Validation of a new method for dose determination in radiosurgery: “The Sosa Model”
Validation of a new method for dose determination in radiosurgery: “The Sosa Model”
Date
2024-04-04
Authors
Santiago Valenzuela Sosa
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Abstract
Goals: to demonstrate the validity of the XYZ Geo Method of rapid indirect volumetry
37, 38, 39 using the simplified geometric formula of the XYZ/1910 ellipsoid, to obtain
a volume of the anterior part of the hippocampus (Ammon’s Horn + Body = AA) or the
complete Hippocampus, including the tail (AA + Tail = Complete Hippocampus = HarP
= Harmonized Protocol 24), very close to the real volume determined by the voxel method
(planimetry). Material and Method: prospective study, which took place between January
2020 and July 2022, of 100 Dominican adults, divided into a control group of 60 patients
with normal cognition divided into 3 age groups (20-40, 41 to 60 and 61 to 80 years). and
a case group of 40 patients complaining of cognitive problems (aged 41 to 60 and 61 to
80). The Folstein Mini Mental State Examination (MMSE) adapted to Latino patients
was administered.15. All benefited from a 1.5 Tesla MRI with 1-1.5 mm slices for three-
dimensional reconstruction including non-contrast T1, FLAIR, T2 and TOF sequences.
The Principal Investigator (PI) performs real volumetry of the Anterior and Complete
Hippocampus using voxels (planimetry), processing these Magnetic Resonance images on
the Elekta Workstation Gamma Plan 10 platform of the Dominican Gamma Knife Center
of CEDIMAT in the Plaza de la Salud de Santo Sunday, Dominican Republic. Next, the PI
performs the indirect volumetry of these structures by applying the simplified formula of the
Ellipsoid, following the guidelines of the XYZ Geo Method for rapid indirect volumetry
of intracranial structures39, determining their largest diameters Axial (X), Sagittal (Y)
and Vertical (Z) on the aforementioned Platform. For each of these patients, blindly with
respect to the PI results, the Research Assistants (RA), using the Magnetic Resonance CD
in which the RadiAnt DICOM Viewer software with capacity for millimeter measurement
is encrypted, determine rapid indirect volumetry of the Anterior Hippocampus (AA)
and complete Hippocampus (HarP) applying the aforementioned methodology. The data
collected was processed using measures of central tendency and dispersion in the Microsoft
Excel 2016 platform. Results: The indirect volumetry of the hippocampi studied carried out by
the PI using the simplified geometric formula of the ellipsoid had an average approximation
of 101.7% with respect to the real volume determined by voxels. The measurement carried out by the RAs approached 99.6% of the real volume of the hippocampi studied. The average
time to perform the actual volumetry of the Anterior Hippocampus (AA) by the PI was
more than 11 minutes, while using the formula for rapid indirect volumetry the hippocampal
volume could be calculated in less than a minute. Conclusion: indirect volumetry of the
hippocampus applying the guidelines of the XYZ Geo Method 39 and using the simplified
geometric formula of the ellipsoid, it is a reliable and rapid alternative to determine the
health and integrity of this important anatomical marker of cognitive and seizure health,
even if it is used by non-neurospecialist doctors.
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Citation
Valenzuela Sosa, S. (2024). Rapid indirect hippocampal volumetry using the XYZ GEO method: A useful tool in the diagnosis of cognitive impairment. Universidad Autónoma de Santo Domingo (UASD).