177 / 1544
Ø
Wall mounted lasers / cross-hair
Ø
Visually aligning
Ø
Alignment accuracy
§
0.5-1.5 mm
Maciunas 2004
Lamba 2009
Invasive frame-based: targeting
7
g
Couch mounted positioning rely on:
Figure 1: The invasive head frame fixation (frame-based) (left) and the mask
immobilization (frameless approach) (right)
Finally, even with the technological advancements that enable a good dosimetrical
plan with sub-millimetric positioning of the target and immobilization of the patient,
some uncertainties in target localization and positioning are still present and must be
taken into account during a SRS treatment (9).
Evaluation of a stereotactic radiosurgery planning
1.2.1.
The large number of parameters involved in radiosurgery means that there are many
degrees of freedom so that many possibilities can be explored to achieve a desired
objective, but this also makes the task of finding the optimum choice very difficult.
The planner is faced with the often conflicting aims of making the radiation dose
conform as closely as possible with the treated volume, hereby minimizing the dose to
critical structures and brain (steep dose gradient), and maintaining dose uniformity in
the target (10). Therefore, treatment quality indices were made to analyze whether or
Invasive fixation
CT localization Isocenter localization
Positioning overlays