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Background: Due to its specific physical characteristics, proton irradiation is especially suited for irradiation of chordomas and chondrosarcoma in the axial skeleton. Robust plan optimization renders the proton beam therapy more predictable upon individual setup errors. Reported experience with the planning and delivery of robustly optimized plans in chordoma and chondrosarcoma of the mobile spine and sacrum, is limited. In this study, we report on the clinical use of robustly optimized, intensity modulated proton beam therapy in these patients.Methods: We retrospectively reviewed patient, treatment and acute toxicity data of all patients with chordoma and chondrosarcoma of the mobile spine and sacrum, treated between 1 April 2019 and 1 April 2020 at our institute. Anatomy changes during treatment were evaluated by weekly cone-beam CTs (CBCT), supplemented by scheduled control-CTs or ad-hoc control-CTs. Acute toxicity was scored weekly during treatment and at 3 months after therapy according to CTCAE 4.0.Results: 17 chordoma and 3 chondrosarcoma patients were included. Coverage of the high dose clinical target volume was 99.8% (range 56.1-100%) in the nominal and 80.9% (range 14.3-99.6%) in the voxel-wise minimum dose distribution. Treatment plan adaptation was needed in 5 out of 22 (22.7%) plans. Reasons for plan adaptation were either reduced tumor coverage or increased dose to the OAR.Conclusions: Robustly optimized intensity modulated proton beam therapy for chordoma and chondrosarcoma of the mobile spine is feasible. Plan adaptations due to anatomical changes were required in approximately 23 percent of treatment courses. (C) 2021 The Authors. Published by Elsevier B.V.

Purpose: Rotations of the prostate gland induce considerable geometric uncertainties in prostate cancer radiation therapy. Collimator and gantry angle adjustments can correct these rotations in intensity modulated radiation therapy. Modern volumetric modulated arc therapy (VMAT) treatments, however, include a wide range of beam orientations that differ in modulation, and corrections require dynamic collimator rotations. The aim of this study was to implement a rotation correction strategy for VMAT dose delivery and validate it for left-right prostate rotations. Methods and Materials: Clinical VMAT treatment plans of 5 prostate cancer patients were used. Simulated left-right prostate rotations between +15 degrees and -15 degrees were corrected by collimator rotations. We compared corrected and uncorrected plans by dose volume histograms, minimum dose (D-min) to the prostate, bladder surface receiving >= 78 Gy (S78) and rectum equivalent uniform dose (EUD; n=0.13). Each corrected plan was delivered to a phantom, and its deliverability was evaluated by gamma-evaluation between planned and delivered dose, which was reconstructed from portal images acquired during delivery. Results: On average, clinical target volume minimum dose (D-min) decreased up to 10% without corrections. Negative left-right rotations were corrected almost perfectly, whereas Dmin remained within 4% for positive rotations. Bladder S78 and rectum EUD of the corrected plans matched those of the original plans. The average pass rate for the corrected plans delivered to the phantom was 98.9% at 3% per 3 mm gamma criteria. The measured dose in the planning target volume approximated the original dose, rotated around the simulated left-right angle, well. Conclusions: It is feasible to dynamically adjust the collimator angle during VMAT treatment delivery to correct for prostate rotations. This technique can safely correct for left-right prostate rotations up to 15 degrees. (C) 2015 Elsevier Inc. All rights reserved

Purpose The purpose of this study was to investigate if FDG-PET and DWI identify the same or different targets for dose escalation in the GTV of HN cancer patients. Additionally, the dose coverage of DWI-targets in an FDG-PET-based dose painting plan was analyzed. Materials and methods Eighteen HN cancer patients underwent FDG-PET and DWI exams, which were converted to standardized uptake value (SUV)- and apparent diffusion coefficient (ADC)-maps. The correspondence between the two imaging modalities was determined on a voxel-level using Spearman's correlation coefficient ( ρ ). Dose painting plans were optimized based on the 50% isocontour of the maximum SUV ( SUV 50%max ). Dose coverage was analyzed in three different SUV- and three different ADC-targets using the mean dose and the near-minimum and near-maximum doses. Results The average maximum SUV was 13.9 and the mean ADC was 1.17·10 −3 mm 2 /s. The average ρ between SUV and ADC was −0.2 (range: −0.6 to 0.4). The ADC-targets were only partly overlapping the SUV 50%max -target and the dose parameters were significantly smaller in the ADC-targets compared to the SUV 50%max -target. Conclusions FDG-PET and DWI contain different information, resulting in different targets. Further information about failure patterns and dose relations can be obtained by adding DWI to currently ongoing dose painting trials.

We demonstrate direct frequency-comb (FC) spectroscopy of the dipole-forbidden 4s(2)S(1/2)-3d(2)D(5/2) transition in trapped (40)Ca(+) ions using an unamplified FC laser. The excitation is detected with nearly 100% efficiency using a shelving scheme in combination with single-ion imaging. The method demonstrated here has the potential to reach hertz-level accuracy, if a hertz-level linewidth FC is used in combination with confinement in the Lamb-Dicke regime.

Direct frequency comb spectroscopy is demonstrated for ions in a Paul trap for the first time. We measured a single-photon transition at 394 nm in a crystal of calcium ions with 0.5 MHz accuracy.

Two distinct high-accuracy laboratory spectroscopic investigations of the ${\mathrm{H}}_{2}$ molecule are reported. Anchor lines in the $EF^{1}\ensuremath{\Sigma}_{g}^{+}\ensuremath{-}X^{1}\ensuremath{\Sigma}_{g}^{+}$ system are calibrated by two-photon deep-UV Doppler-free spectroscopy, while independent Fourier-transform spectroscopic measurements are performed that yield accurate spacings in the $B^{1}\ensuremath{\Sigma}_{u}^{+}\ensuremath{-}EF^{1}\ensuremath{\Sigma}_{g}^{+}$ and $I^{1}\ensuremath{\Pi}_{g}\ensuremath{-}C^{1}\ensuremath{\Pi}_{u}$ systems. From combination differences accurate transition wavelengths for the $B\ensuremath{-}X$ Lyman and the $C\ensuremath{-}X$ Werner lines can be determined with accuracies better than $\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$, representing a major improvement over existing values. This metrology provides a practically exact database to extract a possible variation of the proton-to-electron mass ratio based on ${\mathrm{H}}_{2}$ lines in high-redshift objects. Moreover, it forms a rationale for equipping a future class of telescopes, carrying 30--40 m dishes, with novel spectrometers of higher resolving powers.

High accuracy frequency metrology on the 4s S-2(1/2)-4p P-2(1/2) transition in calcium ions is performed using laser cooled and crystallized ions in a linear Paul trap. Calibration is performed with a frequency comb laser, resulting in a transition frequency of f = 755 222 766.2 (1.7) MHz. The accuracy presents an improvement of more than one order of magnitude, and will facilitate a comparison with quasar data in a search for a possible change of the fine structure constant on a cosmological time scale.

We demonstrate phase stable, mJ-level parametric amplification of pulse pairs originating from a Ti:Sapphire frequency comb laser. The amplifier-induced phase shift between the pulses has been determined interferometrically with an accuracy of approximately 10 mrad. Typical phase shifts are on the order of 50-200 mrad, depending on the operating conditions. The measured phase-relation can be as stable as 20 mrad rms (1/300(th) of an optical cycle). This makes the system suitable for Ramsey spectroscopy at short wavelengths by employing harmonic upconversion of the double-pulses in nonlinear media.

An alternative technique for precision spectroscopy, that is rapidly gaining interest, is direct excitation of atomic transitions with a train of pulses from a frequency comb laser. As the high peak intensity of such ultrashort pulses allows efficient upconversion of an infrared frequency comb output to higher frequencies, it seems very promising for extending high-resolution spectroscopy to the VUV and XUV spectral region.

A multi-species linear Paul trap has been constructed. Ionic transitions of Ca ion are measured to a higher precision, enabling a more precise comparison. Spectroscopy on this line is done by direct excitation with a frequency-doubled home-built frequency comb oscillator.

Here we present a noncollinear optical parametric chirped pulse amplification (NOPCPA) system that produces 7.6 femtosecond pulses with a peak power exceeding 2 TW at a repetition rate of 30 Hz.

The phase stability of broadband (280 nm bandwidth) terawatt-class parametric amplification was measured, for the first time to our knowledge, with a combination of spatial and spectral interferometry. Measurements at four different wavelengths from 750 to 900 nm were performed in combination with numerical modeling. The phase stability is better than 1/23 rms of an optical cycle for all the measured wavelengths, depending on the phase-matching conditions in the amplifier. © 2007 Optical Society of America.

We demonstrate the generation of near-Fourier-limited 9.8 plusmn 0.3 fs laser pulses with an intensity exceeding a terawatt at 30 Hz repetition rate, using noncollinear optical parametric chirped pulse amplification. Amplified fluorescence is kept below 1%.

Experiments with various techniques that can facilitate prototyping are reported. It has been recognized that three of these used most extensively represent three distinct approaches to supporting the development of large prototype systems. All three are successful at controlling the impact of change, but they differ in how they achieve that control as well as in the ways and extents to which they support reuse and consistency management. The authors characterize the approaches, describe the tools developed for them and experiences with them. A comparative evaluation of the approaches is included. >

Session 5, entitled “People in Context”, addressed the question of how to understand the role of people in processes by looking at the vtarious contexts in which they operate. The discussion was organized by examining the process model context, the team context, the project context, and the organization context. Dewayne Perry organized the session by discussion of four different contexts in which to consider people: the process model context, the teani context, the project context, and the organization

Session 1, entitled ‘People, Processes and Practice ’, was divided into two discussion sections. The first included discussions of how people are treated and supported in process models in terms of control and guidance, issues of context switching, and aspects of informality. The second focused primarily on deviating from the defined processes, detecting and resolving those deviations, and tailoring processes

We have performed an accurate frequency calibration of the $4{s}^{2} {}^{1}{S}_{0}\ensuremath{\rightarrow}4s4p {}^{1}{P}_{1}$ principal resonance line of the neutral calcium atom at 423 nm. Doppler-free cw excitation on a Ca atomic beam was performed by utilizing a Sagnac geometry in the alignment of the excitation beams. From frequency calibrations against a frequency comb, stabilized to a global positioning system (GPS) disciplined Rb standard, the transition frequency is determined at 709 078 373.01(35) MHz for the main $^{40}\mathrm{Ca}$ isotope. Slightly lower accuracies are obtained for the transition frequencies of the less abundant isotopes. The achieved fractional uncertainty of $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ exceeds the requirements for including this transition in investigations that aim to probe a possible variation in the fine-structure constant $\ensuremath{\alpha}$ on cosmological time scales.

Publisher Summary This chapter discusses the angiogenesis in solid tissue and cell suspension grafts placed in the central nervous system (CNS) of adult mammalian hosts. It is confirmed that the graft and not the surrounding host tissue dictates the presence or absence of blood–brain and brain–blood barriers within the graft. To survive and thrive, grafted tissue must be supplied with an extensive network of blood vessels perfuse with host blood. The time course for development of this vascular network is equally important; cell viability is dependent upon oxygen, glucose, and additional energy yielding substrates and other nutrients conveyed to the tissue within the blood. The grafting of solid central nervous system (CNS) tissue or the tissue of peripheral origin into the brain/spinal cord of a host necessarily compromises the host's blood–brain and brain–blood barriers. The absence of a blood–brain barrier in the adrenal gland grafted intracerebrally may be relevant for the treatment of Parkinson's disease with blood–borne therapeutics. Compared to solid tissue grafts, cell suspension grafts have the potential of becoming vascularized rapidly.

Embryonic neural tissues were taken from the ventral mesencephalon, the striatal anlage, the cerebellum, or the dorsal telencephalon. Prior to grafting these tissues were dissociated. This provided the opportunity to generate experimental cografts and allowed the introduction of neuronal tracers. Projections from grafts that contained dopaminergic neurons of the mesencephalon were identified immunocytochemically with antisera to tyrosine hydroxylase. Acetylcholinesterase histochemistry was employed to both stain the graft and to visualize graft efferent fibers. Moreover, dissociated tissues, with the exception of the ventral mesencephalon, were treated in vitro with rhodamine-conjugated microspheres. The immature cells incorporated the tracer in vitro. Labeled grafts were placed adjacent to large fiber tracts of the recipient brain or into the lateral ventricle and grown for one to two months. Different types of neurons within the grafts retained the rhodamine tracer. Some of the labeled neurons were positive for acetylcholinesterase. Efferent fibers from the different neural grafts followed similar routes within the host brain. Fibers containing microspheres projected commonly along the nearest host pathway or the labeled fibers followed the reactive glia along the original stab wound. Grafts that were located within the lateral ventricle projected their efferent fibers adjacent to the ventricular surface. Similar routes were followed by efferent fibers from trasplanted dopaminergic neurons. One of the projection routes along the hosts corpus callosum was confirmed by horseradish peroxidase tracer transport. We conclude that elongation of graft pathways may occur along existing fiber tracts of the host brain, near structures of the ventricular surface, and alongside glia scars of a graft placement tract.

An optical parametric chirped pulse amplifier system for pulse pairs is presented. The differential phase stability of the pulse pairs is 20 mrad, giving good prospects for high resolution Ramsey spectroscopy in the extreme ultraviolet.

To add to the debate on a possible variation of the fine structure constant, we perform frequency comb spectroscopy on laser cooled (calcium) ions in a linear Paul trap.