Dosimetric evaluation of respiratory gated volumetric modulated arc therapy for lung stereotactic body radiation therapy using 3D printing technology

Abstract

PurposeThis study aimed to evaluate the dosimetric accuracy of respiratory gated volumetric modulated arc therapy (VMAT) for lung stereotactic body radiation therapy (SBRT) under simulation conditions similar to the actual clinical situation using patient-specific lung phantoms and realistic target movements.MethodsSix heterogeneous lung phantoms were fabricated using a 3D-printer (3DISON, ROKIT, Seoul, Korea) to be dosimetrically equivalent to actual target regions of lung SBRT cases treated via gated VMAT. They were designed to move realistically via a motion device (QUASAR, Modus Medical Devices, Canada). Using the lung phantoms and a homogeneous phantom (model 500–3315, Modus Medical Devices), film dosimetry was performed with and without respiratory gating for VMAT delivery (TrueBeam STx; Varian Medical Systems, Palo Alto, CA, USA). The measured results were analyzed with the gamma passing rates (GPRs) of 2%/1 mm criteria, by comparing with the calculated dose via the AXB and AAA algorithms of the Eclipse Treatment Planning System (version 10.0.28; Varian Medical Systems).ResultsGPRs were greater than the acceptance criteria 80% for all film measurements with the stationary and homogeneous phantoms in conventional QAs. Regardless of the heterogeneity of phantoms, there were no significant differences (p > 0.05) in GPRs obtained with and without target motions; the statistical significance (p = 0.031) was presented between both algorithms under the utilization of heterogeneous phantoms.ConclusionsDosimetric verification with heterogeneous patient-specific lung phantoms could be successfully implemented as the evaluation method for gated VMAT delivery. In addition, it could be dosimetrically confirmed that the AXB algorithm improved the dose calculation accuracy under patient-specific simulations using 3D printed lung phantoms.

A customizable anthropomorphic phantom for dosimetric verification of 3D‐printed lung, tissue, and bone density materials

“…40 More complex lung scenarios are to be investigated to systematically study behaviors of different deformable image registration algorithms, potentially beneficial for future clinical trial audits utilizing similar advanced imaging tools for multi-modality target delineation and deformable dose accumulation. 15,17,41,42 This application can be extended toward the 3D printing of realistic phantoms with a mixture of solid and deformable walls, filled with deformable carrageenan-based materials for the enhanced physical emulation of organ deformation. 20 Different tissue type inserts can be made within an anthropomorphic setting to validate dual-energy CT contrast resolution of the various tissue types, which is important for particle therapy dose calculation modeling as mapping the stopping power ratio for different tissue types is one of the key sources in beam range uncertainty.…”

“…Complex radiotherapy scenarios can be also emulated for validation purposes, which will be beneficial to design comprehensive imaging and dosimetry audits such as the emulation of metal implants in phantoms 40 . More complex lung scenarios are to be investigated to systematically study behaviors of different deformable image registration algorithms, potentially beneficial for future clinical trial audits utilizing similar advanced imaging tools for multi‐modality target delineation and deformable dose accumulation 15,17,41,42 . This application can be extended toward the 3D printing of realistic phantoms with a mixture of solid and deformable walls, filled with deformable carrageenan‐based materials for the enhanced physical emulation of organ deformation 20 .…”

“…14 The 3D-printed lung rod insert consists of a patient-specific lesion and was utilized with a motion phantom to verify dose distributions in a more realistic respiratory condition. This concept was found to be clinically feasible for assessing the accuracy of a lung tracking system 15 and the investigation of various patientspecific lung lesion sizes and positions comparing dosemeasuring algorithms using stereotactic ablative body radiotherapy (SABR) for 3D conformal 16 or volumetric modulated arc therapy (VMAT) 17,18 treatment planning. Another area of research involves using non-printable materials, known as tissue substitutes, combined with 3D printing materials to enhance the emulation of tissue HU in addition to a mobile tumor, allowing a more realistic replication of lung density and deformation.…”

Additive manufacturing (3D printing) in superficial brachytherapy

“…AM is not new to radiation therapy nor limited to BT. Bolus [26], phantoms [27], immobilizers [28], and field-shaping devices [29] are a few of the other areas in RT, where AM technology has been incorporated. AM applicators are an attractive solution, as they enable almost exact replica of a patient's surface as well as fully customizable catheter tracks.…”

Patient-Specific Quality Assurance Using a 3D-Printed Chest Phantom for Intraoperative Radiotherapy in Breast Cancer

“…There have been attempts to manufacture customized objects incorporating 3D printing technology into various applications of radiation therapy (11)(12)(13)(14)(15)(16)(17). In this manner, to overcome the limitations of IORT's PSQA, we ensure the stability of IORT by creating a PSQA phantom via 3D printing.…”