RESUMEN
The evaluation of possible improvement in the use of Gd in cancer therapy, in reference to gadolinium in cancer therapy (GdNCT), has been analysed. At first the problem of the gadolinium compounds toxicity was reviewed identifying the Motexafin Gadolinium as the best. Afterwards, the spectrum of IC and Auger electrons was calculated using a special method. Afterwards, this electron source has been used as input of the PENELOPE code and the energy deposit in DNA was well defined. Taking into account that the electron yield and energy distribution are related to the neutron beam spectrum and intensity, the shaping assembly architecture was optimised through computational investigations. Finally the study of GdNCT was performed from two different points of view: macrodosimetry using MCNPX, with calculation of absorbed doses both in tumour and healthy tissues, and microdosimetry using PENELOPE, with the determination of electron RBE through the energy deposit. The equivalent doses were determined combining these two kinds of data, introducing specific figures of merit to be used in treatment planning system (TPS). According to these results, the GdNCT appears to be a fairly possible tumour therapy.
Asunto(s)
Gadolinio/uso terapéutico , Neoplasias/radioterapia , Terapia por Captura de Neutrón/métodos , Fármacos Sensibilizantes a Radiaciones/uso terapéutico , Gadolinio/farmacocinética , Gadolinio/toxicidad , Humanos , Isótopos/farmacocinética , Isótopos/uso terapéutico , Isótopos/toxicidad , Método de Montecarlo , Terapia por Captura de Neutrón/estadística & datos numéricos , Terapia por Captura de Neutrón/tendencias , Fármacos Sensibilizantes a Radiaciones/farmacocinética , Fármacos Sensibilizantes a Radiaciones/toxicidad , Planificación de la Radioterapia Asistida por Computador/estadística & datos numéricosRESUMEN
A thorough evaluation of the dose inside a specially designed and built facility for extra-corporeal treatment of liver cancer by boron neutron capture therapy (BNCT) at the High Flux Reactor (HFR) Petten (The Netherlands) is the necessary step before animal studies can start. The absorbed doses are measured by means of gel dosemeters, which help to validate the Monte Carlo simulations of the spheroidal liver holder that will contain the human liver for irradiation with an epithermal neutron beam. These dosemeters allow imaging of the dose due to gammas and to the charged particles produced by the (10)B reaction. The thermal neutron flux is extrapolated from the boron dose images and compared to that obtained by the calculations. As an additional reference, Au, Cu and Mn foil measurements are performed. All results appear consistent with the calculations and confirm that the BNCT liver facility is able to provide an almost homogeneous thermal neutron distribution in the liver, which is a requirement for a successful treatment of liver metastases.
Asunto(s)
Terapia por Captura de Neutrón de Boro/instrumentación , Geles/efectos de la radiación , Neoplasias Hepáticas/radioterapia , Neutrones , Radiometría/instrumentación , Planificación de la Radioterapia Asistida por Computador/instrumentación , Terapia por Captura de Neutrón de Boro/métodos , Diseño de Equipo , Análisis de Falla de Equipo , Humanos , Italia , Radiometría/métodos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
The idea to couple the treatment planning system (TPS) to the information on the real boron distribution in the patient acquired by positron emission tomography (PET) is the main added value of the new methodology set-up at DIMNP (Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione) of University of Pisa, in collaboration with the JRC (Joint Research Centre) at Petten (NL). This methodology has been implemented in a new TPS, called Boron Distribution Treatment Planning System (BDTPS), which takes into account the actual boron distribution in the patient's organ, as opposed to other TPSs used in BNCT that assume an ideal uniform boron distribution. BDTPS is based on the Monte Carlo technique and has been experimentally validated comparing the computed main parameters (thermal neutron flux, boron dose, etc.) to those measured during the irradiation of an ad hoc designed phantom (HEterogeneous BOron phantoM, HEBOM). The results are also in good agreement with those obtained by the standard TPS SERA and by reference calculations carried out using an analytical model with the MCNP code. In this paper, the methodology followed for both the experimental and the computational validation of BDTPS is described.