title: Feasibility of using two-dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry.
abstract: Two-dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from -0.2% ~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry.
authors.affiliation: Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL, USA. hchung1@mdanderson.org
authors.forename: Heeteak
authors.initials: H
authors.lastname: Chung
authors.forename: Jonathan
authors.initials: J
authors.lastname: Li
authors.forename: Sanjiv
authors.initials: S
authors.lastname: Samant
mesh_terms: D000465:Algorithms; D002138:Calibration; D005240:Feasibility Studies; D005373:Film Dosimetry / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D006801:Humans; D009369:Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D010315:Particle Accelerators; D019047:Phantoms, Imaging; D011786:Quality Control; D011836:Radiation Tolerance; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D015203:Reproducibility of Results; D012542:Scattering, Radiation