Radiotherapy and the flu jab

As the title asks shouldi get the flu jab if starting radiotherapy to the skin. This will start on one area first then total body skin radiotherapy. I was not told any information on this subject at the hospital and was just thinking about it. I have never had the flu jab before and avoided it as so many others over the last few years i know were feeling very flu ish after getting the jab. 

Thanks in advance for taking the time to read or possibly responding.