| Autor: |
Arnot, R. N., Willetts, R. J., Batten, J. R., Orr, J. S. |
| Zdroj: |
The British Journal of Radiology; January 1984, Vol. 57 Issue: 673 p47-55, 9p |
| Abstrakt: |
A method for computed tomography using equipment available on some radiotherapy simulators has been investigated. An offset narrow fan beam of X rays passes transversely through the object and is continuously detected by an image intensifier and TV camera system while the beam and detector complete a rotation about the object in 30 seconds. Several TV lines of the images obtained at equal angular increments are digitised and summed to produce transmission projections from which a transverse section is formed by filtered back-projection. The dynamic range required of the camera is reduced by modifying the beam with a shaped metal filter. Images are produced without logarithmic processing or X-ray output calibration. Digital control circuitry is used for digitisation and spatial filtering, and a high-speed arithmetic array processor and digital frame store are used for back projection and image storage (Cynosure Imaging Systems Ltd.). Phantom studies using an object on a turntable with a stationary X-ray tube and intensifier showed the system to be capable of good spatial resolution and reasonable density resolution. Acceptable images of humans have been produced with the equipment added to a Ximascan simulator (TEM Instruments Ltd.). Radiation dose to the irradiated section can be as little as 200 µGy (20 mrad). |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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