Whole-body dosimetry for individualized treatment planning of 131I-MIBG radionuclide therapy for neuroblastoma.
The aims of this study were to examine the relationship between whole-body absorbed dose and hematologic toxicity and to assess the most accurate method of delivering a prescribed whole-body absorbed dose in (131)I-metaiodobenzylguanidine ((131)I-MIBG) therapy for neuroblastoma.


METHODS
A total of 20 children (1-12 y), 5 adolescents (13-17 y), and 1 adult (20 y) with stage 3 or 4 neuroblastoma were treated to a prescribed whole-body absorbed dose, which in most cases was 2 Gy. Forty-eight administrations of (131)I-MIBG were given to the 26 patients, ranging in activity from 1,759 to 32,871 MBq. For 30 administrations, sufficient data were available to assess the effect of whole-body absorbed dose on hematologic toxicity. Comparisons were made between the accuracy with which a whole-body absorbed dose could be predicted using a pretherapy tracer study and the patient's most recent previous therapy. The whole-body absorbed dose that would have been delivered if the administered activity was fixed (7,400 MBq) or determined using a weight-based formula (444 MBq.kg(-1)) was also estimated.


RESULTS
The mean whole-body absorbed dose for patients with grade 4 Common Terminology Criteria for Adverse Events (CTCAE) neutropenia after therapy was significantly higher than for those with grade 1 CTCAE neutropenia (1.63 vs. 0.90 Gy; P = 0.05). There was no correlation between administered activity and hematologic toxicity. Absorbed whole-body doses predicted from previous therapies were within +/-10% for 70% of the cases. Fixed-activity administrations gave the largest range in whole-body absorbed dose (0.30-3.11 Gy).


CONCLUSIONS
The results indicate that even in a highly heterogeneous and heavily pretreated patient population, a whole-body absorbed dose can be prescribed accurately and is a more accurate predictor of hematologic toxicity than is administered activity. Therefore, a whole-body absorbed dose can be used to deliver accurate and reproducible (131)I-MIBG therapy on a patient-specific basis.
Buckley
Susan E
SE
Department of Physics, Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom.
Chittenden
Sarah J
SJ
Saran
Frank H
FH
Meller
Simon T
ST
Flux
Glenn D
GD
D019797:3-Iodobenzylguanidine / Q000627:therapeutic use*; D000293:Adolescent; D001822:Body Burden; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009447:Neuroblastoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014915:Whole-Body Counting / Q000379:methods*; D055815:Young Adult
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine