Influence Of Profile Research Articles

Proton deflectometry analysis in magnetized plasmas: Magnetic field reconstruction in one dimension.

Proton deflectometry is used in magnetized high-energy-density plasmas to observe electromagnetic fields. We describe a reconstruction algorithm to recover the electromagnetic fields from proton fluence data in 1-D. The algorithm is verified against analytic solutions and applied to example data. Next, we study the role of source fluence uncertainty for 1-D reconstructions. We show that reconstruction boundary conditions can be used to constrain the source fluence profile and use this to develop a reconstruction using a specified pair of boundary conditions on the magnetic field. From these considerations, we experimentally demonstrate a hybrid mesh-fluence reconstruction technique where fields are reconstructed from fluence data in an interior region with boundary conditions supplied by direct mesh measurements at the boundary.

Fluence profiling at JSI TRIGA reactor irradiation facility

We present an analysis of the fluence profile at the JSI TRIGA neutron reactor facility in Ljubljana. For the study, multi-pad Low-Gain Avalanche Diodes (LGADs) are used. The deactivation of acceptor doping in the gain layer implant due to the irradiation, typical of LGAD devices, is exploited to map the fluence profile inside the irradiation channels. The amount of active doping of the LGAD gain layer is extracted via capacitance–voltage measurements for each pad before and after irradiation to a fluence of 1.5 × 1015neq/cm2, where neq stands for 1 MeV equivalent neutron count, providing a precise and prompt measurement of the fluence distribution over the LGAD sensor. Experimental results are compared to neutron fluence expectations calculated with Monte Carlo techniques.

Analysis of Factors Associated with Increased Hematology/Oncology Fellowship Twitter Account Followership

Background:Twitter has proven to be a powerful tool in medical education by providing a conduit for disseminating research, educating medical trainees, and facilitating discourse between physicians. With training programs transitioning to virtual interviews since the COVID-19 pandemic, programs' social media accounts have also become useful for interaction between applicants and programs and have been shown to influence applicant perceptions of programs (Kapsetaki et al., Interact J Med Res 2023; Schweitzer et al., J AM Osteopath Assoc. 2012). Given Twitter's importance and potential for hematology/oncology fellowship programs, we aimed to analyze its utilization among programs and characterize what attributes increase follower count, an important marker of a profile's influence (Bakshy et al., Association for Computing Machinery 2011). Methods: All data was collected between July 1st and July 19th, 2023. We identified adult hematology/oncology fellowship programs in the United States using the Electronic Residency Application Service and searched for Twitter profiles for each program. We then analyzed each profile for number of educational, departmental, academic, and social posts. Program demographics, including program size and community or academic status, were obtained from FREIDA. NCI, NCCN, and US News Ranking status were obtained from the respective websites. Analysis included Spearman correlation, ANOVA, and Chi-Square testing. Results: Of the 180 hematology/oncology fellowship programs identified, 44 (24%) had Twitter accounts. Of these programs, 27 (61.4%) were university-based, 2 (4.5%) were community-based, 1 (2.3%) was community/university based, while 14 (31.8%) were categorized as “other”. NCCN status (p<0.05) was associated with larger Twitter following. Of the Twitter accounts, 39 (88.6%) were deemed to be active, defined as having tweeted since July 1 st, 2022. More Twitter posts (R 2 = 0.49, p<0.001) was associated with higher number of total followers. Amongst post type, more departmental (R 2 = 0.41, p<0.001), academic (R 2 = 0.46, p<0.001), and “Other” (R 2 = 0.35, p<0.001) posts not meeting criteria of the other subsets, were correlated with increased Twitter followers. Increased number of profiles followed by the fellowship program's account (R 2 = 0.2, p<0.05) and increased social posts (R 2 = 0.1, p<0.05) had weak positive associations with Twitter following. Number of fellows per program did not have an association with number of Twitter followers. Conclusions: In our study, NCCN status and larger tweet volume, specifically about academic and departmental topics, were more strongly associated with increased Twitter following. Higher tweet number offers more opportunity for retweets and commenting from followers, thereby increasing visibility. From a follower's perspective, more frequent posting likely increases the value of the Twitter page as one that is truly providing real time program updates. Highlighting academic accomplishments and achievements of the department's faculty and house staff could be attracting applicants and medical professionals by offering insight into the quality of academic output, staff, and training at the program. Programs with NCCN status could be drawing followers through associated prestige but also tend to be larger programs that are more likely to have the resources to update and develop accounts. A similar study conducted in pulmonary/critical care fellowships (Gandotra et al., ATS 2021) also showed higher follower count with larger post volume. They noted that social and clinical tweets attracted more followers, but the study utilized differing post classification definitions from our study. An investigation in psychiatry residencies using the same definitions for classifying posts, but instead evaluating Instagram (Bernstein et al., Academic Psychiatry 2021) yielded similar results to ours. Our data also shows that most hematology/oncology fellowships do not have Twitter profiles. With the growing importance of social media, this offers a clear opportunity for furthering engagement with the medical community and potential fellows. Posting regularly, and about academic and departmental topics, could help maximize the Twitter profile's influence, while also providing fellowship applicants with useful information in the virtual era.

Photoacoustic spectrum analysis for spherical target size and optical property determination: A feasibility study

The photoacoustic signal generated by an optically absorbing target is determined by the spatial profile of absorbed optical energy within the target. The analysis of the time profile and frequency content of the signal enables the recovery of the geometry of the object, as well as information about the optical properties. The photoacoustic response of spheres with a homogeneous absorbed optical energy profile is well described, and it is known that the width of the photoacoustic pulse is determined by the diameter of the sphere and its sound speed. In practice, the optical attenuation coefficients within the sphere will result in an inwardly decaying fluence profile leading to a similarly decaying absorbed optical energy profile. Further, the optical attenuation coefficients may be inhomogeneously distributed in the sphere. The implication for both cases is that the existing model for spheres does not fully apply. In this work, we developed analytical expressions for the photoacoustic time traces and amplitude spectra generated by a sphere with absorbed optical energy only in a spherical shell, and by a sphere with an inwardly decaying optical energy profile. Numerical simulations and experiments were conducted on these two imperfect sphere types. Fitting our model to the simulated or measured spectra allowed us to test our model’s ability to extract the sphere size and optical properties. We found that the radii can be recovered with high accuracy, even when the frequency response of the detector recording the photoacoustic pulse is not precisely known. The model was found to be less sensitive in recovering the optical attenuation coefficient, but it is feasible when the detector’s frequency response is well known.

COMBINED METHOD OF BULK MATERIAL SHIELDING EVALUATION FOR 200 MEV HIGH ENERGY NEUTRON SOURCE USING PHITS MODELLING AND PARTIAL DENSITY

Neutron encounters difficulties in shielding protection. Thus, many researchers have performed simulation and experimental research on neutron shielding materials. The characteristic of materials is highly dependent on neutron energy. The evaluation of neutron shielding for various materials, such as iron, concrete, aluminum, and borated polyethylene (BPE), was conducted in this paper through simulation using a Monte Carlo code of PHITS 3.27 and calculation via partial density method. A mono-energetic neutron source with an energy of 200 MeV is emitted perpendicular to the shielding material with a thickness of 105 cm. The parameters measured in this analysis include flux, fast neutron removal cross-section, neutron depth dose, ambient dose H*(10) equivalent, and neutron dose reduction factor (RF). Results show that iron is a good material against high-energy neutron and secondary photon radiation at the energy range with the highest removal cross-section and the lowest RF value (0.39), followed by concrete, BPE, and aluminum. The integrated fluence and effective dose profiles were consistent with previous results in the literature. Benchmarking calculation of neutron dose RF was conducted with other publications and was in good agreement within the value range.

GEANT4 dose estimations of solar protons: Al and PMMA-Bi2O3 shielding for space exploration

Adverse effects of long-term exposure to galactic cosmic radiation (GCR) pose a clear obstacle to future space exploration programs. In addition to GCR we have solar particle radiation. We simulated the latter using a scaled fluence profile of solar protons taken from a literature study that comprises about three solar cycles. The model is a three-layer stack that includes shielding material and muscular tissue. Our simulation strategy uses protons as precursor radiation of neutrons. Subsequently, the shield is adjusted for thickness, dictated by an average depth at which neutrons are created through various processes during the simulation. Neutrons are then energy-binned and a corresponding neutron flux is simulated. Particles generated during the second phase of the simulation, i.e. by neutrons, are then counted toward absorbed dose within the muscular tissue layer. Clearly, the dynamics of the process is not captured by the simulation, nevertheless an overview of neutron yield can be estimated and the absorbed dose. The objective is to provide some insight about the effect of the new composite shield, PMMA-Bi2O3, that has an intrinsic capability for gamma dose reduction, compared to a more traditional aluminum shield.

Femtosecond Bessel beam induced ladder-like LIPSS on trimetallic surface for SERS-based sensing of Tetryl and PETN

Laser-induced periodic surface structures (LIPSS) have emerged as a potential branch of nanophotonics, offering unparalleled applications in numerous other research fields such as on-chip microelectronics, hydrogen evolution, solar-energy conversion, photodetectors, photocatalysis, and sensing. In this study, for the first time, we have created novel, Ag-Au-Cu alloyed trimetallic, ladder-like LIPSS nanostructures engaging an axicon-generated femtosecond Bessel beam. The LIPSS formation mechanism through modulation of ablation fluence profile, involving interference of photon-induced surface plasmon polariton with incident beam, has been meticulously divulged. The overlapping feature of Bessel beam profiles has been considered to improve the coupling of electromagnetic modes with the pre-patterned surfaces. The period (Λ) of the fabricated low spatial frequency LIPSS has been estimated to be 540 ± 12 nm. Also, as a comparative study, the distinct topographical features of nanostructures generated under a Gaussian beam with an identical fluence has also been presented. Additionally, these trimetallic plasmonic nanostructures have demonstrated outstanding excellence as active surface-enhanced Raman scattering substrates for sensing applications. Traces (200 nM) of real-time explosives such as Tetryl and pentaerythritol tetranitrate (PETN) have been detected, while achieving enhancement factors in the range of 105, making these viable for practical applications.

Photon count rates estimated from 1980 clinical CT scans.

All photon counting detectors have a characteristic count rate over which their performance degrades. Degradation in the clinical setting takes the form of increased noise, reduced material quantification accuracy, and image artifacts. Count rate is a function of patient attenuation, beam filtration, scanner geometry, and X-ray technique. To guide protocol and technology development in the photon counting space, knowledge of clinical count rates spanning the complete range of clinical indications and patient sizes is needed. In this paper, we use clinical data to characterize the range of computed tomography (CT) count rates. We retrospectively gathered 1980 patient exams spanning the entire body (head/neck/chest/abdomen/extremity) and sampled 36951 axial image slices. We assigned the tissue labels air/lung/fat/soft tissue/bone to each voxel for each slice using CT number thresholds. We then modeled four different bowtie filters, 70/80/100/120/140kV spectra, and a range of mA values. We forward-projected each slice to obtain detector-incident count rates, using the geometry of a GE Revolution Apex scanner. Our analysis divided the detector into thirds: the central one-third, one-third of the detector split into two equal regions adjacent to the central third, and the final one-third divided equally between the outer detector edges. We report the 99th percentile of counts to mimic the upper limits of count rates making passing through a patient as a function of patient water equivalent diameter. We also report the percentage of patient scans, by body region, over different count rate thresholds for all combinations of bowtie and beam energy. For routine exam types, we recorded count rates of approximately 3.5×108 counts/mm2 /s in the torso, extremities, and brain. For neck scans, we observed count rates near 6×108 counts/mm2 /s. Our simulations of 1000mA, appropriately mimicking the mA needs for fast pediatric, fast thoracic, and cardiac scanning, resulted in count rates of over 10×108 counts/mm2 /s for the torso, extremities, and brain. At 1000mA, for the neck region, we observed count rates close to 2×109 counts/mm2 /s. Importantly, we saw only a small change in maximum count rate needs over patient size, which we attribute to patient mis-positioning with respect to the bowtie filters. As expected, combinations of kV and bowtie filter with higher beam energies and wider/less attenuating bowtie fluence profiles lead to higher count rates relative to lower energies. The 99th-50th percentile count rate changed the most for the torso region, with a maximum variation of 3.9×108 to 1.2×107 counts/mm2 /s. The head/neck/extremity regions had less than a 50% change in count rate from the 99th to 50th percentiles. Our results are the first to use a large patient cohort spanning all body regions to characterize count rates in CT. Our results should be useful in helping researchers understand count rates as a function of body region and mA for various combinations of bowtie filter designs and beam energies. Our results indicate clinical rates >1×109 counts/mm2 /s, but they do not predict the image quality impact of using a detector with lower characteristic count rates.

The generation and control of serpentine femtosecond laser filament array

Some potential applications require controllable curved femtosecond laser filaments. We show how a gas lattice medium with periodic refractive index profiles can generate a serpentine filament array of a femtosecond laser Gaussian pulse. The simulation findings show that the curved characteristics (bending times and degree), spatial evolution (onset, termination and interval) and energy fluence profiles of the filaments, can be flexibly controlled by adjusting the various parameters of the gas lattice. When collapsing Gaussian laser pulse is coupled into the asymmetric gas lattice, the optical waveguide effect in a medium with a refractive index gradient plays a vital role in forming the continuously curved trajectory. By adjusting the gas lattice parameters, serpentine filaments with customised characteristics can also be obtained. Our research provides a new method for manipulating the strong nonlinear propagation trajectories, which is for the first time to tailor serpentine filaments by utilising a modulated dielectric medium and offers a unique solution for many potential applications.

Optimal Delivery of Fluence Profile Using Dynamic Multi-Leaf Collimator Leaf Trajectory Optimization

In this paper we show how to employ dynamically generated fluence maps to generate the perfect balance between distribution time and fluence map quality. Our technique is based on a mathematical model that optimizes leaf trajectories and dosage rates for a specific delivery time in order to accurately mimic the desired fluence pattern. We will apply the typical two-step design method to handle the problem of fluence map distribution. The optimization problem is tackled by first optimizing for fluence mapping and then using the leaf-sequencing method to generate precise fluence maps. We formulate dosage rate and leaf trajectory optimization as a non-convex constant optimization problem and use an interior point technique to find the best solution based on arbitrarily adjusted acceptable beginning results. With a prostate example, we put our method to the test and display the resulting balance curves.

Model-based machine learning for the recovery of lateral dose profiles of small photon fields in magnetic field

Objective. To investigate the feasibility to train artificial neural networks (NN) to recover lateral dose profiles from detector measurements in a magnetic field. Approach. A novel framework based on a mathematical convolution model has been proposed to generate measurement-less training dataset. 2D dose deposition kernels and detector lateral fluence response functions of two air-filled ionization chambers and two diode-type detectors have been simulated without magnetic field and for magnetic field B = 0.35 and 1.5 T. Using these convolution kernels, training dataset consisting pairs of dose profiles and signal profiles were computed for a total of 108 2D photon fluence profiles (80% training/20% validation). The NN were tested using three independent datasets, where the second test dataset has been obtained from simulations using realistic phase space files of clinical linear accelerator and the third test dataset was measured at a conventional linac equipped with electromagnets. Main results. The convolution kernels show magnetic field dependence due to the influence of the Lorentz force on the electron transport in the water phantom and detectors. The NN show good performance during training and validation with mean square error reaching a value of 1e-6 or smaller. The corresponding correlation coefficients R reached the value of 1 for all models indicating an excellent agreement between expected and predicted The comparisons between and using the three test datasets resulted in gamma indices (1 mm/1% global) <1 for all evaluated data points. Significance. Two verification approaches have been proposed to warrant the mathematical consistencies of the NN outputs. Besides offering a correction strategy not existed so far for relative dosimetry in a magnetic field, this work could help to raise awareness and to improve understanding on the distortion of detector’s signal profiles by a magnetic field.

Lissajous curve oscillations in laser welding

In this study, a new approach for laser beam oscillations in welding is proposed. Commonly frequency is used as the principal process parameter when driving beam oscillation but often leads to a suboptimal fluence distribution. If velocity is modulated this presents significant opportunity for enhancing thermal distribution within welds. Controlling galvanometer velocity instead of the frequency will create ‘trajectory’ dependent fluence distribution opportunities. Here we investigate the use of Lissajous curves for this purpose since these allow rapid parametric design adaptation. Fluence profiles are obtained, analysed and presented. Using this method key melt pool characteristics can be modulated including temperature difference within weld, max temperature achieved and the cooling rate. To illustrate this, we present a series of remelted surfaces which show the effect of modulated fluence on weld morphology.

Long-range propagation of ultrafast ionizing laser pulses in a resonant nonlinear medium

We study the propagation of 0.05--1 TW power, ultrafast laser pulses in a 10-m-long rubidium vapor cell. The central wavelength of the laser is resonant with the ${D}_{2}$ line of rubidium, and the peak intensity is in the ${10}^{12}$--${10}^{14}\phantom{\rule{4pt}{0ex}}\mathrm{W}/{\mathrm{cm}}^{2}$ range, enough to create a plasma channel with single-electron ionization. We observe the absorption of the laser pulse for low energy, a regime of transverse confinement of the laser beam by the strong resonant nonlinearity for higher energies and the transverse broadening of the output beam when the resonant nonlinearity ceases due to the valence electrons all being removed during ionization. We compare experimental observations of the transmitted pulse energy and the transverse fluence profile with the results of computer simulations modeling pulse propagation. We find a qualitative agreement between theory and experiment that corroborates the validity of our propagation model. While the quantitative differences are substantial, the results show that the model can be used to interpret the observed phenomena in terms of self-focusing and channeling of the laser pulses by the saturable, resonant nonlinearity.

Optical characterization of the on-target OMEGA focal spot at high energy using the full-beam in-tank diagnostic.

The full-beam in-tank (FBIT) diagnostic has been deployed to directly measure the target-plane beam fluence profile, when operated at high energy, of the OMEGA Laser System at the University of Rochester's Laboratory for Laser Energetics. This paper presents the results of early measurements taken with this diagnostic and discusses an improvement that has overcome performance limitations discovered during the initial testing. The diagnostic gives new insight into the ability of the OMEGA Laser System to provide uniform fluence profiles that are consistent across all 60 beams in the laser. The ultimate goal of the FBIT diagnostic is to allow accurate assessment of the fluence uniformity on a spherical target in 60-beam implosion experiments.

Characterization of megahertz X-ray laser beams by multishot desorption imprints in PMMA.

Proper diagnostics of intense free-electron laser (FEL) X-ray pulses is indisputably important for experimental data analysis as well as for the protection of beamline optical elements. New challenges for beam diagnostic methods are introduced by modern FEL facilities capable of delivering powerful pulses at megahertz (MHz) repetition rates. In this paper, we report the first characterization of a defocused MHz 13.5-nm beam generated by the free-electron laser in Hamburg (FLASH) using the method of multi-pulse desorption imprints in poly(methyl methacrylate)(PMMA). The beam fluence profile is reconstructed in a novel and highly accurate way that takes into account the nonlinear response of material removal to total dose delivered by multiple pulses. The algorithm is applied to experimental data of single-shot ablation imprints and multi-shot desorption imprints at both low (10 Hz) and high (1 MHz) repetition rates. Reconstructed response functions show a great agreement with the theoretical desorption response function model.

A comprehensive approach to the characterization of the deposited energy density during laser–matter interactions in liquids and solids

We present a novel approach to the characterization of ultrafast laser–matter interaction processes in solids and liquids under extreme conditions of microplasma generation. Through the combination of three-dimensional propagation imaging, absorption measurements, shadowgraphy and photoacoustic imaging we can restore plasma electron density distribution, laser pulse fluence profile and the value of deposited energy density inside the bulk of the material and characterize the regime of the laser pulse propagation. The developped concept is important for understanding the physics of ultrafast laser–matter interactions with strong implications for precision control of laser micromachining, bioprocessing and biotreatment.

Fluence-matching technique using photoacoustic radiofrequency spectra for improving estimates of oxygen saturation

Photoacoustic (PA) signals encode information about the optical absorption and spatial distribution of absorbing chromophores as well as the light distribution in the medium. The wavelength dependence of the latter affects the accuracy in chromophore quantification, including estimations of oxygen saturation (sO2) with depth. We propose the use of the ratio of the PA radiofrequency (RF) spectral slopes (SS) at different optical wavelengths to generate frequency filters which can be used to match the fluence profiles across separate images generated with different optical wavelengths.Proof-of-principle experiments were carried on a plastic tube with blood of a known oxygenation inserted into a porcine tissue. The algorithm was tested in-vivo in the hind leg of six CD1 mice, each under three different breathing conditions (100 % O2, room air and 100 % CO2). Imaging was done using the VevoLAZR system at the wavelengths 720 and 870 nm. The SS was calculated from the linear fit of the ratio of the photoacoustic RF power spectra at the two wavelengths. An ultrasound frequency filter was designed and applied to each segmented PA signal in the frequency domain and inversely transformed into the time domain to correct for the differences in the fluence profiles at both wavelengths. Linear spectral unmixing was used to estimate sO2 before and after applying the ultrasound frequency filter.The estimated blood sO2 in the plastic tube for the porcine tissue experiment improved by 10.3% after applying the frequency filter when compared to the sO2 measured by a blood gas analyzer. For the in-vivo mouse experiments, the applied sO2 correction was 2.67, 1.33 and -3.33% for every mm of muscle tissue for mice breathing 100% O2, room air and 100% CO2, respectively. The approach presented here provides a new approach for fluence matching that can potentially improve the accuracy of sO2 estimates by removing the fluence depth dependence at different optical wavelengths.

Investigating the impact of collimator size variation on the single beam radiation of Gamma Knife PerfexionTM based on Monte Carlo simulation

The Gamma Knife PerfexionTM (Elekta Oncology Systems) is a specialized stereotactic radiotherapy device that uses 192 Cobalt-60 radioactive sources. A dynamic collimator system enables three circular field sizes of 4 mm, 8 mm, and 16 mm diameter to be delivered. This study investigates the dosimetric characteristics of the three different sized collimated beams using Monte Carlo (MC) simulations. The MC simulation made use of previously calculated phase space from a Monte-Carlo model of the encapsulated Cobalt-60 sources. The collimators were modelled using the FLATFILT component module of the BEAMnrc user code. The output of the single beam radiation was stored in a circular scoring plane with a radius of 1.4 cm at source surface distance (SSD) 17.20 cm in the phase space file. The simulation parameters were used 2.1 x 109 particles, electron cut off energy (ECUT) of 0.7 MeV, and photon cut off energy (PCUT) of 0.01 MeV. To investigate the physical full width at half maximum (FWHM) and penumbra width (80-20%), the single beam profiles and mean energy were obtained using BEAMnrc/BEAMDP code. Based on the results that there was an increase of the full width at half maximum (FWHM) with the size of the collimator on the beam profile and the mean energy. The FHWM of the energy fluence profile for the collimator 4, 8, and 16 mm are 2.22, 3.90, and 7.80 mm, respectively. The FHWM of the fluence profile for the collimator sizes 4, 8, and 16 mm are 1.87, 3.87, and 7.80 mm. The FHWM of mean energy as a function of position for the collimator sizes 4, 8, and 16 mm are 2.56, 4.20, and 7.94 mm, respectively. The maximum mean energy for the collimators decreases as much as 0.0185 MeV.

Inferred UV fluence focal-spot profiles from soft x-ray pinhole-camera measurements on OMEGA.

A method was developed with laser-irradiated Au planar foils to characterize the focal spot of UV laser beams on a target at full energy from soft x-ray emission. A pinhole camera with a back-thinned charge-coupled device detector and filtration with thin Be and Al foil filters provides images of the x-ray emission at photon energies <2 keV. This method requires a careful measurement of the relationship between the applied UV fluence and the x-ray signal, which can be described by a power-law dependence. The measured exponent γ ∼ 2 provides a dynamic range of ∼25 for the inferred UV fluence. UV fluence profiles of selected beams were measured for 100-ps and 1-ns laser pulses and were compared to directly measured profiles from an UV equivalent-target-plane diagnostic. The inferred spot size and super-Gaussian order from the x-ray technique agree within several percent with the values measured with the direct UV measurements.

Automated prioritised 3D dose-based MLC segment generation for step-and-shoot IMRT

Segmentation can degrade a high-quality dose distribution obtained by fluence map optimisation (FMO). A novel algorithm is proposed for generation of MLC segments to deliver an FMO plan with step-and-shoot IMRT while minimising quality loss. All beams are considered simultaneously while generating MLC segments for reproducing the 3D FMO dose distribution. Segment generation is only steered by the 3D FMO dose distribution, i.e. underlying FMO fluence profiles are not considered. The algorithm features prioritised generation of segments, focusing on accurate reproduction of clinical objectives with the highest priorities. The performance of the segmentation algorithm was evaluated for 20 prostate patients, 15 head-and-neck patients, and 12 liver patients. FMO dose distributions were generated by automated multi-criteria treatment planning (Pareto-optimal plans) and subsequently segmented using the proposed method. Various segmentation strategies were investigated regarding prioritisation of objectives and limitation of the number of segments. Segmented plans were dosimetrically similar to FMO plans and for all patients a clinically acceptable segmented plan could be generated. Substantial differences between FMO and segmented fluence profiles were observed. Avoidance of the usual reconstruction of 2D FMO fluence profiles for segment generation, and instead simultaneously generating segments for all beams to directly reproduce the 3D FMO dose distribution is a likely explanation for the obtained results. For the strategies of limiting the number of segments large reductions in number of segments were observed with minimal impact on plan quality.