Modern External Beam Radiotherapy Techniques - Intensity Modulated Radiotherapy

External beam radiotherapy is a complex cancer radiotherapy technique involving three-dimensional conformal and intensity-modulated radiation therapy high-energy X-ray beam delivery to tumour volumes where dose distributions and treatment plan optimisation, including inverse planning, are applied. Examples of clinical treatment plans using 3D conformal and intensity-modulated radiotherapy techniques for patients with tumours located in the regions of head and neck (right tonsil carcinoma) and pelvis (prostate) were evaluated and compared. An intensity-modulated radiotherapy plan for a patient with arm cancer, untreatable with the 3D conformal radiation therapy technique, is also presented. Comparison of dose distributions showed that with the intensity-modulated radiotherapy technique dose homogeneity within the target volume was improved and dose to normal tissues and organ-at-risk structures reduced. Significant reductions in the mean and maximum doses to the spinal cord (head and neck) and rectum (prostate) were also achieved. Due to the geometrical issues, in all patients, improvement in dose distribution was evident with the intensity-modulated radiotherapy technique, especially for concave dose distributions.