The novel radiation therapy unit described here is designed for fast and cost effective adaptive intensity modulated radiation therapy. Today, efficient tumor diagnostics based on PET-CT imaging, using tumor specific tracers, allow accurate delineation of the local regional tumor spread, both before the start of the treatment and during the first two weeks of treatment to quantify the treatment response. This type of image allows monitoring of the local radiation responsiveness of the tumor in 3D. Thus, the total delivered dose distribution can be optimally controlled by adapting the initial biologically optimized treatment plan based on the integrated dose delivery and biological response during fractionated radiation therapy. The biological adaptation can be based on the initial tumor spread, and also the observed in vivo tumor responsiveness to increase both the quality and safety of the treatment.
Fast high energy pencil beam scanning offers a possibility for intensity modulation in combination with online treatment verification by combining PET and radiotherapeutic-computed tomography (PET-RCT). It may even be possible to image the substantial quasi prompt positron annihilation induced between pulses through pair production by high energy photons in addition to the positrons generated by photonuclear reactions, to get a photon dose related signal that is almost independent on the vascular blood flow in the patient.
The fast narrow photon and electron pencil beam scanning system integrated with the new fast gea electron multiplier (GEM) portal imager and laser camer (LC) may also in the future allow improved patient set-up as well as dynamic locking on a moving tumor in real time. Interestingly, the beam scanning system can be auto-calibrated and use real time dosimetric verification with the segmented high-resolution transmission monitor. The new therapy system will thus be an ideal tool for true 3D IMRT.