Development of compact collimation device for novel scanning beam low-energy intraoperative radiation therapy (SBIORT) system for pancreatic cancer

Intraoperative radiation therapy (IORT) involves delivering high doses of radiation directly to tumors while sparing healthy tissues in a surgical setting. Current IORT systems lack the capability to deliver conformal radiation therapy. To overcome the limitations of non-conformal radiation therapy a collimation system is needed to conform the radiation beam to the shape of the tumor. This work presents the development of a compact collimator design intended for a scanning beam IORT (SBIORT) system. The SBIORT collimator design enables the delivery of variable square doses to the targeted region within the surgical cavity. The SBIORT collimator has a compact circular footprint of 66 mm diameter and 10 mm thickness, with a maximum aperture of 20 mm. SBIORT collimator was prototyped to validate the design in positional accuracy and dosimetry experiments. Accuracy of the collimator leaf position was ±0.25mm at a 95% confidence interval. Dosimetric evaluation revealed the collimator to have a penumbra of 1.9 mm with a leaf transmission of 0.5%. The results support the feasibility of implementing the compact SBIORT collimator design in IORT.