Hi squiggiez, and welcome to cruise-chat.com!
Depending upon the port, you should be able to bring a carry-on aboard. It needs to fit through the screening machine, which is similar to those found on the security line in airports. We usually give our large bags to the porters and carry on a bag with medications and other items that must be with us, as well as a small rollaboard that has essential clothing that is not easily replaced.
From which port are you departing?