Читать книгу Leksell Radiosurgery - Группа авторов - Страница 55

When using stereotactic CT imaging instead of (or in addition to) MRI for frame-based SRS, it is advisable to use short posterior posts to avoid artifacts from the posts and pins. Care should also be taken in deciding the optimal place for the pins since they cause metallic artifacts on CT. An effort should be made to keep the lesion away from the pin artifacts. With modern CT scanners, 1.25- or 2.5-mm-thick slices (depending upon the size of the lesion) without any gap can be obtained in 1–2 min. CT scans can be especially useful in certain situations such as visualization of the cochlea in dose planning for vestibular schwannoma (Fig. 1). Before removing the patient from the CT table, accuracy checks are performed to make sure that images would be accepted by GammaPlan^® software.

Fig. 1. GammaPlan poster of a patient with vestibular schwannoma. Axial contrast-enhanced SPGR MRI, T2 volume MRI and CT images showing the position of the cochlea in relation to an enhancing tumor seen on SPGR images.