Dylan Edwards (asker) Oct 23, 2016:

The adjective 'sumační' is probably used to contrast the X-ray with the scans (CT, MRI) that were done on the patient.

Martin Janda Oct 19, 2016:

Good we are on the same page Dylan :)

Dylan Edwards (asker) Oct 19, 2016:

My hasty research reveals that the term 'summation X-ray' is sometimes used - but not very often.

It's possible to find explanations on these lines:
"The conventional radiograph is a two-dimensional summation image that is dependent on variable absorption of X-rays by different tissues for its inherent contrast."

"Summation shadows
o This results when parts of a patient or an object in different planes are superimposed
o The result is a summation image representing the degree of X-Ray absorption by all the superimposed objects"

Sounds like a traditional X-ray to me!