3D printed plastics for beam modulation in proton therapy

Abstract

Two 3D printing methods, fused filament fabrication (FFF) and PolyJet™ (PJ) were investigated for suitability in clinical proton therapy (PT) energy modulation. Measurements of printing precision, printed density and mean stopping power are presented. FFF is found to be accurate to 0.1 mm, to contain a void fraction of 13% due to air pockets and to have a mean stopping power dependent on geometry. PJ was found to print accurate to 0.05 mm, with a material density and mean stopping power consistent with solid poly(methyl methacrylate) (PMMA). Both FFF and PJ were found to print significant, sporadic defects associated with sharp edges on the order of 0.2 mm. Site standard PT modulator wheels were printed using both methods. Measured depth-dose profiles with a 74 MeV beam show poor agreement between PMMA and printed FFF wheels. PJ printed wheel depth-dose agreed with PMMA within 1% of treatment dose except for a distal falloff discrepancy of 0.5 mm.

3D printing technology will eventually eliminate the need of purchasing commercial phantoms for clinical medical physics QA procedures

“…Cooling can cause contraction, which may cause the FDM 3D printed object to warp. For charged particle radiation beams especially, this can negatively impact the performance of the 3D printed device or phantom . Therefore, QC of the manufacturing process will need to be performed by 3D printing staff or clinicians whereas for commercial phantoms, QC is performed by the vendor and verified by the clinicians.…”

Intrapatient study comparing 3D printed bolus versus standard vinyl gel sheet bolus for postmastectomy chest wall radiation therapy

“…There is growing interest in the application of 3-dimensional (3D) printing to the radiation therapy process, [9][10][11][12][13][14][15][16][17][18][19][20][21] and a natural application of this developing technology is the generation of treatment accessories based on computed tomography (CT) image data. Although the majority of studies to date focus on phantom experiments or characterize the dosimetric properties of printable media, 19,[21][22][23][24] few studies have demonstrated the utility of 3D printed bolus in application to actual patient treatment. For instance, in a series with 11 patients receiving treatment for nonmelanoma skin cancer, Canters et al 9 created bolus by 3D printing a shell used as a mold and filled with silicone rubber.…”

Technical Note: Manufacturing of a realistic mouse phantom for dosimetry of radiobiology experiments

“…One means of reliably fabricating highly customizable and specialized phantom geometries has emerged via 3D printing, a cost‐effective form of additive manufacturing. Various 3D printing modalities have previously been evaluated for use in the context of radiotherapy and diagnostic imaging . Of these, material jetting is found to provide a number of desirable properties well suited to the development of a small, detailed, anatomically accurate and highly uniform small animal phantom.…”

“…Various 3D printing modalities have previously been evaluated for use in the context of radiotherapy and diagnostic imaging. [4][5][6] Of these, material jetting is found to provide a number of desirable properties well suited to the development of a small, detailed, anatomically accurate and highly uniform small animal phantom. Specifically, the technology features the highest available feature resolution and the ability to print a solid model using multiple materials within a single job.…”