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Physical characteristics of a low‐dose gas microstrip detector for orthopedic x‐ray imaging
Author(s) -
Després Philippe,
Beaudoin Gilles,
Gravel Pierre,
de Guise Jacques A.
Publication year - 2005
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1876592
Subject(s) - detector , x ray detector , orthopedic surgery , medical imaging , medical physics , nuclear medicine , physics , optics , medicine , materials science , radiology , surgery
A new scanning slit gas detector dedicated to orthopedic x‐ray imaging is presented and evaluated in terms of its fundamental imaging characteristics. The system is based on the micromesh gaseous structure detector and achieves primary signal amplification through electronic avalanche in the gas. This feature, together with high quantum detection efficiency and fan‐beam geometry, allows for imaging at low radiation levels. The system is composed of 1764 channels spanning a width of44.8 cmand is capable of imaging an entire patient at speeds of up to15 cm ∕ s . The resolution was found to be anisotropic and significantly affected by the beam quality in the horizontal direction, but otherwise sufficient for orthopedic studies. As a consequence of line‐by‐line acquisition, the images contain some ripple components due to mechanical vibrations combined with variations in the x‐ray tube output power. The reported detective quantum efficiency (DQE) values are relatively low (0.14 to 0.20 at0.5mm − 1) as a consequence of a suboptimal collimation geometry. The DQE values were found to be unaffected by the exposure down to7 μ Gy , suggesting that the system is quantum limited even for low radiation levels. A system composed of two orthogonal detectors is already in use and can produce dual‐view full body scans at low doses. This device could contribute to reduce the risk of radiation induced cancer in sensitive clientele undergoing intensive x‐ray procedures, like young scoliotic women.