With the progress of technology, radiation oncology graduated from a 2 dimensional to a 3 dimensional approach. This type of external beam radiation planning takes into account the 3 dimensional information of a cancerous tumour. This means that it assesses the tumour’s volume and the organs around it that are at risk. Treatment planning is conducted using the CT simulation of the patient in a particular position with certain immobilisation devices. After this stage, the images are shifted to a planning station where the tumour is marked apart from other organs at risk. Finally the dose is prescribed by a radiation oncologist. The entire process is carried out via a computer and a plan is made appropriately to deliver the treatment to the patient.