I agree with Charm and the others above, your life, your decisions. My issues started with an ear ache. It wouldn't go away and I wouldn't stop looking for an answer. Then, all of a sudden I had a sore open up under my tongue and it explained the ear ache. Referred pain from the tumor. Even then brush biopsies showed negative. Not trying to scare you but if a PET scan makes you feel more comfortable then nobody should deny your request.
Best Wishes,
Steve

SCC right side BOT/FOM; DX 1-25-06; Neck dissection/25% of tongue removed 2-17-06. Stage 2 Recurrence 7-06: IMRTX35 & 3X Cisplatin ended 10-18-06. Tumor found 03/18/13; Partial Glossectomy 03/28/13 left lateral tongue. Nov. 2014; headaches,lump on left side of throat. Radical Neck Dissection 12-17-14; Tumor into nerves/jugular; Surgery successful, IMRTX30 & 7X Erbotux. Scan 06-03-15; NED! 06-02-16; Mets to left Humerus bone and lesion on lungs-here We go again! Never, Ever Give Up!

**** PASSED AWAY 10/8/16 ****