A radiation detector head assembly is provided that includes a detector housing and a detector unit. The detector housing defines a cavity therein. The detector housing includes a shell and a shielding body. The shell defines at least a portion of a perimeter surrounding the shielding body, and includes an extrusion defining the at least a portion of a perimeter. The extrusion is formed from a first material that is configured for rigidity. The shielding body includes a second material configured to shield radiation. The detector unit is disposed within the cavity, and includes an absorption member and associated processing circuitry.