Clinical application of 3D printed bolus with specific density in breast cancer radiotherapy
Objective To investigate the clinical application of 3D printed bolus with specific density in breast cancer radiotherapy,and to evaluate its effects on dose distribution and positioning.Methods Forty post-mastectomy patients undergoing intensity-modulated radiotherapy were randomly enrolled for 3D printed bolus(n=20)and conventional bolus(n=20),and all patients were fixed in the supine position using styrofoam.Conventional positioning was performed based on in-room lasers and body markers,with daily Catalyst HD optical surface monitoring combined with weekly CBCT verification.The absolute dose,patients'skin surface dose,surgical incision,planned field,target area doses(VCTV50Gy,VPTV50Gy)and organs-at-risk doses in patients with different boluses were recorded,and the conformity index and homogeneity index were calculated,and the setup errors using CBCT and Catalyst HD were also analyzed.Results The difference in absolute dose between different boluses was trivial,but the skin surface dose with 3D printed bolus was significantly higher than with conventional bolus[(54.83±0.44)Gyvs(54.43±0.51)Gy,P<0.05].Patients with 3D printed boluses had a higher conformity index than with conventional boluses(0.69±0.04 vs 0.65±0.02).For different boluses,there was no significant difference in VCTV50 Gy,while the VPTV50 Gy and organs-at-risk doses were lower in those with 3D printed bolus than conventional boluses(P<0.05),with heart Vmean of 9.68%±3.24%vs11.43%±3.60%.In patients with 3D printed boluses,both planned field arrangement and surgical incision affected the target doses,and the doses of the target area without an internal breast wrap was greater than those with internal breast wrap(P<0.05).When the field was not wrapped around the internal breast,the surgical incisions only affected VPTV50 Gy,and the VPTV50 Gy was greater with the transverse fusiform incision than with the oblique vertical incision(P<0.05),which were 95.58%±0.51%vs95.44%±0.71%.The optical monitoring accuracies with different boluses differed only in the left-right direction(P<0.05),with(0.08±0.57)cm and(-0.15±0.46)cm for 3D printed and conventional boluses.Conclusion Compared with conventional bolus,3D printed bolus can improve dose distribution and optical monitoring accuracy.The surgical incision and planned field arrangement under 3D-printed bolus would exert effects on target doses.
breast cancer3D printed bolusCatalyst HDdose distribution
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