WE-F-16A-02: Design, Fabrication, and Validation of a 3D-Printed Proton Filter for Range Spreading

Purpose The aim of this work is to describe the clinical implementation of respiratory‐gated spot‐scanning proton therapy (SSPT) for the treatment of thoracic and abdominal moving targets. The experience of our institution is summarized, from initial acceptance and commissioning tests to the development of standard clinical operating procedures for simulation, motion assessment, motion mitigation, treatment planning, and gated SSPT treatment delivery. Materials and methods A custom respiratory gating interface incorporating the Real‐Time Position Management System (RPM, Varian Medical Systems, Inc., Palo Alto, CA, USA) was developed in‐house for our synchrotron‐based delivery system. To assess gating performance, a motion phantom and radiochromic films were used to compare gated vs nongated delivery. Site‐specific treatment planning protocols and conservative motion cutoffs were developed, allowing for free‐breathing (FB), breath‐holding (BH), or phase‐gating (Ph‐G). Room usage efficiency of BH and Ph‐G treatments was retrospectively evaluated using beam delivery data retrieved from our record and verify system and DICOM files from patient‐specific quality assurance (QA) procedures. Results More than 70 patients were treated using active motion management between the launch of our motion mitigation program in October 2015 and the end date of data collection of this study in January 2018. During acceptance procedures, we found that overall system latency is clinically‐suitable for Ph‐G. Regarding room usage efficiency, the average number of energy layers delivered per minute was <10 for Ph‐G, 10‐15 for BH and ≥15 for FB, making Ph‐G the slowest treatment modality. When comparing to continuous delivery measured during pretreatment QA procedures, the median values of BH treatment time were extended from 6.6 to 9.3 min (+48%). Ph‐G treatments were extended from 7.3 to 13.0 min (+82%). Conclusions Active motion management has been crucial to the overall success of our SSPT program. Nevertheless, our conservative approach has come with an efficiency cost that is more noticeable in Ph‐G treatments and should be considered in decision‐making.

Section: Discussionmentioning

confidence: 99%

Clinical implementation of respiratory‐gated spot‐scanning proton therapy: An efficiency analysis of active motion management

Gelover

Deisher

Herman

et al. 2019

“…The material used in this study was ultraviolet curable acrylic plastic. Other proton radiotherapy applications include 3D printed range spreading filter (22) and patient‐specific bolus for proton (23) . Our study focused on the fabrication process and characterizations of 3D‐printed patient electron bolus and proton compensator using FDM and SLS technologies with PLA and polyamide materials, respectively.…”

Section: Introductionmentioning

confidence: 99%

Potential of 3D printing technologies for fabrication of electron bolus and proton compensators

Zou

Fisher²,

Zhang

et al. 2015

In electron and proton radiotherapy, applications of patient‐specific electron bolus or proton compensators during radiation treatments are often necessary to accommodate patient body surface irregularities, tissue inhomogeneity, and variations in PTV depths to achieve desired dose distributions. Emerging 3D printing technologies provide alternative fabrication methods for these bolus and compensators. This study investigated the potential of utilizing 3D printing technologies for the fabrication of the electron bolus and proton compensators. Two printing technologies, fused deposition modeling (FDM) and selective laser sintering (SLS), and two printing materials, PLA and polyamide, were investigated. Samples were printed and characterized with CT scan and under electron and proton beams. In addition, a software package was developed to convert electron bolus and proton compensator designs to printable Standard Tessellation Language file format. A phantom scalp electron bolus was printed with FDM technology with PLA material. The HU of the printed electron bolus was 106.5±15.2. A prostate patient proton compensator was printed with SLS technology and polyamide material with −70.1±8.1 HU. The profiles of the electron bolus and proton compensator were compared with the original designs. The average over all the CT slices of the largest Euclidean distance between the design and the fabricated bolus on each CT slice was found to be 0.84±0.45 mm and for the compensator to be 0.40±0.42 mm. It is recommended that the properties of specific 3D printed objects are understood before being applied to radiotherapy treatments.PACS number: 81.40

“…Users could modify the volume of the VGM (whether proportionally or not) by only changing the size of voxels in the FLUKA user routine file, and simultaneously precheck the 2D as well as 3D viewgraphs of the VGM in Flair. With the development of 3D printing, more and more radiation therapy centers use this technology to materialize the beam-modulated equipment 21,22 or human tissue. 23,24 In our current study, various factors potentially influenced the observed discrepancies across the design→ simulation validation→ 3D printing process for the models.…”

Section: Discussionmentioning

confidence: 99%

A simple method to import CAD mesh format models in FLUKA

Dong

Sheng

Wang

et al. 2023

BackgroundMonte Carlo (MC) code FLUKA possesses widespread usage and accuracy in the simulation of particle beam radiotherapy. However, the conversion from computer‐aided design (CAD) mesh format models to FLUKA readable geometries could not be implemented directly and conveniently. A simple method was required to be developed.PurposeThe present study proposed a simple method to voxelize CAD mesh format files by using a Python‐based script and establishing geometric models in FLUKA.MethodsFive geometric models including cube, sphere, cone, ridge filter (RGF), and 1D‐Ripple Filter (1D‐RiFi) were created and exported as CAD mesh format files (.stl). An open‐source Python‐based script was used to convert them into voxels by endowing X, Y, and Z (following the Cartesian coordinates system) of solid materials in the three‐dimensional (3D) grid. A FLUKA (4‐2.2, CERN) predefined routine was used to establish the voxelized geometry model (VGM), while Flair (3.2‐1, CERN) was used to build the direct geometry model (DGM) in FLUKA for comparison purposes. Uniform carbon ion radiation fields 8×8 cm3 and 4×4 cm3 were generated to transport through the five pairs of models, 2D and 3D dose distributions were compared. The integral depth dose (IDD) in water of three different energy levels of carbon ion beams transported through 1D‐RiFis were also simulated and compared. Moreover, the volume between CAD mesh and VGMs, as well as the computing speed between FLUKA DGMs and VGMs were simultaneously recorded.ResultsThe volume differences between VGMs and CAD mesh models were not more than 0.6%. The maximum mean point‐to‐point deviation of IDD distribution was 0.7% ± 0.51% (mean ± standard deviation). The 3D dose Gamma‐index passing rates were never lower than 97% with criteria of 1%–1 mm. The difference in computing CPU time was 2.89% ± 0.22 on average.ConclusionsThe present study proposed and verified a Python‐based method for converting CAD mesh format files into VGMs and establishing them in FLUKA simply as well as accurately.