title: A customized bolus produced using a 3-dimensional printer for radiotherapy.
abstract: OBJECTIVE
  Boluses are used in high-energy radiotherapy in order to overcome the skin sparing effect. In practice though, commonly used flat boluses fail to make a perfect contact with the irregular surface of the patient's skin, resulting in air gaps. Hence, we fabricated a customized bolus using a 3-dimensional (3D) printer and evaluated its feasibility for radiotherapy.
  
  
  METHODS
  We designed two kinds of bolus for production on a 3D printer, one of which was the 3D printed flat bolus for the Blue water phantom and the other was a 3D printed customized bolus for the RANDO phantom. The 3D printed flat bolus was fabricated to verify its physical quality. The resulting 3D printed flat bolus was evaluated by assessing dosimetric parameters such as D1.5 cm, D5 cm, and D10 cm. The 3D printed customized bolus was then fabricated, and its quality and clinical feasibility were evaluated by visual inspection and by assessing dosimetric parameters such as Dmax, Dmin, Dmean, D90%, and V90%.
  
  
  RESULTS
  The dosimetric parameters of the resulting 3D printed flat bolus showed that it was a useful dose escalating material, equivalent to a commercially available flat bolus. Analysis of the dosimetric parameters of the 3D printed customized bolus demonstrated that it is provided good dose escalation and good contact with the irregular surface of the RANDO phantom.
  
  
  CONCLUSIONS
  A customized bolus produced using a 3D printer could potentially replace commercially available flat boluses.
authors.affiliation: Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Shin-Wook
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Hun-Joo
authors.initials: HJ
authors.lastname: Shin
authors.affiliation: Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Chul Seung
authors.initials: CS
authors.lastname: Kay
authors.affiliation: Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Son
mesh_terms: D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy*; D019047:Phantoms, Imaging; D066330:Printing, Three-Dimensional; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted