ABSTRACT
Radiotherapy of the posterior fossa is routinely delivered using 3DCRT parallel-opposed lateral fields. However high incidence of sensorineural hearing loss, hypothalamic pituitary dysfunction, thyroid and gonadal dysfunction during radiotherapy makes the need for treatment plan which provides adequate coverage of the target volume while sparing of the cochlea and other surrounding organs at risk [OARs] at same time inevitable. To compare the coverage of posterior fossa and the dose to surrounding OARs including non-posterior fossa brain, pituitary, cochlea, eyes, optic nerves, optic chiasm, cervical spinal cord, thyroid gland, pharynx, parotid glands and mandible using three different 3DCRT plans. Ten patients underwent CT simulation for treatment planning of posterior fossa boost. The CT data were transferred to Precise Elekta treatment planning system where posterior fossa, non-posterior fossa brain, pituitary, cochlea, parotid glands, cervical spinal cord, thyroid gland, pharynx, mandible, eyes, lenses, optic nerves and optic chiasm were all contoured. For each patient, three plans were carried out; two parallel opposed open lateral photon fields, a pair of wedged posterior oblique fields, and a pair of wedged posterior oblique fields and an open vertex field