K. Hopkins et al., A MODEL TO ESTIMATE THE DOSE TO TUMOR FOLLOWING INTRACAVITY ADMINISTRATION OF RADIOIMMUNOCONJUGATES TO PATIENTS WITH MALIGNANT GLIOMAS, British journal of radiology, 70(839), 1997, pp. 1152-1161
Patients who have relapsed following primary treatment for malignant g
lioma and have undergone further surgical debulking have been treated
with an anti-human neural cell adhesion molecule (NCAM) MoAb linked to
either Iodine-131 or Yttrium-90. These reagents are introduced into t
he tumour resection cavity via an Ommaya reservoir. Pharmacokinetic an
d imaging studies indicate that the radioimmunoconjugate remains withi
n the cavity for a protracted period of time. In this manuscript we de
velop a dosimetric model to predict the dose delivered to the rim of t
issue surrounding the resection cavity. The model takes into account v
ariables such as the diameter of the cavity and the degree of antibody
binding which is achieved. Whilst the calculated doses to the wall of
the cavity are relatively inaccurate due to our inability to measure
factors such as diffusion and heterogeneity in antibody uptake, the mo
del illustrates the potential benefits and pitfalls that can result fr
om targeting the two radionuclides. It is hoped that as increasing int
erest is shown in this type of ''liquid brachytherapy'' other groups w
ill find it useful to apply the model to allow comparisons to be made
between our targeting strategy and those developed by other individual
s.