The MIRD and the RADAR Systems

 

The MIRD System

The equation for absorbed dose in the MIRD system (Loevinger et al. 1988) is deceptively simple:


(12)


No one is fooled by now, of course. The cumulated activity is there; all other terms must be lumped in the factor S, and so they are:

(13)



In the MIRD equation, the factor k is 2.13, which gives doses in rad, from activity in microcuries, mass in grams, and energy in MeV. The MIRD system was developed primarily for use in estimating radiation doses received by patients from administered radiopharmaceuticals; it is not intended to be applied to a system of dose limitation for workers.

The RADAR System

A new on-line information system has been developed, named the RAdiation Dose
Assessment Resource, or RADAR. The idea of this system is to incorporate the useful information in all of the above systems, but using a single equation (as we have learned that one equation is all we need). This single equation is:

(14)


Nothing new here, as with any system ­ we only hope that the names of the terms make more sense. NS is the number of disintegrations that occurred in a source region, and DF(TS) is the dose conversion factor for region T irradiating region S (Gy per disintegration). The DF contains the expected quantities:

(15)

This looks most like the MIRD system, and functions in the same way. The power of the RADAR system is that all of the important data from existing MIRD and ICRP models and documents have been incorporated into this system and are accessible to a large extent on line. Users can download DCFs and values of NS, as well as information on the bases of the models, assumptions, etc. Learning just the one equation above, the user can access all of the useful information in both systems. In addition, the RADAR web site has many useful documents that give guidance on how to collect the appropriate data for practical application of either system, how to best apply models, interpret biological effects, etc.



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