Dear Pizmo9, Treatment for cancer can put you at increased risk for conditions such as pneumonia. The decision as to when to resume radiation therapy should be be made in consultation with your radiation oncologist who will advise based on your overall clinical condition.
I am not a doctor but I have Googled your question and this is what I found:
"Pneumonia in children and adults is caused by bacteria, virus, fungi or protozoa. Out of these, bacteria are the most common microorganisms, that have been found to cause pneumonia. These microorganisms usually enter the body through mouth, nose and eyes, and then infect the lungs, especially the air sacs or alveoli of the lungs. Pneumonia is more commonly found to affect the lower lobes of the lungs. Apart from microorganisms, pneumonia can also be caused by any injury or damage to the lungs, caused by the exposure to certain chemicals and radiation. So, many times, people receiving aspiration or radiation therapy can too get pneumonia". This is the link:
http://www.buzzle.com/articles/acute-pneumonia.html
It is your doctor or Radiotherapist who should say what you are to do now, if you continue with radiation while on meds for pneumonia or if you do something else. Said doctors are the only ones who should tell you what to do. Please don't make any decisions on your own.
Take care and get well.