AlignRT (Vision RT) is a system for monitoring the position and movement of a person during set‑up for, and treatment with, stereotactic radiosurgery (SRS). SRS and stereotactic radiotherapy (SRT) are accurate forms of radiation treatment that can be used to treat small secondary brain tumours. SRT delivers the radiation in a number of daily doses, called fractions. In SRS, the radiation is delivered in a single fraction.
AlignRT uses 3 video cameras to monitor the person's position with accuracy to within 1 mm or 1‑degree rotation during radiotherapy. AlignRT communicates with the linear accelerator (LINAC) delivering the radiation, and instructs it to stop the radiation beam if the person moves. This prevents radiation from being delivered to neighbouring tissue and organs, which can lead to unwanted side effects and incomplete treatment of the target tumour. AlignRT can also be used in the treatment of other cancers, but these are beyond the scope of this briefing.
AlignRT consists of 3 wall- or ceiling-mounted video camera projector pods, each including a red-light surface projector. During use, the person lies with their head in a custom-made head support to minimise movement. Visible red light in a random pattern is projected from each camera pod onto the person's head, and the resultant light is detected by 2 sensors in each pod. The AlignRT software generates a real-time 3D surface image of the person. This real-time image is aligned with an image of the bony anatomy of the person's head that has been taken from an earlier CT scan, which is done to image the tumour and its location to plan treatment. By aligning the real-time and treatment-planning images, clinicians can predict the tumour location.
If needed, the person's position can be adjusted using the AlignRT interface with the automatic treatment couch control system. Internal imaging is performed using the linear accelerator to confirm the tumour location and SRS treatment can then begin.
If AlignRT detects any movement during treatment it instructs the linear accelerator to stop the radiation beam, or prompt the users to manually stop treatment. This allows the person to be moved back into the correct position before treatment can start again.
AlignRT integrates with the radiotherapy system. It is also marketed as part of the Varian EDGE radiosurgery system (Varian Medical Systems), when it is called the optical surface monitoring system (OSMS).
AlignRT uses video cameras to track movement during treatment, as an alternative to more invasive and potentially positioning systems such as bite plates, or external fixation devices such as full-face masks or frames, which may need to be surgically placed using screws or pins. In addition, AlignRT uses a custom-made head support which, unlike some other devices, does not cover the face, and is designed to be more comfortable and reduce anxiety and feelings of claustrophobia. AlignRT also allows the person to be monitored throughout the treatment, which may not be possible with other positioning techniques.
Using AlignRT allows treatment-planning CT scans to be done and the custom head support to be made several days before treatment. In monitoring systems that use a surgically fixed external frame, the whole treatment cycle of dosimetry planning, clinical treatment planning, sign off and treatment has to be completed within 1 session once the frame is in place. This is because alignment to the CT scans is lost once the frame is removed, and treatment planning would have to be repeated. This can place pressure on the staff and treatment suite workflow, as well as being distressing and time-consuming for the person being treated. Because AlignRT can be used over several sessions using the same head support, it can be used for SRT as well as SRS.
Microsurgery, with or without whole-brain radiotherapy, is usually offered for large tumours in accessible positions in the brain.
People in whom SRS or SRT are suitable are defined in the NHS England's clinical commissioning policy on stereotactic radiosurgery as having good performance status, controllable systemic disease and low-volume metastatic disease. SRS can be considered in a small subset of patients when there is evidence of its effectiveness, and when conventional surgery is contraindicated or the risk of functional disability would be increased through surgery. Treatment is planned for each person by a multidisciplinary team. AlignRT would be used as part of delivering SRS or SRT for people who are suitable for this treatment.
Current methods of positioning involve the standard radiotherapy-planning CT scan and subsequent patient alignment using X‑ray imaging in several planes and adjustment of the patient couch. The patient's head is held in position using an appropriate method. Other systems such as Exactrac, CyberKnife and Gamma Knife use dedicated X‑ray or additional radiation sources.
The AlignRT system is used in the NHS for guiding breast cancer radiosurgery.
NICE is aware of the following CE‑marked devices that appear to fulfil a similar function to AlignRT:
Catalyst (C‑Rad) – uses a similar optical system to position the person.
Bite-block (Zmed/Varian) – uses infrared tracking; the person must hold a reflective unit between their teeth.
Exactrac (Brainlab) – uses X‑ray tracking.
Gamma Knife (Elekta) – uses X‑ray tracking; the Gamma Knife dedicated system must be installed for it to be used. This system also needs a head-frame screwed to the person's skull, or additional integrated stereotactic cone beam CT for it to be used as a mask system.
CyberKnife (Accuray) – uses X‑ray; the CyberKnife dedicated system must be installed.
AlignRT would be used in patients with brain tumours in whom SRS is suitable. SRS would be done in specialist tertiary centres with linear accelerator (LINAC) facilities. It would be used by a trained therapy radiographer.
The list price of AlignRT is £250,000 (excluding VAT). The annual service charge is £25,000. Assuming a 10‑year lifespan, the total cost of ownership would be £50,000 per year. If 50 people were treated for brain tumours per year, the cost of AlignRT would be £1,000 per treatment.
AlignRT can also be used while treating other more common cancers, including breast cancer. If purchased by a centre that used it to treat a range of cancers, then this may reduce the cost per treatment proportionally. Other indications are outside the scope of this briefing.
Training is provided by the company and is included in the cost of AlignRT. Training consists of 2.5 days of training at the company's office for a therapeutic radiographer and physicist, with the intention that these 2 staff then train the rest of the department. A representative from the company then visits the site for 2 days to put the device into use.
The company estimates that the cost of comparable technologies (including installation) would be £600,000 to £3 million, depending on the choice of system. Annual service charges would range from £50,000 to £250,000 per year.
Based on the company's assumptions of comparator lifespan and throughput, this would equate to at least £2,200 per treatment.
Adopting AlignRT is not expected to have any resource consequences, beyond the cost of the equipment, or to need any changes in facilities or infrastructure. The company has stated AlignRT is compatible with all common LINAC systems used in the UK.
If the same number or more people are treated in daily schedules as they are now, using AlignRT could improve workflows at an SRS/SRT unit. AlignRT can allow the treatment of multiple brain tumours in a single treatment plan, potentially reducing treatment time. This capability is not available with some other devices. AlignRT can be used with existing treatment technologies and treatment-planning software, unlike some other solutions that need a new treatment-planning platform to be commissioned and training on it provided. The technology is only likely to provide the savings in circumstances where investment in new or replacement systems are being contemplated, because of the high upfront costs of procuring the technology.