title: Implementation of an intraoperative electron radiotherapy in vivo dosimetry program.
abstract: BACKGROUND
  Intraoperative electron radiotherapy (IOERT) is a highly selective radiotherapy technique which aims to treat restricted anatomic volumes during oncological surgery and is now the subject of intense re-evaluation. In vivo dosimetry has been recommended for IOERT and has been identified as a risk-reduction intervention in the context of an IOERT risk analysis. Despite reports of fruitful experiences, information about in vivo dosimetry in intraoperative radiotherapy is somewhat scarce. Therefore, the aim of this paper is to report our experience in developing a program of in vivo dosimetry for IOERT, from both multidisciplinary and practical approaches, in a consistent patient series. We also report several current weaknesses.
  
  
  METHODS
  Reinforced TN-502RDM-H mobile metal oxide semiconductor field effect transistors (MOSFETs) and Gafchromic MD-55-2 films were used as a redundant in vivo treatment verification system with an Elekta Precise fixed linear accelerator for calibrations and treatments. In vivo dosimetry was performed in 45 patients in cases involving primary tumors or relapses. The most frequent primary tumors were breast (37 %) and colorectal (29 %), and local recurrences among relapses was 83 %. We made 50 attempts to measure with MOSFETs and 48 attempts to measure with films in the treatment zones. The surgical team placed both detectors with supervision from the radiation oncologist and following their instructions.
  
  
  RESULTS
  The program was considered an overall success by the different professionals involved. The absorbed doses measured with MOSFETs and films were 93.8 ± 6.7 % and 97.9 ± 9.0 % (mean ± SD) respectively using a scale in which 90 % is the prescribed dose and 100 % is the maximum absorbed dose delivered by the beam. However, in 10 % of cases we experienced dosimetric problems due to detector misalignment, a situation which might be avoided with additional checks. The useful MOSFET lifetime length and the film sterilization procedure should also be controlled.
  
  
  CONCLUSIONS
  It is feasible to establish an in vivo dosimetry program for a wide set of locations treated with IOERT using a multidisciplinary approach according to the skills of the professionals present and the detectors used; oncological surgeons' commitment is key to success in this context. Films are more unstable and show higher uncertainty than MOSFETs but are cheaper and are useful and convenient if real-time treatment monitoring is not necessary.
authors.affiliation: Servicio de Radiofísica y Protección Radiológica, Consorcio Hospitalario Provincial de Castellón, Avda. Dr. Clará, nº 19, Castellón de la Plana, 12004, Castellón, Spain. lopez_juatar@gva.es.
authors.forename: Juan
authors.identifier: http://orcid.org/0000-0002-6997-1521
authors.initials: J
authors.lastname: López-Tarjuelo
authors.affiliation: Servicio de Oncología Radioterápica, Consorcio Hospitalario Provincial de Castellón, Castellón de la Plana, Spain.|Unitat predepartamental de Medicina, Facultat de Ciències de la Salut, Universitat Jaume I, Avda. Vicent Sos Baynat, s/n, Castellón de la Plana, 12071, Castellón, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Morillo-Macías
authors.affiliation: Servicio de Oncología Radioterápica, Consorcio Hospitalario Provincial de Castellón, Castellón de la Plana, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Bouché-Babiloni
authors.affiliation: Unidad de Cirugía Oncológica, Servicio de Cirugía, Consorcio Hospitalario Provincial de Castellón, Castellón de la Plana, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Boldó-Roda
authors.affiliation: Unidad de Cirugía Oncológica, Servicio de Cirugía, Consorcio Hospitalario Provincial de Castellón, Castellón de la Plana, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Lozoya-Albacar
authors.affiliation: Servicio de Oncología Radioterápica, Consorcio Hospitalario Provincial de Castellón, Castellón de la Plana, Spain.|Departamento de Medicina y Cirugía, Facultad de Ciencias de la Salud, Universidad Cardenal Herrera-CEU, C/ Grecia 31, Castellón de la Plana, 12006, Castellón, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Ferrer-Albiach
mesh_terms: D002138:Calibration; D004583:Electrons; D005373:Film Dosimetry / Q000191:economics / Q000379:methods; D006801:Humans; D007432:Intraoperative Period; D008670:Metals / Q000737:chemistry*; D009364:Neoplasm Recurrence, Local; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000628:therapy*; D010087:Oxides / Q000737:chemistry; D010315:Particle Accelerators; D011076:Polycarboxylate Cement / Q000737:chemistry; D011874:Radiometry / Q000379:methods*; D011878:Radiotherapy / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage; D012008:Recurrence; D015203:Reproducibility of Results; D012306:Risk; D040242:Risk Reduction Behavior; D012666:Semiconductors
chemical_list: D008670:Metals; D010087:Oxides; D011076:Polycarboxylate Cement; C005506:polycarbonate
keywords: In vivo dosimetry; Intraoperative radiotherapy; MOSFETs; Oncological surgery; Radiochromic films