Clinical Application Of Large Bore CT Simulation in Radiation Oncology

Purpose:To discuss the clinical applying value of large bore CT simulation in Radiation Oncology.Materials and methods:12 NPC patients and 12 breast cancer patients are simulated by using large bore CT and planed,respectively.The precise verification of isocenter treated:all isocenters treated are secondly scaned with 1.25 cm slice thickness and compared with isocenter planed.The deviations between isocenter treated and isocenter planed in X axis(right left direction),Y axis(superior inferior direction),Z axis(anterior posterior direction)were dx,dy,dz,respectively.Then the distant deviations(Di) between isocenter treated and isocenter planed are calculated.The accuracy verification of isocenter treated:Two orthogonal portal images were taken by EPID,All Portal images were registered automatically into the digitally reconstructed radiography(DRR) Then the deviations between isocenter treated and isocenter planed were calculated in X axis,Y axis,Z axis.Results:12 NPC patients and 12 breast cancer patients are simulated in an optimal treatment position.The precise verification of isocenter treated:the distant deviation(Di)of NPC patients between isocenter treated and isocenter planed is 1.7 mm.the distant deviation(Di)of breast cancer patients between isocenter treated and isocenter planed is 2.7 mm.The accuracy verification of isocenter treated:the deviations of NPC patients between isocenter treated and isocenter planed in X axis,Y axis,Z axis are 0 mm,0.4 mm,-0.4 m,respectively.the deviations of breastcancer patients between isocenter treated and isocenter planed in X axis,Y axis,Z axis are 2.0 mm,2.1 mm,-0.4 mm,respectively.Conclusion:Large bore CT simulation not only can satisfy to scan in an optimal treatment position,but also is accuracy.So it can fully satisfy to develop 3D-CRT and the IMRT radiotherapy.