We're now told that the technology required to transit the Van Allen Radiation Belts and go 238k to the moon and back has been lost to NASA via accidental destruction. The modern spacecraft Orion is now designed specifically to have the equivalent of six feet of lead shielding--like nothing Apollo had--to allow for safe human transit.
I explain it away as pictures of mock-ups. I made a few conceptual models myself back in the day. You have to remember this is back before CAD, back when the nation had real draftsmen. This thing was obviously very complex. It was the way we did things back in the day. I’ve personally seen several different style water and wind tunnels. They worked.
Transit time through the VAB zone was quite brief for the Apollo missions. We actually have fairly good data on VAB exposure rates, going back to the Gemini 10 flight, which was the first manned spacecraft to penetrate a portion of the Van Allen belts (the South Atlantic Anomaly). Maximum mission duration for Apollo was in the range of 12 days (Apollo 17 made it to 12 days, 14 hours). Of more concern for long-duration missions is primary cosmic radiation. There is some thought of using Orion for long-duration flights, either to Mars or an asteroid, so shielding for that kind of spacecraft would likely be heavier than needed for the relatively short-duration lunar missions. Shielding against primary cosmic radiation (primarily high-energy protons) is challenging because exposure comes from secondary reactions in the shielding itself (sometimes called build-up). The newer shielding is probably some compositte material that provides protection against the primary particles while minimizing secondary emissions.