title: Geometric changes of parotid glands caused by hydration during chemoradiotherapy.
abstract: BACKGROUND
  Plan adaptation during the course of (chemo)radiotherapy of H&N cancer requires repeat CT scanning to capture anatomy changes such as parotid gland shrinkage. Hydration, applied to prevent nephrotoxicity from cisplatin, could temporarily alter the hydrogen balance and hence the captured anatomy. The aim of this study was to determine geometric changes of parotid glands as function of hydration during chemoradiotherapy compared to a control group treated with radiotherapy only.
  
  
  METHODS
  This study included an experimental group (n = 19) receiving chemoradiotherapy, and a control group (n = 19) receiving radiotherapy only. Chemoradiotherapy patients received cisplatin with 9 l of saline solution during hydration in the first, fourth and seventh week. The delineations of the parotid glands on the planning CT scan were automatically propagated to Cone Beam CT scans using deformable image registration. Relative volume and position of the parotid glands were determined at the second chemotherapy cycle (week four) and at fraction 35.
  
  
  RESULTS
  When saline solution was administrated, the volume temporarily increased on the first day (7.2 %, p < 0.001), second day (10.8 %, p < 0.001) and third day (7.0 %, p = 0.016). The gland positions shifted lateral, the distance between glands increased on the first day with 1.5 mm (p < 0.001), on the second day 2.2 mm (p < 0.001). At fraction 35, with both groups the mean shrinkage was 24 % ± 11 % (1SD) and the mean medial distance between the parotid glands decreased by 0.47 cm ± 0.27 cm.
  
  
  CONCLUSIONS
  Hydration significantly modulates parotid gland geometry. Unless, in the context of adaptive RT, a repeat CT scan is timed during a chemotherapy cycle, these effects are of minor clinical relevance.
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. n.kager@nki.nl.
authors.forename: Petronella M
authors.initials: PM
authors.lastname: Kager
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. s.v.weerdenburg@nki.nl.
authors.forename: Sanne C C
authors.initials: SC
authors.lastname: van Weerdenburg
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. s.v.kranen@nki.nl.
authors.forename: Simon R
authors.initials: SR
authors.lastname: van Kranen
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. s.v.beek@nki.nl.
authors.forename: Suzanne
authors.initials: S
authors.lastname: van Beek
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. e.lamers@nki.nl.|Division of Medical Technology, Inholland University of Applied Sciences, Bijdorplaan 15, 2015 CE, Haarlem, The Netherlands. e.lamers@nki.nl.
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Lamers-Kuijper
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. w.heemsbergen@nki.nl.
authors.forename: Wilma D
authors.initials: WD
authors.lastname: Heemsbergen
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. o.vrieze@nki.nl.
authors.forename: Olga
authors.initials: O
authors.lastname: Hamming-Vrieze
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. p.remeijer@nki.nl.
authors.forename: Peter
authors.initials: P
authors.lastname: Remeijer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059248:Chemoradiotherapy / Q000379:methods*; D002945:Cisplatin / Q000008:administration & dosage / Q000009:adverse effects; D054893:Cone-Beam Computed Tomography; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D006258:Head and Neck Neoplasms / Q000628:therapy*; D006801:Humans; D007674:Kidney Diseases / Q000139:chemically induced / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D010306:Parotid Gland / Q000000981:diagnostic imaging*; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000009:adverse effects; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012189:Retrospective Studies
chemical_list: D011838:Radiation-Sensitizing Agents; D002945:Cisplatin