title: Comparison of composite prostate radiotherapy plan doses with dependent and independent boost phases.
abstract: Prostate cases commonly consist of dual phase planning with a primary plan followed by a boost. Traditionally, the boost phase is planned independently from the primary plan with the risk of generating hot or cold spots in the composite plan. Alternatively, boost phase can be planned taking into account the primary dose. The aim of this study was to compare the composite plans from independently and dependently planned boosts using dosimetric and radiobiological metrics. Ten consecutive prostate patients previously treated at our institution were used to conduct this study on the Raystation™ 4.0 treatment planning system. For each patient, two composite plans were developed: a primary plan with an independently planned boost and a primary plan with a dependently planned boost phase. The primary plan was prescribed to 54 Gy in 30 fractions to the primary planning target volume (PTV1) which includes prostate and seminal vesicles, while the boost phases were prescribed to 24 Gy in 12 fractions to the boost planning target volume (PTV2) that targets only the prostate. PTV coverage, max dose, median dose, target conformity, dose homogeneity, dose to OARs, and probabilities of benefit, injury, and complication-free tumor control (P+) were compared. Statistical significance was tested using either a 2-tailed Student's t-test or Wilcoxon signed-rank test. Dosimetrically, the composite plan with dependent boost phase exhibited smaller hotspots, lower maximum dose to the target without any significant change to normal tissue dose. Radiobiologically, for all but one patient, the percent difference in the P+ values between the two methods was not significant. A large percent difference in P+ value could be attributed to an inferior primary plan. The benefits of considering the dose in primary plan while planning the boost is not significant unless a poor primary plan was achieved.
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.|Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Narayanasamy
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Avila
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.|Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Panayiotis
authors.initials: P
authors.lastname: Mavroidis
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Niko
authors.initials: N
authors.lastname: Papanikolaou
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Alonso
authors.initials: A
authors.lastname: Gutierrez
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Diana
authors.initials: D
authors.lastname: Baacke
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA. stathakis@uthscsa.edu.|Department of Radiology, University of Texas Health Science Center at San Antonio, 7979 Wurzbach Rd, MC 7889, San Antonio, TX, 78229-4427, USA. stathakis@uthscsa.edu.
authors.forename: Sotirios
authors.identifier: http://orcid.org/0000-0002-7608-0612
authors.initials: S
authors.lastname: Stathakis
mesh_terms: D006801:Humans; D008297:Male; D008962:Models, Theoretical; D011336:Probability; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
keywords: Boost planning; Composite plan; Prostate radiation boost; Prostate radiobiology; Prostate radiotherapy