X-Ray Important Facts

- A decrease in KvP would result in an increase in image contrast.

- In order to create a significant difference in the optical density of a film there must be at least a 15% change in the mAs for each exposure.

- Reducing the mAs of an image will make it significantly lighter. Increased mAs would result in a darker image.

- It takes at least a 4% change in KvP to make a noticeable change in image contrast.

- You would have to change mAs 50% to equal the change of a 15% KvP alteration.

- It is more efficient to control the density of a film with time of exposure, as compared to the large changes necessary with mAs.

- If KvP goes up 15%, then the mA will have to go down 50%.

- If KvP goes down 15%, then the mA will have to go up 100%.

- Occupational exposure is measured in “Sieverts”

- Patient exposure is measured in “Rad’s”

- For a 70 KvP exposure you can expect approx. 3-6 milliroentgens/mAs

- If you decrease the focal distance by 50% you need to decrease the mAs by ¼

- Increase the focal distance by 50% and subsequently double the mAs.

Category: Radiology Notes