When we refer to the safety of children in radiology services, the first thing that comes to mind, or at least should be, is the associated risk of cancer throughout the life of these patients derived from the exposure to ionizing radiation. This book, without intending to delve into the genetic and molecular bases of this pernicious effect, aims to address in a concise and simple way the reason for this potential risk without avoiding the controversies that still exist in this regard. Likewise, also in a concise but rigorous way, we show how the safety of the pediatric patient in said hospital environment is a much broader and more complex field of study and work. Within this complexity we include the adequate management of the risks associated with the use of contrast media, the transfer of patients from the different neonatal units, the sedation required in magnetic resonance studies and exposure to magnetic fields that this last technique of image generates.