Assessment of Photon-Counting Computed Tomography for Quantitative Imaging in Radiation Therapy.

Purpose: To test a first-generation clinical photon-counting computed tomography (PCCT) scanner's capabilities to characterize materials in an anthropomorphic head phantom for radiation therapy purposes.

Methods And Materials: A CIRS 731-HN head-and-neck phantom (CIRS/SunNuclear) was scanned on a NAEOTOM Alpha PCCT and a SOMATOM Definition AS+ with single-energy and dual-energy CT techniques (SECT and DECT, respectively), both scanners manufactured by Siemens (Siemens Healthineers). A method was developed to derive relative electron density (RED) and effective atomic number (EAN) from linear attenuation coefficients (LACs) of virtual mono-energetic images and applied for the PCCT and DECT data.

Clinical practice in European centres treating paediatric posterior fossa tumours with pencil beam scanning proton therapy.

Background And Purpose: As no guidelines for pencil beam scanning (PBS) proton therapy (PT) of paediatric posterior fossa (PF) tumours exist to date, this study investigated planning techniques across European PT centres, with special considerations for brainstem and spinal cord sparing.

Materials And Methods: A survey and a treatment planning comparison were initiated across nineteen European PBS-PT centres treating paediatric patients. The survey assessed all aspects of the treatment chain, including but not limited to delineations, dose constraints and treatment planning.

Effects of enrichment strategies on outcome of adrecizumab treatment in septic shock: analyses of the phase II adrenomedullin and outcome in septic shock 2 trial.

Purpose: Adrecizumab, a non-neutralizing antibody of adrenomedullin (ADM) was recently investigated regarding its potential to restore endothelial barrier function in septic shock patients with high plasma ADM levels. Circulating dipeptidyl peptidase 3 (cDPP3), a protease involved in the degradation of several cardiovascular mediators, represents another biological pathway strongly associated with outcome in septic shock, although unrelated to ADM. Therefore, the prognosis of patients with elevated cDPP3 may not be influenced by Adrecizumab.

Stopping-power ratio estimation for proton radiotherapy using dual-energy computed tomography and prior-image constrained denoising.

Background: Dual-energy computed tomography (DECT) is a promising technique for estimating stopping-power ratio (SPR) for proton therapy planning. It is known, however, that deriving electron density (ED) and effective atomic number (EAN) from DECT data can cause noise amplification in the resulting SPR images. This can negate the benefits of DECT.

Comparison of CT-number parameterization models for stoichiometric CT calibration in proton therapy.

Purpose: This study compares the predictions of three parameterization models used in previously published works, implementing the stoichiometric CT calibration for proton therapy, and a further two alternative parameterizations suggested here.

Methods: Stoichiometric calibrations of patient CT-number to stopping-power ratio (SPR) were performed for four CT protocols using tissue substitutes supplied by CIRS (CIRS Inc., Norfolk, VA, USA).

Technical Note: On the calculation of stopping-power ratio for stoichiometric calibration in proton therapy.

Purpose: The quantitative effects of assumptions made in the calculation of stopping-power ratios (SPRs) are investigated, for stoichiometric CT calibration in proton therapy. The assumptions investigated include the use of the Bethe formula without correction terms, Bragg additivity, the choice of I-value for water, and the data source for elemental I-values.

Methods: The predictions of the Bethe formula for SPR (no correction terms) were validated against more sophisticated calculations using the SRIM software package for 72 human tissues.

Real-time dynamic MLC tracking for inversely optimized arc radiotherapy.

Background And Purpose: Motion compensation with MLC tracking was tested for inversely optimized arc radiotherapy with special attention to the impact of the size of the target displacements and the angle of the leaf trajectory.

Materials And Methods: An MLC-tracking algorithm was used to adjust the MLC positions according to the target movements using information from an optical real-time positioning management system. Two plans with collimator angles of 45 degrees and 90 degrees , respectively, were delivered and measured using the Delta(4)(R) dosimetric device moving in the superior-inferior direction with peak-to-peak displacements of 5, 10, 15, 20 and 25 mm and a cycle time of 6s.

DMLC motion tracking of moving targets for intensity modulated arc therapy treatment: a feasibility study.

Purpose: Intensity modulated arc therapy offers great advantages with the capability of delivering a fast and highly conformal treatment. However, moving targets represent a major challenge. By monitoring a moving target it is possible to make the beam follow the motion, shaped by a Dynamic MLC (DMLC).