PubMed · 5430832
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Y Umegaki. 1970-03-25. [Radiotherapy].. https://pubmed.ncbi.nlm.nih.gov/5430832/
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Stereotactic radiosurgery with a linear accelerator requires the accurate determination of a target volume and an accurate match of the therapeutic radiation dose distribution to the target volume. X ray and CT localizers have been described that are used to define the target volume or target point from angiographic or CT data. To verify the accuracy of these localizers, measurements were made with a target point simulator and an anthropomorphic head phantom. The accuracy of determining a known, high contrast, target point with these localizers was found to be a maximum of +/- 0.5 mm and +/- 1.0 mm for the X ray and CT localizer, respectively. A technique using portal X rays taken with a linear accelerator to verify the target point is also described.
A non-invasive head fixation system is described which is accurately relocatable and enables the transfer of stereotactic positions between a variety of radiodiagnostic images and therapeutic procedures. The system can be simply and repeatedly applied for planning stereotactic radiation therapy from one or more diagnostic images and for repeated treatment with a conventional linear accelerator. In addition, the long-term effects of therapy can be objectively monitored by relocating the frame and repeating images in an identical way, months or years later.
An adjustable portal film cassette holder has been designed and constructed. The holder provides for: holding portal film perpendicular to and centered with the central axis of the beam film-to-patient distance to minimize magnification; angling (swivel) film to match collimator angle; and ease of correct repositioning of arrangement when frequent filming is required. This device has now been in use for several months with good results.