NURB phantoms - xcist/documentation GitHub Wiki

For these phantoms, use
cfg.callback_projector = 'C_Projector_NCAT';

Two programs, which are not part of CatSim, are used to produce phantoms in this format. These programs, developed by Paul Segars, et. al., are called NCAT and XCAT. Therefore, the resulting phantoms, and the functions associated with using them, often contain NCAT or XCAT in their names. Both NCAT and XCAT produce phantoms in the NURB format.

Note to GE’s academic collaborators: To obtain the software required to produce NCAT phantoms, please contact Paul Segars at [email protected].

NCAT and XCAT phantoms are described in files with the .nrb extension. This format is used to specify non-uniform rational b-spline (NURBS) objects for use with the ncat projector. There are m × n control points that specify a mesh that controls the shape of the NURBS object. For more information on NURBS, Wikipedia is a good resource. The files have a series of objects, with each object specified as follows:

**object_name
material_id
m :M
n :N

U Knot Vector
u(1)
...
u(n+4)

V Knot Vector
v(1)
...
v(m+4)

Control Points
c(1,1)
...
c(1,n)

c(2,1)
...
c(2,n)
...
...
c(m,1)
...
c(m,n)

The material_id is a number from 0 to 34 that specifies the material. The ncat materials are as follows:

Table 2: NCAT Materials

material_id	Material
0	ncat_water
1	ncat_muscle
2	ncat_lung
3	ncat_dry_spine
4	ncat_dry_rib
5	ncat_adipose
6	ncat_blood
7	ncat_heart
8	ncat_kidney
9	ncat_liver
10	ncat_lymph
11	ncat_pancreas
12	ncat_intestine
13	ncat_skull
14	ncat_cartilage
15	ncat_brain
16	ncat_spleen
17	ncat_iodine_blood
18	ncat_iron
19	ncat_pmma
20	ncat_aluminum
21	ncat_titanium
22	ncat_air
23	ncat_graphite
24	ncat_lead
25	ncat_breast_mammary
26	ncat_skin
27	ncat_iodine
28	ncat_eye_lens
29	ncat_ovary
30	ncat_red_marrow
31	ncat_yellow_marrow
32	ncat_testis
33	ncat_thyroid
34	ncat_bladder