I understand your concern.
A large calculus measuring 20mm in the left PUJ is definitely an indication for PCNL (Percutanous Nephrolithotomy. If the PCNL cannot be done, then you may have to go in for an open surgery.
The multiple calculi measuring 14 to 18mm in the mid and lower calyceal region can be removed using Ureteroscopic retrieval of the stone or the basketing technique. However, the calculi are quite large for this also.
So, my opinion is that laser
may not be effective in you. You may require an open surgery for the stones.
The decision lies with the operating urologist
and the patient.
Hope I have been of help to you.