Joseph qualified in medicine from Imperial College London, and following early training years in London and the South East, he worked for Medecins sans Frontieres for 2 years in Darfur, Sudan and India. He underwent radiology training at Kings College Hospital, London and Auckland City Hospital, New Zealand before completing an MD Research with Imperial College London under Professor David Hansell at the Royal Brompton Hospital in 2016.

His primary research interest has been in the use of computer tools to quantify lung damage. He was awarded a 5-year Wellcome Trust Clinical Research Career Development Fellowship in 2018 at University College London, to evaluate the role of computer analysis of CT imaging to detect damage in lung cancer screening populations. Other research interests, based at the Centre for Medical Image Computing at University College London relate to the use of computer-analysis of CT imaging in fibrosing lung diseases and airways diseases. He has co-authored over 75 papers, won national and international awards for his work and was awarded the 2017 best thesis prize by the National Heart and Lung Institute.

He is the Research lead for the British Society of Thoracic Imaging and will be appointed as the Roentgen Professor for the year 2021 by the Royal College of Radiologists.