MEDRADSC 2F03 Lecture Notes - Lecture 6: Collimator, Radiography, Axial Tilt

• School: McMaster University
• Department: Medical Radiation Sciences
• Course: MEDRADSC 2F03
• Professor: Lumsden

Document Summary

Very small zone of x-ray production on anode in x-ray tube. The actual x-ray source, the area of the target from which x-rays are emitted. Smaller focal spot size: good: better for the spatial resolution of the image (more detail), minimizes geometric unsharpness the heati(cid:374)g of the target is (cid:272)o(cid:374)(cid:272)e(cid:374)trated o(cid:374)to a s(cid:373)aller area a(cid:374)d does(cid:374)"t allow as (cid:373)u(cid:272)h heat dissipatio(cid:374) Larger focal spot size: good: for reducing concentration of heat loading on anode target. Sufficiently small to behave as an approximate point source of radiation has a certain thickness. Simultaneously improves spatial resolution and heat capacity. Collimator restricts the size of the radiation, needs to be appropriate to the part. The closer the hugging of the central ray, the less divergence there is. Image not represented accurately, loss of detail: distortion. Anytime we angle the cr, we create distortion. Less distortion with a higher sid, want to minimize oid (flat against detector is best)