Michael Ljungberg is a Professor at Medical Radiation Physics, Lund, Lund University, Sweden. He started his research in the Monte Carlo field in 1983 through a project involving a simulation of whole-body counters but later changed the focus to more general applications in nuclear medicine imaging and SPECT. Parallel to his development of the Monte Carlo code, SIMIND, he began working in 1985 with quantitative SPECT and problems related to attenuation and scatter. After earning his PhD in 1990, he received a research assistant position that allowed him to continue developing SIMIND for quantitative SPECT applications and to establish successful collaborations with international research groups. At this time, the SIMIND program became used world-wide. Dr. Ljungberg became an associate professor in 1994 and, in 2005, after working clinically as a nuclear medicine medical physicist, received a full professorship in the Science Faculty at Lund University. He became the Head of the Department of Medical Radiation Physics at Lund in 2013 and a full professor in the Medical Faculty in 2015. Aside from the development of SIMIND – including new camera systems such as CZT detectors – his research includes an extensive project in oncological nuclear medicine. In this project, he and colleagues developed dosimetry methods based on quantitative SPECT, Monte Carlo absorbed-dose calculations, and methods for accurate 3D dose planning for internal radionuclide therapy. Lately, his work has focused on implementing Monte Carlo–based image reconstruction in SIMIND. He is also involved in the undergraduate education of medical physicists and bio-medical engineers and supervises MSc and PhD students. In 2012, Professor Ljungberg became a member of the European Association of Nuclear Medicines task group on Dosimetry and served that association for six years. He has published over a hundred original papers, 18 conference proceedings, 18 books and book chapters, and 14 peer-reviewed papers.