Does radiation still work through the johnny shirt?

Of course it works. My facility had nice heavy-weight cotton wrap robes, and they only opened them to line up the marks and beams, then covered me again before zapping. They've been doing this a LONG time, remember. Its new for you, but not them.

After I was lined up they covered me back up.

I was never covered up but they otherwise mummified me in a heated blanket...only the radiated part exposed. It was actually kind of relaxing in a weird way.

Star111---you know, I did feel effects right away. The same day I got a little swollen and pink, I guess some sort of inflammatory reaction? They told me it was impossible (which makes me think it's rare), but well, it was obvious with no other cause or explanation. I also felt a little "cooked" inside, almost like heartburn but in my breast. Could have been my wild imagination mixed with anxiety. Very possible. Anyway, it stayed like that for a couple of days and then calmed down. I didn't get the "sunburn" until about, I don't know, 2-3 weeks in. Only other side effects were a low grade scratchy throat for the entire 6 weeks, and fatigue that would hit come Friday. Well, there was the skin drama, but I ended up being allergic to the radiation lotion after about 3 weeks of using it. Most people don't experience that I believe. My skin had to be "extra." :-)

I would think it would go through the shirt....I think the radiation beam is pretty darn strong!

I wasn't covered either. Cocooned in warm blankets and my breast to be radiated fully exposed. I was very fortunate, I had little tanning, and my nipple is darker, that's it. Finished two weeks ago.

I was uncovered only in the area that was being radiated. If it makes you feel any more at ease, they covered the chest wall with a Bolus ( kinda like a gel cooling pack) after I was lined up. Way thicker than fabric. and I most definitely got the radiation though it considering the burns I got ( which weren't terrible but I got them) . Honestly I wouldn't worry about the Johnny coat. Like others have said, they've been doing it a long time, and if there was an issue with it, it wouldn't be happening. I've had X-rays fully clothed or in a Johnny coat. And you'll notice when techs have to be in the room for any radiation procedure, they're covered in lead garments . I think you're good