title: Linear energy transfer painting with proton therapy: a means of reducing radiation doses with equivalent clinical effectiveness.
abstract: OBJECTIVE
  The purpose of this study was to propose a proton treatment planning method that trades physical dose (D) for dose-averaged linear energy transfer (LETd) while keeping the radiobiologically weighted dose (DRBE) to the target the same.
  
  
  METHODS
  The target is painted with LETd by using 2, 4, and 7 fields aimed at the proximal segment of the target (split target planning [STP]). As the LETd within the target increases with increasing number of fields, D decreases to maintain the DRBE the same as the conventional treatment planning method by using beams treating the full target (full target planning [FTP]).
  
  
  RESULTS
  The LETd increased 61% for 2-field STP (2STP) compared to FTP, 72% for 4STP, and 82% for 7STP inside the target. This increase in LETd led to a decrease of D with 5.3 ± 0.6 Gy for 2STP, 4.4 ± 0.7 Gy for 4STP, and 5.3 ± 1.1 Gy for 7STP, keeping the Drbe at 90% of the volume (Drbe, 90) constant to FTP.
  
  
  CONCLUSIONS
  LETd painting offers a method to reduce prescribed dose at no cost to the biological effectiveness of the treatment.
authors.affiliation: Department of Radiation Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Medical Radiation Physics, Stockholm University, Stockholm, Sweden. Electronic address: Marcus.Fager@UPHS.UPenn.edu.
authors.forename: Marcus
authors.initials: M
authors.lastname: Fager
authors.affiliation: Medical Radiation Physics, Stockholm University and Karolinska Institutet, Stockholm, Sweden.
authors.forename: Iuliana
authors.initials: I
authors.lastname: Toma-Dasu
authors.affiliation: Department of Radiation Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Maura
authors.initials: M
authors.lastname: Kirk
authors.affiliation: Department of Radiation Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Derek
authors.initials: D
authors.lastname: Dolney
authors.affiliation: Department of Radiation Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Diffenderfer
authors.affiliation: Department of Radiation Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Neha
authors.initials: N
authors.lastname: Vapiwala
authors.affiliation: Department of Radiation Oncology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: Alejandro.Carabe-Fernandez@UPHS.UPenn.edu.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Carabe
mesh_terms: D006801:Humans; D018499:Linear Energy Transfer; D008297:Male; D058958:Organs at Risk; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D061766:Proton Therapy / Q000379:methods*; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D012007:Rectum; D012062:Relative Biological Effectiveness; D012189:Retrospective Studies; D001743:Urinary Bladder; D011522:Protons
chemical_list: D011522:Protons