Standard indicators of the quality of cancer radiotherapy treatment not only includes accuracy of treatment process, but also the patient wait time to go under treatment. A common cause of anxiety for patients who are diagnosed with cancer and prescribed for radiation therapy is how long they should wait for their radiation sessions to begin. This waiting time estimation either remains unclear or is longer than it is originally planned. One of the major attempts for radiotherapy cancer centers to improve their quality of services is to try to keep the patient waiting time under control and as low as reasonably possible. In this paper, the aim is to understand the magnitude of bottlenecking in the fundamental steps of the radiation therapy treatment process in order to simulate a model that can be used further on by cancer centers to develop their quality program. The result of this optimal simulation model would be a reduction of the delay between the time that the oncology recommends a patient for undergoing radiotherapy and the time that patients actually starts the radiation treatment sessions.