Patient-specific dosimetry for intracavitary 32P-chromic phosphate colloid therapy of cystic brain tumours.
Eur J Nucl Med Mol Imaging
; 40(10): 1532-41, 2013 Oct.
Article
em En
| MEDLINE
| ID: mdl-23740370
ABSTRACT
PURPOSE:
(32)P-chromic phosphate colloid treatments of astrocytoma and craniopharyngioma cystic brain tumours in paediatric patients are conventionally based on a sphere model under the assumption of uniform uptake. The aims of this study were to determine the distribution of the absorbed dose delivered by (32)P on a patient-specific basis and to evaluate the accuracy with which this can be predicted from a pretherapy administration of (99m)Tc-Sn colloid.METHODS:
Three patients were treated with (32)P-chromic phosphate colloid following (99m)Tc-Sn colloid administrations. Convolution dosimetry was performed using pretherapy and posttherapy sequential SPECT imaging, and verified with EGSnrc Monte Carlo radiation transport simulations. Mean absorbed doses to the cyst wall and dose-volume histograms were also calculated and compared with those obtained by the sphere model approach.RESULTS:
Highly nonuniform uptake distributions of both the (99m)Tc and (32)P colloids were observed and characterized by dose-volume histograms to the cyst wall. Mean absorbed doses delivered to the cyst wall, obtained with the convolution method, were on average 21 % (SD 18 %) and 50 % (SD 30 %) lower than those predicted by the (99m)Tc distribution and the uniform assumption of the sphere model, respectively.CONCLUSION:
Absorbed doses delivered to the cyst wall by (32)P are more accurately predicted from image-based patient-specific convolution dosimetry than from simple sphere models. These results indicate the necessity to perform personalized treatment planning and verification for intracavitary irradiation of cystic brain tumours treated with radiocolloids. Patient-specific dosimetry can be used to guide the frequency and levels of repeated administrations and would facilitate data collection and comparison to support the multicentre trials necessary to progress this therapy.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfatos
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Neoplasias Hipofisárias
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Radiometria
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Astrocitoma
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Neoplasias Encefálicas
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Compostos de Cromo
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Compostos Radiofarmacêuticos
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Craniofaringioma
Tipo de estudo:
Prognostic_studies
Limite:
Child
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Female
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Humans
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Male
Idioma:
En
Revista:
Eur J Nucl Med Mol Imaging
Assunto da revista:
MEDICINA NUCLEAR
Ano de publicação:
2013
Tipo de documento:
Article