In years past, larger planning target volume (PTV) margins were used to compensate for localization errors during treatment.
The single most important area of innovation in clinical practice is the reduction of the planning target volume margins around the location.
Sensus Healthcare is a manufacturer and distributor of this device With a compact 30”x30” footprint, the mobile unit delivers a precise and calibrated dose of SRT that penetrates only five millimeters below the skin’s surface—making it one of the safest and most effective alternative cancer treatments available.
Unlike more powerful radiotherapy devices, the SRT-100™ carefully destroys malignant skin cancer cells while preserving healthy tissue.
[8] The localization information provided through IGRT approaches can also be used to facilitate robust treatment planning strategies and enable patient modelling, which is beyond the scope of this article.
[citation needed] In general, at the time of 'planning' (whether a clinical mark up or a full simulation) the intended area for treatment is outlined by the radiation oncologist.
The purpose of the ink marks was to align and position the patient daily for treatment to improve reproducibility of field placement.
From the early days of radiation therapy, X-rays or gamma rays were used to develop large format radiographic films for inspection.
Usage of an orthogonal set-up of two radiographic axes is common, to provide means for highly accurate patient position verification.
CT produces a volume of data, which can be manipulated, through a process known as windowing, in order to demonstrate various structures based on their ability to attenuate and prevent transmission of the incident X-ray beam.
[8] Cone-beam computed tomography (CBCT) based image guided systems have been integrated with medical linear accelerators to great success.
With improvements in flat-panel technology, CBCT has been able to provide volumetric imaging, and allows for radiographic or fluoroscopic monitoring throughout the treatment process.
[citation needed] Optical tracking entails the use of a camera to relay positional information of objects within its inherent coordinate system by means of a subset of the electromagnetic spectrum of wavelengths spanning ultra-violet, visible, and infrared light.
Optical navigation has been in use for the last 10 years within image-guided surgery (neurosurgery, ENT, and orthopaedic) and has increased in prevalence within radiotherapy to provide real-time feedback through visual cues on graphical user interfaces (GUIs).
For the latter, a method of calibration is used to align the camera's native coordinate system with that of the isocentric reference frame of the radiation treatment delivery room.
Optically tracked tools are then used to identify the positions of patient reference set-up points and these are compared to their location within the planning CT coordinate system.
The first clinically active MRI-guided radiation therapy machine, the ViewRay device, was installed in St. Louis, MO, at the Alvin J. Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine.
While not IGRT per se, electromagnetic transponder systems seek to serve exactly the same clinical function as CBCT or kV X-ray, yet provide for more temporally continuous analysis of setup error analogous to that of the optical tracking strategies.
Often, a patient will receive corrections to their treatment via on-line strategies during their first radiation session, and physicians make subsequent adjustments off-line during check film rounds.
[4] The On-line strategy makes adjustment to patient and beam position during the treatment process, based on continuously updated information throughout the procedure.