Pain injections
None of the codes you are asking about get an ASA assigned to them. These are procedure codes billed by units and not time like the anesthesia codes, which do get the ASA assigned to them.
In certain circumstances they can have a modifier. If a resident is participating and this is a teaching environment it could get a GC modifier if you are billing Medicare or some other insurance that requires it. You would want to check your NCCI edits and it will tell you if a modifier is allowed to the code you using it with.
If you read the guidelines in the CPT book (pg 399 of AMA CPT 2017) it states 64479-64487, 64490-64495 are unilateral procedures. So you would use the LT or RT and 50 if it is bilateral. 64479-64484 include imaging guidance so you can not bill separately for that. Pg 401 tells you about 64490-64494... you do not use the LT or RT but you do use the 50 modifier if it was done bilaterally. Pg 404 give you info on 64620-64636. 64633-64636 would get the 50 modifier if done bilaterally.
Hope that helps... new to coding myself... My best references are CMS, AAPC, SuperCoder and the CPT book itself.
ps... almost forgot the modifier 51. some payers require it on procedure codes after the primary procedure. All of the modifier information is on page 727 Appendix A.