Artificial intelligence based deconvolving on megavoltage photon beam profiles for radiotherapy applications.

Objective. The aim of this work is an AI based approach to reduce the volume effect of ionization chambers used to measure high energy photon beams in radiotherapy. In particular for profile measurements, the air-filled volume leads to an inaccurate measurement of the penumbra.Approach. The AI-based approach presented in this study was trained with synthetic data intended to cover a wide range of realistic linear accelerator data. The synthetic data was created by randomly generating profiles and convolving them with the lateral response function of a Semiflex 3D ionization chamber. The neuronal network was implemented using the open source tensorflow.keras machine learning framework and a U-Net architecture. The approach was validated on three accelerator types (Varian TrueBeam, Elekta VersaHD, Siemens Artiste) at FF and FFF energies between 6 MV and 18 MV at three measurement depths. For each validation, a Semiflex 3D measurement was compared against a microDiamond measurement, and the AI processed Semiflex 3D measurement was compared against the microDiamond measurement.Main results. The AI approach was validated with dataset containing 306 profiles measured with Semiflex 3D ionization chamber and microDiamond. In 90% of the cases, the AI processed Semiflex 3D dataset agrees with the microDiamond dataset within 0.5 mm/2% gamma criterion. 77% of the AI processed Semiflex 3D measurements show a penumbra difference to the microDiamond of less than 0.5 mm, 99% of less than 1 mm.Significance. This AI approach is the first in the field of dosimetry which uses synthetic training data. Thus, the approach is able to cover a wide range of accelerators and the whole specified field size range of the ionization chamber. The application of the AI approach offers an quality improvement and time saving for measurements in the water phantom, in particular for large field sizes.

Supervised exercise training in peripheral arterial disease increases vascular shear stress and profunda femoral artery diameter.

Background Arteriogenesis is promoted by flow- and pressure-related forces such as tangential wall stress and laminar shear stress. Exercise training (ET) is known to promote arteriogenesis in peripheral arterial disease (PAD) patients. It remains unclear whether supervised ET (SET) promotes arteriogenesis more efficiently than non-SET (nSET). Methods and results Forty PAD patients participated in a SET or nSET training programme ( n = 20 each) and were compared to 20 healthy individuals without any history of cardiovascular events. Femoral artery diameter, flow and velocity were measured by ultrasound. Tangential wall stress and laminar shear stress were calculated for femoral arteries. Follow-up was performed after a mean of 7.65 ± 1.62 months. At follow-up, only the SET group showed a significant increase in lumen diameter of the profunda femoral artery ( p = 0.03), accompanied by an increase of tangential wall stress ( p = 0.002). Laminar shear stress decreased, but remained higher for the SET group compared to controls ( p < 0.01). Individual changes in walking distance were higher for SET patients ( p = 0.01) than nSET patients ( p = 0.07). Profunda femoral lumen diameter and tangential wall stress correlated directly with walking distance ( r = 0.446; p < 0.001), as well as with each other ( r = 0.743; p < 0.0001). Conclusions Our results indicate that SET promotes arteriogenesis more efficiently than nSET. Femoral lumen diameter and flow might help with the monitoring of ET efficiency and potential arteriogenesis.

Influence of exercise training on proangiogenic TIE-2 monocytes and circulating angiogenic cells in patients with peripheral arterial disease.

BACKGROUND: Inflammation is the driving force in atherosclerosis. One central strategy in the treatment of peripheral arterial disease (PAD) is the promotion of angiogenesis. Here, proangiogenic Tie-2 expressing monocytes (TEM) and circulating angiogenic cells (CAC) play a crucial role. Exercise training (ET) is recommended in PAD patients at Fontaine stage II to promote angiogenesis. METHODS: 40 patients with intermittend claudication (IC) [2 groups: supervised ET (SET) vs. non-supervised ET (nSET), each n = 20] and 20 healthy controls were included in the study. Analysis of TEM and CAC was performed from whole blood by flow-cytometry. TEM were identified via CD45, CD86, CD14, CD16 and analysed for the expression of Tie-2. CAC were identified via their expression of CD45 (CD45dim), CD34 and VEGF-R2 (CD309/KDR). Follow up was performed after mean of 7.65 ± 1.62 months. RESULTS: In comparison to healthy controls, we found increased proportions of CAC (p < 0.0001) and similar TEM numbers in both ET groups. At follow-up (FU) TEM poroportions increased (p < 0.001) and CAC proportions decreased (p < 0.01), but both more significantly in SET (p < 0.001) than nSET (p = 0.01). Only in SET fibrinogen levels decreased and VEGF-A increased (both p < 0.05). Finally, we found in both ET groups a significant increase in absolute walking distance but with a higher individual increase in SET (p < 0.01). TEM and CAC proportions correlated inversely with the absolute walking distance (CAC: r = -0.296, p = 0.02; TEM: r = -0.270, p = 0.04) as well as with ABI (CAC: r = -0.394, p < 0.01; TEM: r = -0.382, p < 0.01). CONCLUSIONS: ET influences the distribution of CAC and TEM proportions. nSET, although still effective in regard to an improved walking distance, is less effective in the influence of proangiogenic cells and inflammatory burden than SET. Our results indicate SET to be a more preferential exercise form, supporting the necessity to establish more SET programs.

Inflammation is associated with a reduced number of pro-angiogenic Tie-2 monocytes and endothelial progenitor cells in patients with critical limb ischemia.

BACKGROUND: Inflammation is the driving force in atherosclerosis. One central strategy in the treatment for PAD is the promotion of angiogenesis. Here, pro-angiogenic Tie-2-expressing monocytes (TEM) and endothelial progenitor cells (EPC) play a crucial role. Critical limb ischemia (CLI) is characterized by a severe, chronic inflammatory response; thus, progression of the disease might be related to the deleterious effects of inflammation on pro-angiogenic cells. METHODS: Forty-five patients with intermittent claudication (IC) [three groups: Rutherford (R)-1, -2, or -3; each n = 15], 20 patients with CLI [n = 20; Rutherford 4 (15 %), 5 (40 %), and 6 (45 %)], and 20 healthy controls were included in the study. Analysis of TEM and EPC was performed from whole blood by flow cytometry. Treatment for IC patients was conservative, and CLI patients underwent surgical revascularization. Follow-up was performed after mean of 7.1 months. RESULTS: In comparison with healthy controls, we found increased proportions of TEM and EPC in dependence of the severity of PAD, with the highest level in patients with severe claudication (R3) (p < 0.01). In contrast, for patients with CLI, we found a significantly reduced expression of both TEM and EPC in comparison with healthy controls (p < 0.05) or IC patients (R-1, R-2, and R-3) (all p < 0.001). At follow-up, TEM and EPC in CLI patients increased significantly (both p < 0.001). Serum levels of fibrinogen and CRP were significantly increased in CLI patients (all p < 0.001), but decreased at follow-up (all p < 0.05). TEM and EPC proportions correlated inversely with levels of fibrinogen [(TEM: r = −0.266; p < 0.01) (EPC: r = −0.297; p < 0.001)], CRP (TEM: r = −0.283; p < 0.01) (EPC: r = −0.260; p < 0.01). CONCLUSIONS: We found a strong association of diverse inflammatory markers with a reduced proportion of pro-angiogenic TEM or EPC in patients with CLI, giving rise to the speculation that a severe chronic inflammation might lead to deleterious effects on TEM and EPC, possibly interfering with angiogenesis, thus promoting an aggravation of the disease.

Severe life-threatening or disabling anaphylaxis in patients with systemic mastocytosis: a single-center experience.

BACKGROUND: Mediator-related symptoms in patients with systemic mastocytosis (SM) range from mild episodic to severe life-threatening events. METHODS: We examined a series of 137 consecutive patients with mastocytosis (63 females and 74 males) referred to our center between 1988 and 2010. Almost all patients received prophylactic histamine receptor (HR1 and HR2) antagonists. RESULTS: Forty-two patients suffered from one or more mediator-related symptoms (hypotension, headache, flush, abdominal cramping, diarrhea) requiring therapy (SM(SY)). Severe life-threatening events (grade IV) occurred in 17 patients (12%). In 4 of these 17 patients, a deteriorating clinical course was recorded. One patient died of an apallic syndrome 1.5 years after an hymenoptera sting and cerebral hypoxia. One patient was disabled for months after an insect sting and cerebral hypoxia. Two patients with smoldering SM (SSM) suffered from severe recurrent hypotension requiring hospitalization and repeated resuscitation. Symptoms in these SSM patients did not respond to any of the antimediator-type drugs applied. However, after therapy with cladribine (2CdA), a major durable response was obtained in both cases. In patients with aggressive SM and mast cell leukemia (n = 6), life-threatening mediator-related events (grade IV) were not recorded. CONCLUSIONS: SM may be accompanied by life-threatening mediator-related symptoms. Most of these patients have indolent SM or SSM. In patients with SSM(SY) with uncontrolled symptoms (grade IV), therapy with 2CdA should be considered.

Evaluation of the prognostic significance of eosinophilia and basophilia in a larger cohort of patients with myelodysplastic syndromes.

BACKGROUND: Lineage involvement and maturation arrest are considered to have prognostic significance in patients with myelodysplastic syndromes (MDS). However, although the prognostic value of neutropenia, thrombocytopenia, and monocytosis have been documented, little is known about the impact of eosinophils and basophils. METHODS: The authors examined the prognostic significance of eosinophils and basophils in 1008 patients with de novo MDS. Patients were enrolled from 3 centers of the Austrian-German MDS Working Group and were analyzed retrospectively. Blood eosinophils and basophils were quantified by light microscopy, and their impact on survival and leukemia-free survival was calculated by using Cox regression. RESULTS: Eosinophilia (eosinophils >350/microL) and basophilia (basophils >250/microL) predicted a significantly reduced survival (P < .05) without having a significant impact on leukemia-free survival. In multivariate analysis, eosinophilia and basophilia were identified as lactate dehydrogenase (LDH)-independent prognostic variables with International Prognostic Scoring System (IPSS)-specific impact. Although elevated LDH was identified as a major prognostic determinant in IPSS low-risk, intermediate-1 risk, and high-risk subgroups, the condition "eosinophilia and/or basophilia" was identified as a superior prognostic indicator in the IPSS intermediate-2 risk subgroup. CONCLUSIONS: The evaluation of eosinophils and basophils in patients with MDS was helpful and may complement the spectrum of variables to optimize prognostication in MDS.