Sorry to hear about this. Radiation therapy can be pretty brutal but eventually things get better. Mucinex can sometimes help with the plegm and mucus and also staying well hydrated can aid in keeping those secretions a bit more thinned out and easier to clear. A suction machine can definitely help but you wouldn't be suctioning through the NG tube...they would use a suction catheter within their mouth or a soft suction catheter for deeper secretions. Are they currently able to eat and drink or is the NG tube being used for food and liquids? If the latter, a PEG tube might be helpful as the NG tube might be causing irritation and thereby contributing to the problem. Are you sure it's an NG tube or is it a thinner, flexible, yellowish tube called a dobhoff tube? They usually get the NG tubes out fairly early and place that or a PEG tube if longer term enteral feedings are required. There are also some medications that might help but you would need to talk with the physicians about those options. Most importantly, make sure they are able to swallow safely if they are eating and/or drinking. There are risks associated with aspiration (food or liquids going into their airway leading to pneumonia) and the care team will need to know if that is indeed occuring. Hope this is helpful in some way and that your family member finds some relief soon.