The interaction cross sections (σ I 's) with 1 5 B, 9 C, 1 0 C, 1 5 C, 1 3 N, 1 3 O, 1 4 O and 1 5 O beams have been measured at energies of around 730A MeV. The effective root-mean-square (RMS) radii of the nucleon distribution of these nuclei have been deduced using a Glauber-model calculation. The global isotope and isospin dependences of the radii are shown in the p-shell region. The σ I 's are also compared with those obtained at intermediate energies in the region. Furthermore, we calculated the Coulomb-energy differences of the mirror pairs deduced from the RMS charge radii and compared them with those obtained from the mass for some mirror pairs. From the above systematics, an anomalous nuclear structure (a halo and/or a skin) is suggested for 1 4 B and 1 5 C, and the occurrence of an s-d inversion is emphasized for the 1 7 Ne- 1 7 N mirror pair.