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A conformity index is a measure of how well the volume of a radiosurgical dose distribution conforms to the size and shape of a target volume. Because the success of radiosurgery is related to the extremely conformal irradiation of the target, an accurate method for describing this parameter is important. Existing conformity ratios and indices used in(More)
A dose gradient index (GI) is proposed that can be used to compare treatment plans of equal conformity. The steep dose gradient outside the radiosurgical target is one of the factors that makes radiosurgery possible. It therefore makes sense to measure this variable and to use it to compare rival plans, explore optimal prescription isodoses, or compare(More)
Chemotherapy has made substantial progress in the therapy of systemic cancer, but the pharmacological efficacy is insufficient in the treatment of brain metastases. Fractionated whole brain radiotherapy (WBRT) has been a standard treatment of brain metastases, but provides limited local tumor control and often unsatisfactory clinical results. Stereotactic(More)
OBJECTIVE The objective of this study is to introduce a new radiosurgical device, the Leksell Gamma Knife Perfexion (Elekta Instruments AB, Stockholm, Sweden). Design and performance characteristics are compared with previous models of the gamma knife in a clinical setting. METHODS Performance-related features in the design of the new radiosurgical system(More)
The aim of this study was to investigate the effect of gamma knife surgery on the local control of cerebral metastases from melanoma and to assess survival. In 29 patients, 105 of 178 cerebral metastases were treated with gamma knife surgery. Only five patients had metastases confined to the brain. Of the 96 metastases with magnetic resonance imaging(More)
The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the international formalism published by(More)
BACKGROUND AND PURPOSE Radiotherapy is used to reverse or prevent local tumour growth but is also a carcinogen in its own right. A recent audit of post-radiotherapy second malignancies in this institution revealed a striking preponderance of tumours originating near the outside edge of the treatment field. Since this finding suggests the existence of a(More)
OBJECT This report has been prepared to ensure more uniform reporting of Gamma Knife radiosurgery treatment parameters by identifying areas of controversy, confusion, or imprecision in terminology and recommending standards. METHODS Several working group discussions supplemented by clarification via email allowed the elaboration of a series of provisional(More)
The struggle to achieve a high degree of conformity around targets of complex morphology has been one of the driving forces in the development of ever more sophisticated radiosurgical devices and intricate treatment delivery. Rarely are radiosurgical targets more complex in shape than those associated with arteriovenous malformations (AVMs). In this report(More)
Radiosurgery (RS) treatment times vary, even for the same prescription dose, due to variations in the collimator size, the number of iso-centres/beams/arcs used and the time gap between each of these exposures. The biologically effective dose (BED) concept, incorporating fast and slow components of repair, was used to show the likely influence of these(More)