RE: Model estimate of dose

From: Johan.Rosenborg@astrazeneca.com Subject: RE: [NMusers] Model estimate of dose Date: Tue, December 7, 2004 9:39 am Dear Anthe, Sam and Nick, Thank you for your concern in this matter and your suggestion to moderate the measured dose via F (Sorry for my late feedback!). A further clarification to my question may be appropriate. A radiactive substance was administered via the lungs. Radiactivity was measured at 2-min intervals with a gamma camera on several occasions up to a few hours post-dose; the primary estimate of the amount deposited in the airways - the dose - was based on the first measurement. What I would like to do is to fit a model to the gamma camera measurements as a means to estimate the amount at time zero by back extrapolation, so to say. If the radioactive tracer is deposited in CMT=n, it should be possible to estimate the amount - the dose - at time zero as follows: A(n) = THETA(X)*EXP(ETA(Y)) x AMT (a unit dose is assigned to the deposition compartment in the data file, i.e. AMT=1 in the record where CMT=n, TIME=0 and EVID=4) Any suggestion on how to proceed with this idea? / Johan > Johan Rosenborg > AstraZeneca R&D Lund > Experimental Medicine, S-221 87 Lund, Sweden > Tel: +46 46 33 65 99 Fax: +46 46 33 71 91 > E-mail: johan.rosenborg@astrazeneca.com