Dear Jagalingam P,

please have a look at my recent answer to a similar question:

https://www.researchgate.net/post/Where_can_I_get_CT_images_probably_with_MRI_support_scanned_at_various_radiation_doses

Please have a look at the sources given therein.

In addition please have a look at:

http://www.cancerimagingarchive.net/

http://medvis.org/datasets/

and

https://www.nlm.nih.gov/research/visible/getting_data.html

For CT images of luggage please have a look at:

http://www.northeastern.edu/alert/transitioning-technology/alert-datasets/

Good luck