Περίληψη:
The prototype of a stereotactic collimator set developed in our
department is evaluated for clinical use. This set consists of three
cylindrical blocks mounted on a tray which slides in the wedge insert of
a Siemens Primus accelerator. Each block has a collimating hole along
its long axis to produce radiation fields of circular cross-section at
the isocentre plane with diameters of 15 mm, 20 mm and 25 mm. Different
geometric and dosimetric quality assurance tests were performed and
results are found within the limits set for stereotactic radiotherapy.
Dosimetry results measured using Kodak EDR-2 radiographic film and a
pinpoint ion chamber also show good agreement with corresponding results
calculated by Monte Carlo simulation of the linear accelerator head and
the collimators. Measured dosimetry data were used to adapt a
conventional PLATO treatment planning system for stereotactic
radiotherapy using the prototype collimator set. Treatment planning
system calculations and film measurements for treatment of an
intracranial lesion in an anthropomorphic head phantom using coplanar
180 degrees arcs are compared and found to agree within 2 mm. This
supports the accuracy of dose delivery using the prototype stereotactic
collimators. Despite their increased penumbra (2.5-3.5 mm relative to
2-2.5 mm for commercially available collimators) the ease of
construction makes the proposed stereotactic collimators an interesting
alternative for accomplishing cost effective stereotactic treatments.
Συγγραφείς:
Paschalis, T.
Sandilos, P.
Tatsis, E.
Karaiskos, P. and
Antypas, C.
Chatzigiannis, C.
Dardoufas, K.
Georgiou, E. and
Vlachos, L.
