Out-of-field doses in children treated for large arteriovenous malformations using hypofractionated gamma knife radiosurgery and intensity-modulated radiation therapy

Research output: Contribution to journalArticle

Authors

  • Marijke De Saint-Hubert
  • Marija Majer
  • Hrvoje Hraak
  • Zdravko Heinrich
  • Zeljka Knezevic
  • Saveta Miljanic
  • Paulina PorwoB
  • Liliana Stolarczyk
  • Roger M Harrison

Institutes & Expert groups

  • RBI - Ruđer Bošković Institute
  • University Hospital Centre Zagreb
  • Radiology Therapeutic Centre Poland SP. Z O.O.
  • PAS - Institute of physics - Polish academy of sciences
  • Newcastle University - Institute of Health and Society

Documents & links

DOI

Abstract

The purpose of this study was to measure out-of-field organ doses in two anthropomorphic child phantoms for the treatment of large brain arteriovenous malformations (AVMs) using hypofractionated gamma knife (GK) radiosurgery and to compare these with an alternative treatment using intensity-modulated radiation therapy (IMRT). Target volume was identical in size and shape in all cases. Radiophotoluminescent (RPL), thermoluminescent (TL) and optically stimulated luminescent (OSL) dosimeters were used for out-of-field dosimetry during GK treatment and a good agreement within 1–2% between results was shown. In addition, the use of multiple dosimetry systems strengthens the reliability of the findings. The number of GK isocentres was confirmed to be important for the magnitude of out-of-field doses. Measured GK doses for the same distance from the target, when expressed per target dose and isocentre, were comparable in both phantoms. GK out-of-field doses averaged for both phantoms were evaluated to be 120 mGy/Gy for eyes then sharply reduced to 20 mGy/Gy for mandible and slowly reduced up to 0.8 mGy/Gy for testes. Taking into account the fractionation regimen used to treat AVM patients, the total treatment organ doses to the out-of-field organs were calculated and compared with IMRT. The eyes were better spared with GK whilst for more distant organs doses were up to a factor of 2.8 and 4 times larger for GK compared to IMRT in 5-year and 10-year old phantoms, respectively. Presented out-of-field dose values are specific for the investigated AVM case, phantoms and treatment plans used for GK and IMRT, but provide useful information about out-of-field dose levels and emphasise their importance.

Details

Original languageEnglish
Pages (from-to)1-11
JournalRadiation protection dosimetry
Volume181
Issue number2
DOIs
Publication statusPublished - 17 Jan 2018

Keywords

  • out-of-field dose, Radiotherapy, Radioprotection, gamma knife, IMRT

ID: 3777731