Einfluss von Strahlendosis, Sichtfeld und beweglicher Lokalisatorplatte auf die Registriergenauigkeit stereotaktischer Rahmensysteme
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Philipps-Universität Marburg
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Abstract
Frame-based stereotaxy represents a cornerstone technique in the management of neu-rodegenerative disorders. The accurate implantation of electrodes into the brain requires a system that can meet the high standards for precision. This can be achieved through the use of stereotactic frames which enable the precise implantation of electrodes at the intended target site.
The individual steps of a stereotactic procedure include attaching the frame system, reg-istration of the stereotactic frame, trajectory planning and the subsequent surgical proce-dure. Influences on the registration of the frame systems, for example through parame-ters such as dose, size of field of view or frame-specific structures, in this case the mov-able localizer plate of a frame, have hardly been investigated so far. The aim of this study was therefore to investigate the influence of these factors on localization accuracy during registration of stereotactic frame systems.
As part of the studies, measurements were carried out to analyze the effect of radiation dose and field of view on the localization accuracy during stereotactic frame registration. For this purpose, two different frame systems were attached to an anthropomorphic phantom. These were the Zamorano-Duchovny frame (ZD, Co. Inomed) and the Vantage frame (LV, Co. Leksell). Both, the CT protocol (Head, Orbita, Sinus, Sinus 80%, Sinus 5 mA and Newborn protocol) and the field of view size (30, 35, 40, 45 and 50 cm, each in the Head and Newborn protocols), respectively, were varied. Subsequently, the localiza-tion and statistical evaluation of the localization accuracy were analyzed.
Another part of this work was to analyze the influence of the movable localizer plate of the ZD frame on registration accuracy. Therefore, a comparison was initially conducted between the four localizer plates. In Addition, a retrospective analysis was conducted on data from 83 electrode implantations to determine whether the movable plate exerted an influence on the target point coordinates of planned trajectories.
The evaluation of the influence of radiation dose showed that a reduction in applied dose by choosing different CT protocols did not result in a notable decline in localization accu-racy of both frame systems. On the contrary, a comparison of the results revealed that a higher registration accuracy could be determined for measurements using the protocol with the lowest applied radiation dose (Newborn protocol) compared to the other proto-cols.
Investigation of the field of view and its impact on localization accuracy revealed that the accuracy deteriorated with increasing edge length, irrespective of the CT protocols em-ployed. The determined differences were within the low three-digit micrometer range.
It was further demonstrated that the movable anterior plate of the ZD frame, compared to the other plates of the frame, was localized the poorest, with 87% of the outliers attribut-able to the rods of this plate. This had a significant impact on two out of three target point coordinates of the trajectories planned for surgeries on patients, resulting in an average distance of 0.24 mm between the target points when the plate was added (LARP) and removed (RPL), respectively.
In conclusion, the results demonstrated that low-dose protocols can be employed for the accurate localization of stereotactic frames without compromising the precision of frame registration. This is associated with a reduction in the applied radiation dose to less than 1% compared to the high-dose protocol, which means that potentially harmful radiation can be reduced and long-term consequences avoided. Moreover, the findings of this study indicated that augmented field of view was linked to diminished localization preci-sion. Nevertheless, given the minimal magnitude of these discrepancies, a comprehen-sive risk-benefit assessment is imperative prior to modifying the field of view. Finally, the results of this study showed that the anterior localizer plate of the ZD frame was localized to a significantly lesser degree than the other plates, thereby influencing the target point coordinates of planned trajectories. Therefore, a critical assessment should be made as to whether the frontal plate of the ZD frame should be included in the registration pro-cess.
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Created: 2025Issued: 2025-09-15Updated: 2025-09-15
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Medizin
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Philipps-Universität Marburg
Language
ger
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DoctoralThesis
Keywords
localizerstereotaxyframe systemradiation doseregistration accuracyfield of viewlocalizationregistrationlocalizer plate
DFG-subjects
StrahlendosisLokalisatorplatteRegistrierungLokalisationSichtfeldLokalisatorRahmensystemStereotaxieRegistriergenauigkeit
DDC-Numbers
610
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Kröncke, Noel Joshua: Einfluss von Strahlendosis, Sichtfeld und beweglicher Lokalisatorplatte auf die Registriergenauigkeit stereotaktischer Rahmensysteme. : Philipps-Universität Marburg 2025-09-15. DOI: https://doi.org/10.17192/z2025.0040.
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This item has been published with the following license: In Copyright