For those needing portability, Rad Pro for Desktop works with Windows 8.1/10 tablets. Will not work with Surface tablets running Windows RT.
Select Calculation     
Enter Known Dose-Rate   At Known Distance (Enter) Initial Data      mR/hr Feet
  mR Enter Dose Limit     Feet Enter Distance Hours Calculated Stay Time   Select Dose-Rate Units   Select Stay Time Units Select Dose Limit Units   Select Distance Units   ALARA Calculations (Time, Distance and Shielding)     

Classic time, distance and shielding ALARA calculations.  The known dose-rate may be from in field measurements or if the isotope and activity of the source are known, the Rad Pro Calculator gamma calculator may be used to calculate it.  If the working distance and exposure limit are known, the stay time until the limit is reached may be calculated.  If the time to complete the job and the exposure limit are known, the working distance may be calculated.  If the working distance and the time to do the job are known, the exposure received may be calculated.  In all cases, shielding may be added to increase the stay time or decrease the working distance.