It is shown that the continuum level density (CLD) at unbound energies can be
calculated with the complex scaling method (CSM), in which the energy spectra
of bound states, resonances and continuum states are obtained in terms of $L^2$
basis functions. In this method, the extended completeness relation is applied
to the calculation of the Green functions, and the continuum-state part is
approximately expressed in terms of discretized complex scaled continuum
solutions. The obtained result is compared with the CLD calculated exactly from
the scattering phase shift. The discretization in the CSM is shown to give a
very good description of continuum states. We discuss how the scattering phase
shifts can inversely be calculated from the discretized CLD using a basis
function technique in the CSM.Comment: 14 pages, 9 figures, To be published in Progress of Theoretical
Physic
BackgroundWe performed a dosimetric comparison of spot-scanning proton therapy (SSPT) and intensity-modulated radiation therapy (IMRT) for hepatocellular carcinoma (HCC) to investigate the impact of tumor size on the risk of radiation induced liver disease (RILD).MethodsA number of alternative plans were generated for 10 patients with HCC. The gross tumor volumes (GTV) varied from 20.1 to 2194.5 cm3. Assuming all GTVs were spherical, the nominal diameter was calculated and ranged from 3.4 to 16.1 cm. The prescription dose was 60 Gy for IMRT or 60 cobalt Gy-equivalents for SSPT with 95% planning target volume (PTV) coverage. Using IMRT and SSPT techniques, extensive comparative planning was conducted. All plans were evaluated by the risk of RILD estimated using the Lyman-normal-tissue complication probability model.ResultsFor IMRT the risk of RILD increased drastically between 6.3–7.8 cm nominal diameter of GTV. When the nominal diameter of GTV was more than 6.3 cm, the average risk of RILD was 94.5% for IMRT and 6.2% for SSPT.ConclusionsRegarding the risk of RILD, HCC can be more safely treated with SSPT, especially if its nominal diameter is more than 6.3 cm.
The results suggested that by properly adjusting irradiation control parameters, gated proton spot-scanning beam therapy can be robust to target motion. This is an important first step toward establishing treatment plans in real patient geometry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.