Methods for image guided and intensity modulated radiation therapy in high-risk abdominal neuroblastoma.

PURPOSE

Our purpose was to determine methods for image guided intensity modulated radiation therapy (IMRT) in pediatric abdominal high-risk neuroblastoma and to quantify the degree of normal tissue dose reduction by using volumes compliant with International Commission on Radiation Units and Measurements (ICRU) Report 62.

METHODS AND MATERIALS

Eight consecutive children with high-risk abdominal neuroblastoma (median age, 2.5 years; range, 20 months-5 years) were treated with IMRT using volumes accounting for physiologic motion (IMRT_phys) and daily pretreatment cone beam computed tomographic localization. Comparative IMRT planning using conventional volumes (IMRT_std) provided quantification for dose reduction to normal tissues.

RESULTS

The IMRT_phys plan reduced the mean planning target volume from 668.8 ± 200.6 cc to 393.0 ± 132.5 cc (P < .001) and reduced mean body V50 from 1774.4 ± 383.9 cc to 1385.7 ± 365.7 cc (P < .001). The IMRT_phys plan reduced the percent mean dose to the ipsilateral kidney from 70.1% ± 4.3% to 66.0% ± 5.2% (P =.002); that to the contralateral kidney was reduced from 56.3% ± 7.0% to 40.7% ± 9.5% (P < .001), and that to the liver was reduced from 57.8% ± 16.0% to 22.1% ± 6.8% (P = .001).

CONCLUSIONS

For IMRT planning, ICRU 62-compliant volume definition with image guidance in the pediatric abdomen enables volumetric reduction of the planning target volume and reduces normal tissue dose. These methods provide a framework for more conformal treatment planning in the pediatric abdomen.