Cervical cancer is a gynecological diseases that has a fairly high malignancy. One of the treatments for cervical cancer can be done with radiation therapy or radiotherapy. Radiotherapy begins with a radiation simulation by using a diagnostic device from the results of the image produced, then planning will be carried out in the stage of Treatment Planning System (TPS).In the radiotherapy positioning of patients and the use of fixation devices is very important, which is generally used namely the baseplate.Thus, in the Radiotherapy Installation of Dr. RSUP Hasan Sadikin the fixation tool used is a combination of the baseplate and four point of thermoplastic mask. The aims of this study is to learn more about theexternal radiotherapy management of cervical cancer with the fixation of thermoplastics in the Radiotherapy Installation of RSUP Dr. Hasan Sadikin.This study uses qualitative research with case studies. The object of research was cervical cancer patients who used four-point thermoplastic mask fixation tool. The research subjects were Oncologists, Medical Physicists, Radiographers and patients. The data was collected by observation, interviews and documentation. The data analysis was conducted with interactive model of Milles and Huberman.The result of research showed that the external radiotherapy of cervical cancer in the Radiotherapy Installation of RSUP Dr. Hasan Sadikin has been done using the simulation stage, TPS calculation, verification, and irradiation. The use of four-point thermoplastic mask fixation tool is to entering four-point thermoplastic mask into a water tank with a temperature65oCuntil it turns transparent, then attached to the patient's body, especially in the radiation area, pulls the hook on the thermoplastic mask and then locks it. After that, let stand for a moment until the thermoplastic mask becomes hard and cold. So, the reason that the shift in the target object obtained is likely to be small or even non-existent, from the view of the radiation oncologist in the use of thermoplastic masks that it is very necessary for any examination. Thus, in terms of aesthetic value is better, because the sign radiation area is not drawn by directly on the patient's body but it is drawn on the thermoplastic mask.