FLEXPOINT® Crosshair module used for Radiation Oncology

06 Jul 2021

Volumetric modulated arc therapy (VMAT) is an advanced radiotherapy technique that uses arcs of radiation, rather than individual beams used in other types of radiotherapy.  As the machine (called a linear accelerator or linac) moves, it automatically changes the beam shape and treatment dose.  To treat patients using the voluntary breath hold technique, a novel couch mounted laser was designed.

An additional laser is used along with the traditional way of marking the edge of light field to observe the breath hold for tangential treatments.

The FLEXPOINT® 520nm crosshair laser module can be mounted behind the patient to project a crosshair on the patient’s chest allowing the chest wall position (and thereby extent of breath hold) to be visualised on the CCTV camera throughout treatment.

The Active Breathing Coordinator™ (ABC) device is used to reduce the amount your organs move by holding your breath for you.  A study was approved by the Royal Marsden Committee for Clinical Research and The HRA London-Stanmore Research Ethics Committee.  This study demonstrates that with use of the additional laser to verify chest wall position, there is no difference between the voluntary breath hold technique and the use of the ABC machine.

ABC is an expensive device costing around £50,000 with disposable mouthpieces costing £150 each.  The HeartSpare system costs less than £500 to produce for the laser module with diffractive optics (crosshair), camera mount with pole, 360°piston ball grip head and battery pack.  This system can easily be reproduced for other radiotherapy departments and adapted to suit the requirements for individual centres.

A detailed article regarding the use of the HeartSpare laser vs the ABC machine was published in Elsevier Clinical and Translational Radiation Oncology journal.

1. Ranger, A. Dunlop, A. Grimwood et al. Clinical and Translational Radiation Oncology 27 (2021) 164-168 https://www.sciencedirect.com/science/article/pii/S2405630821000173

Further information https://www.lasercomponents.com/uk/product/pattern-generators-for-flexpoint-laser-modules/