CIL 6.1284-1285 – Metrical epitaph on a sarcophagus for Lucius Cornelius Scipio Barbatus

Photographs and translation

CIL 6.1286 – Metrical epitaph for Lucius Cornelius Scipio, son of Barbatus

Photograph

CIL 6.1287 – Metrical epitaph for Lucius Cornelius Scipio, son of Barbatus

Photographs, notes by A.E. Gordon, and translation by A.J. Heisserer

CIL 6.1288 – Metrical epitaph for Publius Cornelius Scipio, son of Publius

Photograph and notes by A.E. Gordon

CIL 6.1289 (bottom) + 6.1294 (top) – Metrical epitaph for Lucius Cornelius Scipio, son of Gnaeus, grandson of Gnaeus

Photograph and notes by A.E. Gordon

CIL 3.7234 – Inscribed base for equestrian (?) statue for L. Cornelius Sulla

Photographs and notes by A.E. Gordon

CIL 3.7235 – Inscribed statue base for L. Cornelius Sulla

Photograph and notes by A.E. Gordon

CIL 3.14147.5 – Trilingual dedication to the dei patriei and the Nile by C. Cornelius Gallus, first prefect of Egypt

Photographs and notes by A.E. Gordon

Commissioning of a Geant4 based treatment plan simulation tool : linac model and dicom-rt interface

A Geant4 based simulation tool has been developed to perform Monte Carlo modelling of a 6 MV VarianTM iX clinac. The computer aided design interface of Geant4 was used to accurately model the LINAC components, including the Millenium multi-leaf collimators (MLCs). The simulation tool was verified via simulation of standard commissioning dosimetry data acquired with an ionisation chamber in a water phantom. Verification of the MLC model was achieved by simulation of leaf leakage measurements performed using GafchromicTM film in a solid water phantom. An absolute dose calibration capability was added by including a virtual monitor chamber into the simulation. Furthermore, a DICOM-RT interface was integrated with the application to allow the simulation of treatment plans in radiotherapy. The ability of the simulation tool to accurately model leaf movements and doses at each control point was verified by simulation of a widely used intensity-modulated radiation therapy (IMRT) quality assurance (QA) technique, the chair test.

Fast tessellated solid navigation in GEANT4

Navigation through tessellated solids in GEANT4 can degrade computational performance, especially if the tessellated solid is large and is comprised of many facets. Redefining a tessellated solid as a mesh of tetrahedra is common in other computational techniques such as finite element analysis as computations need only consider local tetrahedrons rather than the tessellated solid as a whole. Here within we describe a technique that allows for automatic tetrahedral meshing of tessellated solids in GEANT4 and the subsequent loading of these meshes as assembly volumes; loading nested tessellated solids and tetrahedral meshes is also examined. As the technique makes the geometry suitable for automatic optimisation using smartvoxels, navigation through a simple tessellated volume has been found to be more than two orders of magnitude faster than that through the equivalent tessellated solid. Speed increases of more than two orders of magnitude were also observed for a more complex tessellated solid with voids and concavities. The technique was benchmarked for geometry load time, simulation run time and memory usage. Source code enabling the described functionality in GEANT4 has been made freely available on the Internet.

A CAD interface for GEANT4

Often CAD models already exist for parts of a geometry being simulated using GEANT4. Direct import of these CAD models into GEANT4 however,may not be possible and complex components may be diffcult to define via other means. Solutions that allow for users to work around the limited support in the GEANT4 toolkit for loading predefined CAD geometries have been presented by others, however these solutions require intermediate file format conversion using commercial software. Here within we describe a technique that allows for CAD models to be directly loaded as geometry without the need for commercial software and intermediate file format conversion. Robustness of the interface was tested using a set of CAD models of various complexity; for the models used in testing, no import errors were reported and all geometry was found to be navigable by GEANT4. Funding source: Cancer Australia (Department of Health and Ageing) Research Grant 614217