- m_dAngularDetIncrement = 2 * m_detInc; // Angular Position 2x gamma angle
- m_dAngularDetLen = 2 * m_detLen + 2 * dDetectorArrayEndOffset;
+ // adjust for center-detector length
+ double dA1 = acos ((m_dScanDiameter / 2) / m_dCenterDetectorLength);
+ double dAngularScale = 2 * (HALFPI + dAngle - dA1) / m_detLen;
+
+ m_dAngularDetLen = dAngularScale * (m_detLen + dDetectorArrayEndOffset);
+ m_dAngularDetIncrement = dAngularScale * m_detInc;