Published in:
01-10-2014 | Original article
In vivo dosimetry in intraoperative electron radiotherapy
microMOSFETs, radiochromic films and a general-purpose linac
Published in: Strahlentherapie und Onkologie | Issue 11/2014
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Introduction
In vivo dosimetry is desirable for the verification, recording, and eventual correction of treatment in intraoperative electron radiotherapy (IOERT). Our aim is to share our experience of metal oxide semiconductor field–effect transistors (MOSFETs) and radiochromic films with patients undergoing IOERT using a general-purpose linac.
Materials and methods
We used MOSFETs inserted into sterile bronchus catheters and radiochromic films that were cut, digitized, and sterilized by means of gas plasma. In all, 59 measurements were taken from 27 patients involving 15 primary tumors (seven breast and eight non-breast tumors) and 12 relapses. Data were subjected to an outliers’ analysis and classified according to their compatibility with the relevant doses. Associations were sought regarding the type of detector, breast and non-breast irradiation, and the radiation oncologist’s assessment of the difficulty of detector placement. At the same time, 19 measurements were carried out at the tumor bed with both detectors.
Results
MOSFET measurements (\(\overline{D}\) = 93.5 %, sD = 6.5 %) were not significantly shifted from film measurements (\(\overline{D}\) = 96.0 %, sD = 5.5 %; p = 0.109), and no associations were found (p = 0.526, p = 0.295, and p = 0.501, respectively). As regards measurements performed at the tumor bed with both detectors, MOSFET measurements (\(\overline{D}\) = 95.0 %, sD = 5.4 % were not significantly shifted from film measurements (\(\overline{D}\) = 96.4 %, sD = 5.0 %; p = 0.363).
Conclusion
In vivo dosimetry can produce satisfactory results at every studied location with a general-purpose linac. Detector choice should depend on user factors, not on the detector performance itself. Surgical team collaboration is crucial to success.