The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  X  1  2  1  1  X  2  X
 0 2X+2  0  2  0 2X 2X+2 2X+2  0 2X  2 2X+2  0  2  0 2X+2  2 2X+2 2X+2  2 2X
 0  0 2X+2  2  0  2  2 2X  0  2  2  0 2X 2X+2  2 2X  0 2X+2  0 2X+2 2X
 0  0  0 2X  0  0 2X  0 2X 2X  0 2X 2X  0 2X 2X 2X  0  0  0 2X
 0  0  0  0 2X 2X 2X 2X 2X 2X  0 2X  0 2X 2X 2X 2X 2X 2X 2X 2X

generates a code of length 21 over Z4[X]/(X^2+2) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+81x^18+96x^19+192x^20+320x^21+179x^22+96x^23+26x^24+23x^26+4x^28+5x^30+1x^32

The gray image is a code over GF(2) with n=168, k=10 and d=72.
This code was found by Heurico 1.16 in 56.7 seconds.