title: Technical Note: Fabricating Cerrobend grids with 3D printing for spatially modulated radiation therapy: A feasibility study.
abstract: OBJECTIVE
  Grid therapy has promising applications in the radiation treatment of large tumors. However, research and applications of grid therapy are limited by the accessibility of the specialized blocks that produce the grid of pencil-like radiation beams. In this study, a Cerrobend grid block was fabricated using the 3D printing technique.
  
  
  METHODS
  A grid block mold was designed with flared tubes which follow the divergence of the beam. The mold was 3D printed using a resin with the working temperature below 230 °C. The melted Cerrobend liquid at 120 °C was cast into the resin mold to yield a block with a thickness of 7.4 cm. At the isocenter plane, the grid had a hexagonal pattern, with each pencil beam diameter of 1.4 cm; the distance between the beam centers was 2.1 cm.
  
  
  RESULTS
  The dosimetric properties of the grid block were studied using small field dosimeters: a pinpoint ionization chamber and a stereotactic diode. For a 6 MV photon beam, its valley-to-peak ratio was 20% at dmax and 30% at 10 cm depth; the output factor was 84.9% at dmax and 65.1% at 10 cm depth.
  
  
  CONCLUSIONS
  This study demonstrates that it is feasible to implement 3D printing technique in applying grid therapy in clinic.
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Joseph
authors.initials: J
authors.lastname: Driewer
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Sicong
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Vivek
authors.initials: V
authors.lastname: Verma
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Yu
authors.initials: Y
authors.lastname: Lei
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Mutian
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zheng
authors.affiliation: Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514.
authors.forename: Timothy
authors.initials: T
authors.lastname: Cullip
authors.affiliation: Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514.
authors.forename: Sha X
authors.initials: SX
authors.lastname: Chang
authors.affiliation: Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514.
authors.forename: Andrew Z
authors.initials: AZ
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Sumin
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Enke
mesh_terms: D000497:Alloys / Q000737:chemistry*; D017076:Computer-Aided Design; D019583:Dose Fractionation, Radiation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D010315:Particle Accelerators / Q000295:instrumentation*; D066330:Printing, Three-Dimensional; D020266:Radiotherapy, Conformal / Q000295:instrumentation*; D012542:Scattering, Radiation
chemical_list: D000497:Alloys