The most common and most likely answer to this crossword clue is the 10 letter word ULTRASOUND
I've seen this crossword clue in The Times
U
L
T
R
A
S
O
U
N
D
More clues leading to the result ULTRASOUND
Buddy explains!

The straight part
We know that "medical scan" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case medical scan = ultrasound.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ULTRASOUND mean?
ULTRASOUND noun- Sound with a frequency greater than the upper limit of human hearing, which is approximately 20 kilohertz.
- The use of ultrasonic waves for diagnostic or therapeutic purposes.
- To treat with ultrasound.