / 0.980 |
| x=10.874027 y=-7.281153 z=4.449593 |
-14.966814 -5.290067 3.232819 |
r(-1.907146,-0.481971,0.294538
) <-5.45135 r(-1.710571,-0.853311,0.521468 ) >-7.622861 |
1.410 / 0.980 |
| x=5.716814 y=-8.559509 z=5.230811 |
-17.594546 -2.781153 1.699593 |
r(-1.983271,-0.155425,0.094982
) <-1.953178 r(-1.907146,-0.481971,0.294538 ) >-5.451355 |
1.410 / 0.980 |
Table 2: Definition of the 9 cylinders composing the rib at the position Z=0. The four other ribs are just translated to Z=± 3 and Z=± 6.
| View Phantom Definition (download as zip, 5k) |
| phantom syntax explanation |
| Other Phantoms | |||
| Abdomen | Head | Hip | Jaw |
| Lung | Thorax | High Contrast | Low Contrast |