3D-personalized Monte Carlo dosimetry

Some of these articles get rather technical, But I think it is indicative of the ongoing research in finding better methods of using SIRT technology . The Journal of Nuclear Medicine  can be a good source for some of the leading edge research being performed around the world. Anything that improves the outcome is good for the poor soul with the cancer and good for SRX - a win - win.

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http://jnm.snmjournals.org/content/...id=1&usestrictdates=yes&resourcetype=HWCIT&ct
3D-personalized Monte Carlo dosimetry for treatment planning optimization in SIRT

1. Alice Petitguillaume1,
2. Michela Bernardini2,
3. Claire De Labriolle-Vaylet3,
4. Didier Franck1 and
5. Aurelie Desbrée1

+ Author Affiliations

1. 1IRSN, Fontenay-aux-roses, France
2. 2HEGP, Paris, France
3. 3Hôpital Trousseau, Paris, France

Abstract

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Objectives The 3D-Personalized Monte Carlo Dosimetry (PMCD) was developed for treatment planning in nuclear medicine and applied to the Selective Internal Radiation Therapy (SIRT), in which 90Y-microspheres are injected to the patient.
Methods The PMCD was evaluated for 20 patients treated for hepatic cancers at Hôpital Européen Georges Pompidou (HEGP). First, regions of interest were outlined on the patient CT scan. Using the OEDIPE software, patient-specific voxel phantoms were created. 99mTc-MAA SPECT data were then used to generate 3D-matrices of cumulated activity. Absorbed dose (D) and Biologically Effective Dose (BED) were calculated at the voxel scale using the MCNPX Monte Carlo transport code. Finally, OEDIPE was used to determine the maximum injectable activity (MIA) for tolerance criteria on organs at risk (OARs), i.e. the lungs and non tumoral liver. Tolerance criteria based on mean D, mean BED, Dose-Volume Histograms (DVHs) or BED-Volume Histograms (BVHs) were considered. Those MIAs were compared to the ones recommended by the Body Surface Area (BSA) method and the Partition Model, which are the conventional methods used in clinical practice.
Results Compared to BSA method and Partition Model recommendations, performing dosimetry using the PMCD enables to adjust the activity prescription depending on the OARs irradiation. Moreover, tolerance criteria based on DVHs allow enhancing treatment planning efficiency by taking advantage of the fact that OARs are parallel organs. Finally, tolerance criteria on mean BED and BVHs were used to consider fractionated protocols, going further in the dose optimization by taking into account biological considerations such as cell repair or radiosensibility.
Conclusions Besides its applicability in clinical routine, the interest of a personalized Monte Carlo dosimetry for treatment planning in SIRT was confirmed from those patient studies. Finally, the PMCD is a general purpose method that could be used to optimize treatment planning and dosimetry for different molecular radiotherapies.