A previous audit of image quality in myocardial perfusion studies had suggested a variable dose schedule (VDS) based on patient weight would give more consistent results. We developed a simple quantitative measure, based on count density, which correlated with subjective image quality. Subjective image quality was scored using a scale from 1 to 4, where 4 was the highest quality. A score of 3 or above was defined as an image of acceptable diagnostic quality. From these results, a count density of 80 counts per pixel was chosen as the minimum target level to obtain quality images. This information was used to produce a VDS which varied from 200 MBq for patients weighing 60 kg, to 400 MBq for patients of 100 kg. These methods were then applied to 60 consecutive scans from 36 patients using the VDS. With the VDS, all scans were reported as being of acceptable image quality. Mean image score increased from 3.18 for the fixed dose schedule to 3.55 for the VDS. Forty-eight (80%) of the scans met the target count density. Mean count density increased from 84.8±21.1 (mean ±SD) to 92.7±15.4 (t test, P<0.05). The range of count densities decreased from 35-134 to 62-128, demonstrating a smaller variation using the VDS. Overall, the mean patient activity administered was increased by 22%. Eight patients (22%) received lower doses than they would have using the fixed dose regime. These results suggest that a VDS based on patient weight can result in more consistent image quality of myocardial perfusion studies with only a moderate overall increase in administered activity.
Chandler ST. Improved myocardial perfusion image quality with a variable dose schedule. Nuclear Medicine Communications: Volume 24(3) March 2003 p 339.
Mr. Steve Chandler, Darlington Unit, Darlington. Tel: +44 (0)1325-743-347.
Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne, NE4 6BE, UK.
Tel: +44 (0)191-233-6161 Fax: +44 (0)191-226-0970 E-mail: webmaster@rmpd.org.uk Web: http://www.rmpd.org.uk
By using this site you agree to our Terms and Conditions of Use. Please read our legal page.
Regional Medical Physics Department, a Clinical Directorate of the Newcastle upon Tyne Hospitals NHS Foundation Trust.
Copyright ©1999-2008 All Rights Reserved. Revised 28 April, 2008.
