The Role for intensity modulated radiation therapy (IMRT) in pediatric population.

The purpose of this study was to evaluate our initial experience on the use of IMRT in children with tumors in eloquent or critical locations. Twenty-two children with a median age of 12 years (range 1-17) were treated using IMRT for tumors which were within 2 cm of a critical structure. The treatment locations were spine [2], head and neck [5], abdominopelvic [8], and intracranial [7]. Eighty-two percent (82%) of patients were treated with curative intent despite most patients having advanced or metastatic disease and two patients having previously received standard external beam radiation. IMRT was delivered with a 6MV linear accelerator using dynamic multileaf collimators with a median of six fields. The median follow-up was five months [1-21]. The median administered dose was 45 Gy. The median planning treatment volume (PTV) was 105.4 cc. For the intracranial lesions, the mean doses to the pituitary, brainstem, cochlea, optic nerve, and lens were 31%, 42%, 17%, 27%, and 6% of the total dose, respectively. For the head and neck tumors, the mean doses to the spinal cord and parotid glands were 47% and 49%, respectively. For the pelvic tumors, the mean dose to the bladder, rectum, and small bowel were 51%, 63%, and 22%, respectively. Local failure occurred in one patient. IMRT resulted in substantial sparing of surrounding critical structures and acceptable local control rate for these tumors in children. Further follow-up is needed to assess long-term local control and late effects.