Thephotoacoustictomographybyusingthehandheldprobehasagreatpotentialinclinicalbreastimaging.However,theshapeoftheprobelimitsthechoiceoflightdeliveryinthissetup.Inthisletter,westudytwocommonlyusedilluminationtypesforhandheldprobe:bright-fieldilluminationanddark-fieldillumination.Ourresultsdemonstrateseveralparametershaveimportantimpactonthephotonfluenceindeepbreasttissue.Theresultswillhelptooptimizethedesignofthephotoacousticbreastimagingsystemwithahandheldprobe.
