John qualified in University College Galway (NUIG) and completed MRCPI, FRCR, FFRRCSI, and an MSc in Radiologic Sciences while initially training at the Mater University Hospital before pursuing further training in Northwick Park Hospital, London UK, San Francisco General Hospital (UCSF), California, Duke University Medical Centre, North Carolina, and the Cleveland Clinic, Ohio USA. He was appointed as Consultant Radiologist to the Mater University Hospital in 1996, and is a Clinical Professor UCD School of Medicine. He was instrumental in establishing the PETCT and Cardiac MR services at the Mater. He is a former Chairman of the Division of Radiology, National Lead for the Irish Radiology Training Programme, and examiner in the Final Fellowship exam, Faculty of Radiologists, RCSI. He has extensive sub specialty training in Cardiac and Thoracic imaging and Intervention and has authored over 70 peer reviewed publications.