With programs like reaConverter or similar picture converters it should be possible to convert images saved in Qrt Ray-Tracer format (.qrt) to common JPEG variant. May not always work flawlessly but seems doable.
Convert Qrt Ray-Tracer ray-traced bitmap image to JPEG bitmap image format.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert qrt to jpeg on Windows
A dedicated conversion software
Convert from qrt file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.