ABSTRACT
The rationale for in vivo dose measurements is to provide an accurate and effective independent dose verification of a radiotherapy treatment procedure starting from treatment planning to treatment delivery. Many 2D and semi-3D devices are used for pretreatment patient-specific quality assurance (QA). These instruments are able to detect errors in the transfer of a plan from the treatment planning system to the accelerator, in the dose calculation, and in the delivery of the beams. Briefly, fluence or dose comparisons can be made at the Electronic portal imaging device (EPID) level or in the patient/phantom. Due to variation in anatomy during the course of radiotherapy, the dose actually delivered to a patient may deviate considerably from the planned dose distribution. Several 2D and 3D EPID-based in vivo dose verification methods have been developed during the past decade. The correlation of 3D dose verification with 3D in-room imaging will therefore become more important in the future.
