Dosimetric evaluation of VMAT and IMRT (SS/SW) treatment in Simultaneous Integrated Boost (SIB) plans for prostate cancer in Cheikh Zaid Hospital Oncology (Morocco)

Abstract

Author(s): Rachid Errifai*, Siham Bouaouad, B.K. El Gueddari, Abdelaali Rahmouni and Abdelouahed Chetaine

Radiotherapy treats cancer by using ionising radiations. Over the last few years, it has evolved a lot and some very innovative techniques have appeared. We have chosen to compare these techniques which are: Intensity Modulated Radiation Therapy (IMRT); Volumetric Modulated Arc Therapy (VMAT). The treatment plans of 10 patients were compared and treated with Intensity Modulated Radiation Therapy (IMRT) Step and Shoot (SS), Sliding Window (SW), and VMAT (6MV X-ray beam). Three target volumes were used: PTV 76, PTV 62.7, and PTV 57. The organs at risk delineated were the rectum, the bladder, small intestine. The dose was delivered once a day, five days a week and in 38 sessions in integrated boost (Simultaneous Integrated Boost) (SIB), aiming to deliver the prescribed dose to the tumour volume while respecting the dose constraints in the organs at risk and minimizing their degree of toxicity. Similar results were found for target volume coverage (Dmax). VMAT seems to be the best of these techniques because it is the best at sparing organs at risk. IMRT has almost the same results, but VMAT is much faster. Finally, there was no statistically significant difference between the different techniques. All these results confirm the conformational capacities of these innovative techniques, from a dosimetric and above all clinical point of view as well as their ability to cover the target volumes while largely respecting the constraints on organs at risk.

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