Table 1.

The CT values of each structure with their mass density and relative electron density values obtained from TPS.

S. No.	Structure	CT value	Mass density	Relative electron density
1	Bone	1000 or more	1.86	1.87
2	Muscle (skeletal)	45–100	1.05	1.0505
3	Adipose tissue	0–50	0.92	0.8867
4	Air	0	0.0012	0.0074
5	Prespex	100–150	1.07	1.0701
6	Couch surface	−300 HU	0.0071	0.0071
7	Couch interior	−1000 HU	0.0011	0.0011