Hello Qinqin,
notice that in ICRU145 the brain composition is given by mass percentage, while in your card you are giving the atomic fraction. Trying with your case, using the mass fraction, I obtained:
Average excitation energy : 7.3778E+01 eV, weighted Z/A : 5.5239E-01
Also, since you are using materials from databases, I suggest you to read slides 9 and 10 from the course lecture, they can be useful: https://indico.cern.ch/event/1123370/contributions/4715951/attachments/2445260/4189933/06_Materials_2022_ULB.pdf
Cheers,
Daniele