title: Benefits of online in vivo dosimetry for single-fraction total body irradiation.
abstract: Use of a patient test dose before single-fraction total body irradiation (TBI) allows review of in vivo dosimetry and modification of the main treatment setup. However, use of computed tomography (CT) planning and online in vivo dosimetry may reduce the need for this additional step. Patients were treated using a supine CT-planned extended source-to-surface distance (SSD) technique with lead compensators and bolus. In vivo dosimetry was performed using thermoluminescent dosimeters (TLDs) and diodes at 10 representative anatomical locations, for both a 0.1-Gy test dose and the treatment dose. In total, 28 patients were treated between April 2007 and July 2013, with changes made in 10 cases (36%) following test dose results. Overall, 98.1% of measured in vivo treatment doses were within 10% of the prescribed dose, compared with 97.0% of test dose readings. Changes made following the test dose could have been applied during the single-fraction treatment itself, assuming that the dose was delivered in subportions and online in vivo dosimetry was available for all clinically important anatomical sites. This alleviates the need for a test dose, saving considerable time and resources.
authors.affiliation: Department of Radiotherapy, Royal Free Hospital, London, UK. Electronic address: davideaton@nhs.net.
authors.forename: David J
authors.initials: DJ
authors.lastname: Eaton
authors.affiliation: Department of Radiotherapy Physics, University College London Hospital, London, UK.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Warry
authors.affiliation: Department of Radiotherapy, Royal Free Hospital, London, UK.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Trimble
authors.affiliation: Department of Radiotherapy, Royal Free Hospital, London, UK.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Vilarino-Varela
authors.affiliation: Department of Radiotherapy, Royal Free Hospital, London, UK.
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Collis
mesh_terms: D019583:Dose Fractionation, Radiation; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy*; D009862:Online Systems; D056888:Patient Positioning / Q000379:methods*; D011835:Radiation Protection / Q000379:methods*; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014916:Whole-Body Irradiation / Q000379:methods*
keywords: CT planning; Extended SSD; In vivo dosimetry; Total body irradiation