Jc. Flickinger et al., POTENTIAL HUMAN ERROR IN SETTING STEREOTAXIC COORDINATES FOR RADIOSURGERY - IMPLICATIONS FOR QUALITY ASSURANCE, International journal of radiation oncology, biology, physics, 27(2), 1993, pp. 397-401
Citations number
6
Categorie Soggetti
Oncology,"Radiology,Nuclear Medicine & Medical Imaging
Purpose: The error frequency in setting stereotactic coordinates for g
amma knife radiosurgery was investigated to determine what quality ass
urance safeguards are necessary. Methods and Materials: A prospective
study of 200 consecutive isocenter settings for gamma knife radiosurge
ry was analyzed to identify the frequency of spontaneous errors in set
ting and checking stereotactic coordinates (corrected prior to treatme
nt). An additional 25 coordinate errors were introduced at random amon
g the next 200 consecutive isocenter settings to provide additional da
ta on identification of errors. Results: Stereotactic coordinates requ
ired resetting in 12% (24/200) of the isocenters treated due to errors
of 0.25-0.50 mm (8%) and 1-20 mm (4%). This comprised 2.2% (26/1200)
of the individual coordinate settings. The frequency of these errors w
as significantly related to the specific directional coordinate set (p
= 0.0004) and experience (p = 0.016). Errors were identified by 83.5%
(91/109) of the observers checking the settings (60.0% of 0.25 mm err
ors, 94.6% of errors greater-than-or-equal-to 0.5 mm, p = 0.0000). Ver
ification of stereotactic coordinates by two observers reduces the pro
bability of an undetected error greater-than-or-equal-to 0.25 mm to 1/
1,392 and to 1/154,712 for errors greater-than-or-equal-to 1 mm. Concl
usion: Errors in setting stereotactic coordinates are common (12% prio
r to checking) but are corrected with a high degree of confidence by a
quality assurance policy requiring coordinate verification by a minim
um of two observers.