I completed 33 radiation treatments to my neck in June. I worked most of the time. I left about an hour early each day to go get my treatment. I found that I got a little tired towards afternoon but only rarely did I feel like I really needed to go home and nap.
The month after the radiation was worse for me than the radiation. I had some very tired days that would hit around noon, lost my voice for 2 days, light headedness and rash... these all occured starting about a week after it was all over. Keep in mind, this was neck radiation.
I had a co-worker who had breast radiation and she worked all through her radiation ... about 3/4 days. She went for treatment in the am. Her only problem was the sunburn. Ask if you can trial sample a few creams before you start. Silvadene actually caused me to break down more. I got some called Rad X online ... it was kind of pricey, but I think it helped and I used it from the start. If you trial a few on other parts of your body, you might avoid a bad reaction.
Looking back, it really wan't all that bad. It is a scary stressful thing to go through, but you will get through.