Shutter timer error for Co-60 arises due to finite travel time of the source to reach the treatment position.
It can be either positive or negative.
The length of a shutter timer error of a Co-60 unti is approximately 0.1 to 0.2 min.
It can be determined using an ionization chamber.
If the shutter timer error is positive to set the treatment time on the unit, it must be added to the computed "beam on " time. If negative obviously subtract it from the beam on time.
David, your blog topics are very useful to the medical physics students.
ReplyDeletecan you suggest some documents to find the shutter timer error?
Hi just noticed your comment today, I've not been real good about monitoring comments or even adding my own comments to these links.
ReplyDeleteHere is one paper i found on the topic, but will take a look for more.
http://ifm.org.my/sites/default/files/public%3A//publications/%5B015-019%5D-samat.pdf