Radiolgy Test

RadMatic · Guest

Does incresing KVP have an effect on contrast? If so, what is that effect?

MurphyMobile · Moderator Joined: 26 Aug 2006 Posts: 149 Location: WNC

High kVp decreases contrast - more shades of gray. Good for Chests.

Low kVp increases contrast - more black and white. Good for orthopedic
work.

I have worked in a local hospital in WNC that insisted on using high
kVp for portable chests at 40" TID.
Ex.: 90 kVp @ 1.5 mAs at 40 " TID supine (portable in ICU).

I would use 80 kVp @ 5 mAs at 72" TID upright or semi-upright and collimated to the lungs

Despite what ALARA states, it is far better to get one excellent image than
repeat. I had a difficult time explaining to the youger techs that 90 kvp will
burn out lung tissue PERIOD.

This is what makes a technologist good. Being able to decides before making an exposure if your technique is suitiable for the patient.

With AEC with the body parts listed on the equipment is not always the
answer. Manual technique has its advantages.

MM Cool

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steve white · Joined: 09 Apr 2010 Posts: 6 Location: kernersville nc

There is a great deal of variation in practice in techniques in portable chests. I am working in a hospiital in NC where the technique for port chest is non grid 90 kVp 5 -6.4 mAs 60 SID w/ Grid 110 kVp and 16-25 mAs 40-45 SID This provides pretty good results.