ABSTRACT
Patient-specific quality assurance (QA) is generally considered to be a pretreatment verification method using either a measurement-based or a calculation-based technique. The relationship between pretreatment homogeneous phantom measurements and the dose distribution in a more realistic patient geometry with tissue heterogeneities is not unambiguous. Patient-specific QA in a broader sense includes QA of all steps involved in the treatment process of an individual patient, including physician and physicist plan review, therapist chart review, and patient setup verification. Performing in vivo patient dose measurements implies that the radiation dose measured with a detector has to be correlated with the dose in the patient. In vivo dosimetry can therefore be considered as a very suitable method to verify on a day-to-day basis the actual dose delivered to a patient during a radiotherapy treatment course. When an electronic portal imaging device-based dose verification measurement shows an alert, a number of follow-up actions are needed.
