Position displacement effect on the doses in the peripheral head regions

Mika Kortesniemi, Tom Seren, Tiina Seppälä, Ritva Parkkinen, Hanna Bjugg, Petri Kotiluoto, Iiro Auterinen, Sauli Savolainen

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review


    Patient positioning is a challenging task in BNCT-treatments due to the use of multiple fields and a static horizontal beam construction. Positioning accuracy of 5 mm is required for acceptable dose delivery within appropriate limits of dose uncertainty (up to 10% of point dose in target volume). The aim of this study was to determine if a patient head position creating a clear gap between the beam port and the head would have a significant effect on the doses to the peripheral regions of the head, e.g. to the eyes. The gamma dose rates were measured in a water filled ellipsoidal phantom with an ionisation chamber (IC). Mn activation wires were used to determine the Mn-55(n, γ) reaction rates. Twelve measurement points were chosen in the phantom and two phantom positions were applied. According to this study the 35 mm position change and the resulting gap has an obvious effect on the peripheral doses in BNCT. The Mn activation reaction rates were on the average 80% higher in the deviation position than in the reference position. Increasing depth from the surface inside the phantom diminished the gamma dose difference between the two positions. Scattering environment changes with position displacement and resulting gap causes differences in neutron fluences and gamma doses.

    Original languageEnglish
    Title of host publicationProceedings of the ninth international symposium on neutron capture therapy for cancer
    Place of PublicationOsaka
    Pages283 - 284
    Publication statusPublished - 2000
    MoE publication typeA4 Article in a conference publication
    Event9th International Symposium on Neutron Capture Therapy for Cancer: NCT Osaka 2000 - Osaka, Japan
    Duration: 2 Oct 20006 Oct 2000


    Conference9th International Symposium on Neutron Capture Therapy for Cancer


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