Dicom integration

I integrate dicom in my rails application that purpose i install RMagick
gem then the following errors are came.
C:\Ruby187\bin>gem install RMagick
Temporarily enhancing PATH to include DevKit...
Building native extensions. This could take a while...
ERROR: Error installing RMagick:
        ERROR: Failed to build gem native extension.
        C:/Ruby187/bin/ruby.exe extconf.rb
checking for Ruby version >= 1.8.5... yes
Invalid drive specification.
Unable to get ImageMagick version
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.
Provided configuration options:

Gem files will remain installed in
3.1 for inspection.
Results logged to
can any one please suggest me a proper solution.
Thank you.