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

Abstract

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 y; range, 20 months to 5 y) were treated with IMRT using volumes accounting for physiologic motion (IMRT_phys) and daily pretreatment cone beam CT 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 (PTV) from 668.8 ± 200.6 cc to 393.0 ± 132.5 cc (p < 0.001) and reduced mean body V50 from 1774.4 ± 383.9 cc to 1385.7 ± 365.7 cc (p < 0.001). The IMRT_phys plan reduced the percent mean dose to the ipsilateral kidney from 70.1% ± 4.3% to 66.0% ± 5.2% (p = 0.002); that to the contralateral kidney was reduced from 56.3% ± 7.0% to 40.7% ± 9.5% (p < 0.001), and that to the liver was reduced from 57.8% ± 16.0% to 22.1% ± 6.8% (p = 0.001). Conclusions For IMRT planning, ICRU 62–compliant volume definition with image guidance in the pediatric abdomen enables volumetric reduction of the PTV and reduces normal tissue dose. These methods provide a framework for more conformal treatment planning in the pediatric abdomen.

Intensity modulated radiation therapy provides excellent local control in high‐risk abdominal neuroblastoma

“…The limited follow‐up of 2 years in our study was sufficient to obtain reasonable estimates of local control and is consistent with the median time to local failure in high‐risk NB of 2 years or less in previous studies 6, 7, 14. Despite the retrospective nature of these data, the methods and techniques were homogeneously employed in this cohort of children, and show the benefit of highly conformal therapy in patients with high‐risk abdominal NB 12. This regimen has been concurrently developed into a prospective study evaluating applicability to highly conformal therapy with protons 11.…”

“…Two children received 36 Gy, in accordance with new protocol guidelines requiring dose escalation for GRD. With the overall aim of assessing locoregional control, all patients were treated consistently using reproducible immobilization techniques; physiological motion was assessed by 4D-CT, and target localization by cone beam CT [11,12]. Figure 1 shows axial (A), coronal, (B) ipsilateral renal (C), and contralateral renal (D) dosimetric images of a 4-year-old patient with locally invasive right adrenal primary high-risk NB with MYCN amplification.…”

“…Figure 1 shows axial (A), coronal, (B) ipsilateral renal (C), and contralateral renal (D) dosimetric images of a 4-year-old patient with locally invasive right adrenal primary high-risk NB with MYCN amplification. A plan employing ICRU 62 conventions developed for IMRT on the basis of previously published data for pediatric abdominal target volume and organ motion was used for all patients [9,10,12].…”

Can We Spare the Pancreas and Other Abdominal Organs at Risk? A Comparison of Conformal Radiotherapy, Helical Tomotherapy and Proton Beam Therapy in Pediatric Irradiation

“…Both organ and target motion is a key issue in IMRT/PBT and image-guided radiation therapy to the upper abdomen. In a study of eight children with high-risk neuroblastoma, IMRT planning with volume definition based on image guidance (4-D CT and MRI fusion) enabled volumetric reduction of the PTV and a reduced dose to normal tissue compared to IMRT planning with conventional volumetric construction [ 32 ].…”

Reassessing dose constraints of organs at risk in children with abdominal neuroblastoma treated with definitive radiation therapy: A correlation with late toxicity

“…Equally important is the accurate characterization of RT dose-volume constraints and toxicity risk specific to the kidney(s) and liver, which represent the primary OARs constrained in RT planning. As demonstrated in Tables II and V [9,15,17,[19][20][21][22][23], there remains significant variability in OAR constraint parameters across recent protocols and institutions. These constraints appreciably influence the delivery and design of RT, yet are not based on toxicity data specific to children with neuroblastoma.…”