Total Body Irradiation (TBI) patients are often
treated at extended distances of several meters, with blocking made from high-Z
materials placed close to the patients’ skin. Evaluating the dose under a block (e.g., for implantedmedical device
shielding purposes) in such a geometry is challenging. We compare the performance of two commonly used dose
calculation algorithms, Anisotropic Analytical
Algorithm (AAA) and Acuros XB, with Optically StimulatedLumine- scence (OSLD) and ion chamber measurements in
phantoms. The calculations and phantom measurements are also compared with in-vivo OSLD measure- ments. We find that OSLD and ion chamber
measurements in phantom are good predictors of in-vivo measurements, while both AAA and
Acuros XB sys- tematically overestimate the block transmission. We found Acuros XB to be
accurate enough for a rough upper estimate (dose under block overestimated by 7%-22%), while for AAA the overestimate was more severe (90%-110%); the reason is that AAA does not account for the increase in
pair production
References
[1]
Van Dyk, J., Galvin, J.M., Glasgow, G.P., et al. (1986) The Physical Aspects of Total and Half Body Photon Irradiation. AAPM Report No. 17, American Association of Physicists in Medicine.
[2]
Wong, J., Filippi, A.R., Dabaja, S., Yahalom, J. and Specht, L. (2018) Total Body Irra-diation: Guidelines from the International Lymphoma Radiation Oncology Group (ILROG). International Journal of Radiation Oncology · Biology · Physics, 101, 521-529. https://doi.org/10.1016/j.ijrobp.2018.04.071
[3]
Shank, B. (1983) Techniques of Magna-Field Irradiation. International Journal of Radiation Oncology · Biology · Physics, 9, 1925-1931. https://doi.org/10.1016/0360-3016(83)90364-4
[4]
Varian Medical Systems (2021) Eclipse Photon and Electron Algorithms Reference Guide. Varian Medical Systems, Palo Alto, CA, USA. https://www.myvarian.com/
[5]
Miften, M., Mihailidis, D., Kry, S.F., et al. (2019) Management of Radiotherapy Patients with Implanted Cardiac Pacemakers and Defibrillators: A Report of the AAPM TG-203. Medical Physics, 46, e757-e788. https://doi.org/10.1002/mp.13838
[6]
Spirydovich, S., Papiez, L., Langer, M., Sandison, G. and Thai, V. (2006) High Density Dental Materials and Radiotherapy Planning: Comparison of the Dose Predictions Using Superposition Algorithm and Fluence Map Monte Carlo Method with Radio-chromic Film Measurements. Radiotherapy & Oncology, 81, 309-314. https://doi.org/10.1016/j.radonc.2006.10.010
[7]
Lamichhane, N. and Studenski, T. (2020) Improving TBI Lung Dose Calculations: Can the Treatment Planning System Help? Medical Dosimetry, 45, 168-171. https://doi.org/10.1016/j.meddos.2019.09.004
[8]
Ulmer, W., Pyyry, J. and Kaissl, W. (2005) A 3D Photon Superposition/Convolution Algorithm and Its Foundation on Results of Monte Carlo Calculations. Physics in Medicine & Biology, 50, 1767-1790. https://doi.org/10.1088/0031-9155/50/8/010
[9]
Tiilikainen, L., Helminen, H., Torsti, T., et al. (2008) A 3D Pencil-Beam-Based Super-position Algorithm for Photon Dose Calculation in Heterogeneous Media. Physics in Medicine & Biology, 53, 3821-3839. https://doi.org/10.1088/0031-9155/53/14/008
[10]
Vasilliev, O.N., Wareing, J., Damis, A.M., et al. (2008) Feasibility of a Multigroup Deterministic Solution Method for Three-Dimensional Radiotherapy Dose Calculations. International Journal of Radiation Oncology · Biology · Physics, 72, 220-227. https://doi.org/10.1016/j.ijrobp.2008.04.057
[11]
Han, T., Mikell, J.K., Salehpour, M. and Mourtada, F. (2011) Dosimetric Comparison of Acuros XB Deterministic Radiation Transport Method with Monte Carlo and Model-Based Convolutional Methods in Heterogeneous Media. Medical Physics, 38, 2651-2664. https://doi.org/10.1118/1.3582690
[12]
Johns, H.E. and Cunningham, J.R. (1983) The Physics of Radiology. 4 Edition, Charles C Thomas, Springfield.
