The generator matrix

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

generates a code of length 24 over Z3[X]/(X^2) who´s minimum homogenous weight is 48.

Homogenous weight enumerator: w(x)=1x^0+72x^48+8x^54

The gray image is a linear code over GF(3) with n=72, k=4 and d=48.
As d=48 is an upper bound for linear (72,4,3)-codes, this code is optimal over Z3[X]/(X^2) for dimension 4.
This code was found by Heurico 1.16 in 0.00125 seconds.