Implant Patient with History of Hodgkin’s Lymphoma: Precautions?

Dr. H. asks:
I have a female patient in her early 50’s with a history of Hodgkin’s Lymphoma treated with radiotherapy more than 40 years ago over the head & neck area, which resulted in halted development of her roots. Three months ago I had to extract her mandibular left canine, first premolar and first molar [#30, 28, 27] as they developed non-restorable caries. The sites healed uneventfully without any complications. Post- operative healing was uneventful without any complications. Now the patient is interested in having 2 dental implants to restore this area. My question is there any risk of osteoradionecrosis (ORN)? Any special precautions that I should take prior to implant surgery?