Improving interinstitutional and intertechnology consistency of pulmonary SBRT by dose prescription to the mean internal target volume dose.

Purpose: Dose, fractionation, normalization and the dose profile inside the target volume vary substantially in pulmonary stereotactic body radiotherapy (SBRT) between different institutions and SBRT technologies. Published planning studies have shown large variations of the mean dose in planning target volume (PTV) and gross tumor volume (GTV) or internal target volume (ITV) when dose prescription is performed to the PTV covering isodose. This planning study investigated whether dose prescription to the mean dose of the ITV improves consistency in pulmonary SBRT dose distributions.

The impact of dose escalation on secondary cancer risk after radiotherapy of prostate cancer.

Purpose: To estimate secondary cancer risk due to dose escalation in patients treated for prostatic carcinoma with three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated RT (IMRT), and spot-scanned proton RT.

Methods And Materials: The organ equivalent dose (OED) concept with a linear-exponential, a plateau, and a linear dose-response curve was applied to dose distributions of 23 patients who received RT of prostate cancer. Conformal RT was used in 7 patients, 8 patients received IMRT with 6- and 15-MV photons, and 8 patients were treated with spot-scanned protons.

Evaluation of a commercial electron treatment planning system based on Monte Carlo techniques (eMC).

A commercial electron beam treatment planning system on the basis of a Monte Carlo algorithm (Varian Eclipse, eMC V7.2.35) was evaluated.

The impact of IMRT and proton radiotherapy on secondary cancer incidence.

Background And Purpose: There is concern about the increase of radiation-induced malignancies with the application of modern radiation treatment techniques such as intensity-modulated radiotherapy (IMRT) and proton radiotherapy. Therefore, X-ray scatter and neutron radiation as well as the impact of the primary dose distribution on secondary cancer incidence are analyzed.

Material And Methods: The organ equivalent dose (OED) concept with a linear-exponential and a plateau dose-response curve was applied to dose distributions of 30 patients who received radiation therapy of prostate cancer.

Patient specific optimization of the relation between CT-hounsfield units and proton stopping power with proton radiography.

The purpose of this work is to show the feasibility of using in vivo proton radiography of a radiotherapy patient for the patient individual optimization of the calibration from CT-Hounsfield units to relative proton stopping power. Water equivalent tissue (WET) calibrated proton radiographs of a dog patient treated for a nasal tumor were used as baseline in comparison with integrated proton stopping power through the calibrated CT of the dog. In an optimization procedure starting with a stoichiometric calibration curve, the calibration was modified randomly.

First proton radiography of an animal patient.

The purpose of this work is to show the feasibility of proton radiography in terms of radiation dose, imaging speed, image quality (density and spatial resolution), and image content under clinical conditions. Protons with 214 MeV energy can penetrate through most patients and were used for imaging. The measured residual range (or energy) of the protons behind the patient was subtracted from the range without an object in the beam path and used to create a projected image.

The water equivalence of solid materials used for dosimetry with small proton beams.

Various solid materials are used instead of water for absolute dosimetry with small proton beams. This may result in a dose measurement different to that in water, even when the range of protons in the phantom material is considered correctly. This dose difference is caused by the diverse cross sections for inelastic nuclear scattering in water and in the phantom materials respectively.

CT based lung density correction verification with in vivo dosimetry using diodes.

In vivo dose measurements with diodes are easy to perform. The first aim of our study was to show whether diode measurements of the patient exit doses are precise enough for verifying inhomogeneity corrections used for treatment planning. The second aim was to assess the precision of the modified Batho Law inhomogeneity correction of the CadPlan treatment planning system.

Influence of respiration-induced organ motion on dose distributions in treatments using enhanced dynamic wedges.

The mean velocity of respiration-induced organ motion in cranio-caudal direction is of the same magnitude as the velocity of the moving jaw during a treatment with an enhanced dynamic wedge. Therefore, if organ motion is present during collimator movement, the resulting dose distribution in wedge direction may differ from that obtained for the static case, i.e.

[Evaluation of the electron density phantom CIRS Model 62].

The properties of the electron density phantom CIRS M62 were studied. Physical and electron densities were calculated for all tissue substitutes, and compared to the values given in the data sheet and to the recommendations of the ICRU Report 44. The phantom was scanned in standard-CT and spiral-CT mode with different acquisition parameters.

On small angle multiple coulomb scattering of protons in the gaussian approximation.

Experimental data from the literature on small-angle multiple Coulomb scattering of protons in various materials were analysed in order to device an equation for the scattering angle in the Gaussian approximation. In comparison to Highland's well-known formula, the present approximation can be integrated to take into account energy loss in the scattering media. In addition, it is more precise than Highland's formulation for thin and thick scatterers consisting of elements with low atomic number.