Abstract
In radiation therapy, a bolus is used to improve dose distribution in superficial tumors; however, commercial boluses lack conformity to patient surface leading to the formation of an air gap between the bolus and patient surface and suboptimal tumor control. The aim of this study was to explore 3D-printing technology for the development of patient-specific conformal 3D-printed devices, which can be used for the radiation treatment of superficial head and neck cancer (HNC). Two 3D boluses (0.5 and 1.0 cm thick) for surface dose build-up and patient-specific 3D phantom were printed based on reconstruction of computed tomography (CT) images of a patient with HNC. The 3D-printed patient-specific phantom indicated good tissue equivalency (HU = −32) and geometric accuracy (DSC = 0.957). Both boluses indicated high conformity to the irregular skin surface with minimal air gaps (0.4–2.1 mm for 0.5 cm bolus and 0.6–2.2 mm for 1.0 cm bolus). The performed dose assessment showed that boluses of both thicknesses have comparable effectiveness, increasing the dose that covers 99% of the target volume by 52% and 26% for single field and intensity modulated fields, respectively, when compared with no bolus case. The performed investigation showed the potential of 3D printing in development of cost effective, patient specific and patient friendly conformal devices for dose verification in radiotherapy.
Highlights
Complex radiotherapy modalities (IMRT, IGRT, VMAT) have gained increased importance in recent years due to their superior survival outcomes with fewer treatment-related side effects as compared to conventional radiotherapy [1,2,3,4]
Placement of such bolus on the patient’s head and neck surface results in the formation of air gaps between the bolus and patient surface, which in turn contribute to surface dose reduction and inhomogeneous dose distributions [11,12,13]; the challenges mentioned above should be taken into account when producing patient-friendly personalized boluses
In order to overcome the skinsparing effect in radiotherapy treatment, the application of 3D-printed bolus/compensating structure was explored in this study
Summary
Complex radiotherapy modalities (IMRT, IGRT, VMAT) have gained increased importance in recent years due to their superior survival outcomes with fewer treatment-related side effects as compared to conventional radiotherapy [1,2,3,4] These high conformal radiotherapy techniques offer complex dose distributions in the target along with a sharp dose gradient, which results in lessening the effect on organs at risk (OAR). The main disadvantage of commercial boluses is the lack of conformity to irregular surface such as the nose, ear and scalp Placement of such bolus on the patient’s head and neck surface results in the formation of air gaps between the bolus and patient surface, which in turn contribute to surface dose reduction and inhomogeneous dose distributions [11,12,13]; the challenges mentioned above should be taken into account when producing patient-friendly personalized boluses
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