Radiation safety, contrast and gadolinium in pain procedures

Distance, time and shielding limit radiation. Contrast matters most where an intravascular injection could injure the cord or brain: without it, postpone high-level transforaminal, upper cervical and sympathetic procedures, and never give gadolinium where subarachnoid spread is possible.

1. Distance is the strongest radiation tool. Exposure follows the inverse square law, so doubling the distance from the scatter source cuts exposure to about one-quarter; scatter at 1 m is roughly 0.1% of the patient's absorbed dose rate ¹².
2. Rank procedures by contrast dependence. The 2022 multisociety advisory says transforaminal injections and selective nerve blocks at L2 and above, atlanto-axial and atlanto-occipital injections, and stellate blocks should be postponed if iodinated contrast is unavailable ³.
3. Lower-risk procedures may proceed. Lumbar interlaminar epidurals and medial branch blocks are lowest importance; transforaminal injections below L2 may proceed without contrast only with a nonparticulate steroid such as dexamethasone ³.
4. Interlaminar epidural without contrast: adjust the injectate. Consider omitting local anesthetic, because a dural breach could cause a high spinal, and use preservative-free steroid in case of intrathecal injection ³.
5. Use ultrasound where it is proven. Some procedures, such as stellate ganglion block under ultrasound by experienced operators, can be done without iodinated contrast ³.
6. Gadolinium is not a neuraxial substitute. Gadolinium-based contrast may be an alternative for some procedures but should be avoided in any neuraxial procedure with risk of subarachnoid injection, such as epidural steroid injections ³.

Intrathecal gadolinium can be catastrophic; never substitute it for iodinated contrast in epidural or other neuraxial injections ³.

• Moving from 0.5 m to 1 m from the scatter source reduces exposure to one-quarter ¹.
• Assistants standing farther from the source receive less exposure than operators ².
• Transforaminal injections at L2 and above carry radiculomedullary artery risk and need contrast ³.
• Do not draw from one contrast vial for multiple patients; only pharmacists may repackage vials, under sterile conditions ³.
• Discuss the risks of proceeding without contrast with the patient beforehand and document it ³.
• Cord injury after transforaminal injection is not confined to L2 and above; cases are documented from L3 to S1 ³.
• Options during a shortage include postponing, proceeding without contrast, using gadolinium where safe, ultrasound techniques, or an alternative treatment ³.
• Staff should keep doses as low as reasonably achievable (ALARA) while still obtaining adequate images ¹.

• Using a particulate steroid for a transforaminal injection done without contrast ³.
• Substituting gadolinium for an epidural steroid injection ³.
• Doing a stellate block without contrast and without ultrasound expertise ³.
• Assuming the operator and assistant receive the same dose regardless of where they stand ².