Apollo took about an hour to pass through the worst part of the radiation belts. The total radiation dose received by the astronauts was about one rem. The Van Allen Radiation Belts consist of a doughnut-shaped region centered on Earth's magnetic equator. The translunar trajectories followed by the Apollo spacecraft were typically inclined about 30 degrees to Earth's equator, therefore Apollo bypassed all but the edges of the radiation belts. http://www.braeunig.us/apollo/VABraddose.htm
Be Thankful For the Invisible Belt That Saves Earth From Radiation
Well, here's something cosmic to be thankful for this weekend. A NASA-led study of the Van Allen radiation belts has uncovered new information about the invisible "shield" that keeps harmful ultrarelativistic electrons from the Earth. Credit: Nature - http://www.nature.com/nature/journal/v515/n7528/full/nature13956.html and MIT News - https://newsoffice.mit.edu/2014/plasma-shield-against-harmful-radiation-1126
Invisible shield found thousands of miles above Earth blocks 'killer electrons'
An invisible shield has been discovered some 7,200 miles above Earth that blocks so-called 'killer electrons,' which whip around the planet at near-light speed and have been known to threaten astronauts, fry satellites and degrade space systems during intense solar storms.
The Apollo 11 mission's computers were less powerful than today's mobile phones By Brian Burke on July 15, "It's absolutely amazing that the computers used to guide the Apollo 11 mission to the moon were no more powerful than a pocket calculator or a mobile phone."