Study the setup errors by CBCT in radiotherapy with two different immobilization techniques for thoracic and abdominal tumors / 中华放射肿瘤学杂志

ABSTRACT

Objective To study the set-up errors by CBCT in IMRT with two different immobilization techniques for thoracic and abdominal tumors.Methods Sixty patients with thoracic and abdominal tumor were included in this study and separated into study group and the control group.The study group were immobilized with carbon fiber holder,vacuum bag and thermoplastic mask.The control group were immobilized with carbon fiber holder and thermoplastic mask.CBCT scan and auto-match online were regularly performed before the treatment.The setup of left-right(x),superior-inferior(y),anterior-posterior (z) were received.The value of the Mptv was calculated,meanwhile.The grouped t-test of was carried out between these two methods.Results The shift errors in x-,y-,z-dimension of the study group were (0.32 ± 2.58) mm,(-0.40 ± 3.89) mm,(-0.75 ± 2.43) mm.The Mrrv were 5.60 mm,6.08 mm,6.32 mm.The translation set-up errors in x-,y-,z-dimension of the control group were(0.62 ±3.60),(2.44 ± 4.93),(0.66 ±2.85) mm,respectively.The MPrv were 8.07,10.63,6.90 mm,respectively.The t-test value were t =-0.78,-5.11,-4.22,P =0.440,0.000,0.000,respectively.Conclusions The immobilization techniques with carbon fiber holder,vacuum bag and thermoplastic mask would be better than the techniques without the vacuum bag in reducing the setup errors.