Intent of treatment. Intent of treatment and dose fractionation. Intent of treatment is palliative or curative. Dose fractionation means how big of a dose over what period is given. For example in cyberknife steriotactic body radiotherapy we can deliver radiation over 3-4 days to cure early stage lung cancer. With smaller dose/ fraction it takes about 7weeks of radiation to cure. 2-4 weeks of radiation for palliation.
For Palliation. We treat cancer for cure or palliation (releive a symptom). Its usually 2 to 2 and 1/2 weeks for pallliation and for cure its usually 5 to 7 weeks depending on type of lung cancer. So am not sure why only a month or 4 weeks unless the doctor was trying to do a better job in palliation or was just dragging it out for another reason. I would definitely ask my doctor though knowing the info i gave.
Treatment Intent. There are case treated with curative intent, and some of these are ultra-short, and others that are treated to relieve a symptom. For many years the duration of treatment has moved from 6 - 8 weeks. Short course/ high dose/fraction radiotherapy is quite effective, but it cannot be used to big fields.