SU‐FF‐T‐430: Two Beam Segment‐Based Intensity Modulated Radiation Therapy for Solid Tumours of the Brain

We present a novel segment‐based intensity‐modulated radiation therapy (s‐IMRT) technique that utilizes a single lateral and single vertex beam for the treatment of solid braintumours that eliminates the necessity of employing physical wedges traditionally employed for such treatments. The two beam s‐IMRT method potentially allows for streamlined treatment planning and improved dose calculation accuracy while minimizing quality assurance workload compared to conventional multi‐beam IMRTtreatments. The beam segments for lateral beams were generated based on the isodose distributions of a 100% weighted vertex beam while the vertex beam were created from the isodose distribution of a 100% weighted lateral beam. Segment weight optimization was performed using the inverse planning tool of the Pinnacle 7.6 treatment planning software. Segment‐IMRT plans were compared to “best‐case” wedge‐based plans to evaluate differences in dose uniformity, target coverage, and normal tissue sparing. Five patients with solid tumours of the brain were planned for radiation therapy. Overall, the s‐IMRT approach resulted in similar dose distributions as the wedge‐based plans. However, the overall treatment planning time was significantly reduced using s‐IMRT (∼ 60 min. compared to ∼ 150 min.). With the addition of script‐based automated segment generation and optimized inverse planning parameters it is believed that treatment planning time may be further reduced to ∼ 30 min. Furthermore, it is anticipated that the elimination of physical wedges will expedite patient set‐up time for treatments while improving dosimetric accuracy.