A protocol for absolute dose verification of SBRT/SRS treatment plans using Gafchromic™ EBT-XD films

PurposeTo provide a practical protocol for absolute dose verification of stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) treatment plans, based on our clinical experience. It aims to be a concise summary of the main aspects to be considered when establishing an accurate film dosimetry system.MethodsProcedures for film calibration and conversion to dose are described for a dosimetry system composed of Gafchromic™ EBT-XD films and a flatbed document scanner. Factors that affect the film-scanner response are also reviewed and accounted for. The accuracy of the proposed methodology was assessed by taking a set of strips irradiated to known doses and its applicability is illustrated for ten SBRT/SRS treatment plans. The film response was converted to dose using red and triple channel dosimetry. The agreement between the planned and measured dose distributions was evaluated using global gamma analysis with criteria of 3%/2mm 10% threshold (TH), 2%/2mm 10% TH, and 2%/2mm 20% TH.ResultsThe differences between the expected and determined doses from the strips analysis were 0.9 ± 0.6% for the red channel and 1.1 ± 0.7% for the triple channel method. Regarding the SBRT/SRS plans verification, the mean gamma passing rates were 99.5 ± 1.0% vs 99.6 ± 1.0% (3%/2mm 10% TH), 96.9 ± 3.5% vs 99.1 ± 1.3% (2%/2mm 10% TH) and 98.4 ± 1.8% vs 98.8 ± 1.5% (2%/2mm 20% TH) for red and triple channel dosimetry, respectively.ConclusionsThe proposed protocol allows for accurate absolute dose verification of SBRT/SRS treatment plans, applying both single and triple channel methods. It may work as a guide for users that intend to implement a film dosimetry system.     

Abdominal imaging dose in radiology and radiotherapy – Phantom point dose measurements,effective dose and secondary cancer risk

PurposeTo compare abdominal imaging dose from 3D imaging in radiology (standard/low-dose/dual-energy CT) and radiotherapy (planning CT, kV cone-beam CT (CBCT)).MethodsDose was measured by thermoluminescent dosimeters (TLD’s) placed at 86 positions in an anthropomorphic phantom. Point, organ and effective dose were assessed, and secondary cancer risk from imaging was estimated.ResultsOverall dose and mean organ dose comparisons yield significantly lower dose for the optimized radiology protocols (dual-source and care kV), with an average dose of 0.34±0.01 mGy and 0.54±0.01 mGy (average ± standard deviation), respectively. Standard abdominal CT and planning CT involve considerably higher dose (13.58 ± 0.18 mGy and 18.78±0.27 mGy, respectively). The CBCT dose show a dose fall-off near the field edges. On average, dose is reduced as compared with the planning or standard CT (3.79 ± 0.21 mGy for 220° rotation and 7.76 ± 0.37 mGy for 360°), unless the high-quality setting is chosen (20.30 ± 0.96 mGy). The mean organ doses show a similar behavior, which translates to the estimated secondary cancer risk. The modelled risk is in the range between 0.4 cases per million patient years (PY) for the radiological scans dual-energy and care kV, and 300 cases per million PY for the high-quality CBCT setting.ConclusionsModern radiotherapy imaging techniques (while much lower in dose than radiotherapy), involve considerably more dose to the patient than modern radiology techniques. Given the frequency of radiotherapy imaging, a further reduction in radiotherapy imaging dose appears to be both desirable and technically feasible.     

Monte Carlo calculation of photo-neutron dose produced by circular cones at 18 MV photon beams

Aim

The aim of this study is to calculate neutron contamination at the presence of circular cones irradiating by 18 MV photons using Monte Carlo code.

Study of the interaction of an α-helical transmembrane peptide with phosphatidylcholine bilayer membranes by means of densimetry and ultrasound velocimetry

We applied precise densimetry and ultrasound velocimetry methods to study the interaction of a synthetic α-helical transmembrane peptide, acetyl-K₂-L₂₄-K₂-amide (L₂₄), with model bilayer lipid membranes. The large unilamellar vesicles (LUVs) utilized were composed of a homologous series of n-saturated diacylphosphatidylcholines (PCs). PCs whose hydrocarbon chains contained from 13 to 16 carbon atoms, thus producing phospholipid bilayers of different thicknesses and gel to liquid-crystalline phase transition temperatures. This allowed us to analyze how the difference between the hydrophobic length of the peptide and the hydrophobic thickness of the lipid bilayer influences the thermodynamical and mechanical properties of the membranes. We showed that the incorporation of L₂₄ decreases the temperature and cooperativity of the main phase transition of all LUVs studied. The presence of L₂₄ in the bilayer also caused an increase of the specific volume and of the volume compressibility in the gel state bilayers. In the liquid crystalline state, the peptide decreases the specific volume at relatively higher peptide concentration (mole ratio L₂₄:PC = 1:50). The overall volume compressibility of the peptide-containing lipid bilayers in the liquid-crystalline state was in general higher in comparison with pure membranes. There was, however, a tendency for the volume compressibility of these lipid bilayers to decrease with higher peptide content in comparison with bilayers of lower peptide concentration. For one lipid composition, we also compared the thermodynamical and mechanical properties of LUVs and large multilamellar vesicles (MLVs) with and without L₂₄. As expected, a higher cooperativity of the changes of the thermodynamical and mechanical parameters took place for MLVs in comparison with LUVs. These results are in agreement with previously reported DSC and ²H NMR spectroscopy study of the interaction of the L₂₄ and structurally related peptides with phosphatidylcholine bilayers. An apparent discrepancy between ²H NMR spectroscopy and compressibility data in the liquid crystalline state may be connected with the complex and anisotropic nature of macroscopic mechanical properties of the membranes. The observed changes in membrane mechanical properties induced by the presence of L₂₄ suggest that around each peptide a distorted region exists that involves at least 2 layers of lipid molecules.     

Validation of a method for “dose of the day” calculation in head-neck tomotherapy by using planning ct-to-MVCT deformable image registration

PurposeThe aim of this study was to test the feasibility and dosimetric accuracy of a method that employs planning CT-to-MVCT deformable image registration (DIR) for calculation of the daily dose for head and neck (HN) patients treated with Helical Tomotherapy (HT).MethodsFor each patient, the planning kVCT (CTplan) was deformably registered to the MVCT acquired at the 15th therapy session (MV15) with a B-Spline Free Form algorithm using Mattes mutual information (open-source software 3D Slicer), resulting in a deformed CT (CTdef). On the same day as MVCT15, a kVCT was acquired with the patient in the same treatment position (CT15). The original HT plans were recalculated both on CTdef and CT15, and the corresponding dose distributions were compared; local dose differences <2% of the prescribed dose (DD2%) and 2D/3D gamma-index values (2%-2 mm) were assessed respectively with Mapcheck SNC Patient software (Sun Nuclear) and with 3D-Slicer.ResultsOn average, 87.9% ± 1.2% of voxels were found for DD2% (on average 27 slices available for each patient) and 94.6% ± 0.8% of points passed the 2D gamma analysis test while the 3D gamma test was satisfied in 94.8% ± 0.8% of body’s voxels.ConclusionsThis study represents the first demonstration of the dosimetric accuracy of kVCT-to-MVCT DIR for dose of the day computations. The suggested method is sufficiently fast and reliable to be used for daily delivered dose evaluations in clinical strategies for adaptive Tomotherapy of HN cancer.     

Identification of sterols and alcohols produced by green algae of the generaChlorella andScenedesmus by means of gas chromatography—mass spectrometry

Sterols and alcohols isolated from a collection of industrially important fresh-water green algaeChlorella kessleri, Scenedesmus acuminatus, S. acutus andS. acutus var.Tomasclli cultivated heterotrophically or autotrophically under pilot plant conditions, were identified and quantified by gas chromatography — mass spectrometry. Previsously demonstrated sterols with double bonds in position 5 and 7 were detected. In addition, cholesta-5,7,22-trien-3 β-oI that had not yet been described in green algae was found inS. acutus. Alcohols were found only inC. kessleri cultivated under heterotrophic conditions. Some saturated and unsaturated alcohols were detected for the first time in green algae.     

Metabolic fingerprinting of Leontopodium species (Asteraceae) by means of ¹H NMR and HPLC-ESI-MS

The genus Leontopodium, mainly distributed in Central and Eastern Asia, consists of ca. 34-58 different species. The European Leontopodium alpinum, commonly known as Edelweiss, has a long tradition in folk medicine. Recent research has resulted in the identification of prior unknown secondary metabolites, some of them with interesting biological activities. Despite this, nearly nothing is known about the Asian species of the genus. In this study, we applied proton nuclear magnetic resonance (1H NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS) metabolic fingerprinting to reveal insights into the metabolic patterns of 11 different Leontopodium species, and to conclude on their taxonomic relationship. Principal component analysis (PCA) of 1H NMR fingerprints revealed two species groups. Discriminators for these groups were identified as fatty acids and sucrose for group A, and ent-kaurenoic acid and derivatives thereof for group B. Five diterpenes together with one sesquiterpene were isolated from Leontopodium franchetii roots; the compounds were described for the first time for L. franchetii: ent-kaur-16-en-19-oic acid, methyl-15α-angeloyloxy-ent-kaur-16-en-19-oate, methyl-ent-kaur-16-en-19-oate, 8-acetoxymodhephene, 19-acetoxy-ent-kaur-16-ene, methyl-15β-angeloyloxy-16,17-epoxy-ent-kauran-19-oate. In addition, differences in the metabolic profile between collected and cultivated species could be observed using a partial least squares-discriminant analysis (PLS-DA). PCA of the LC-MS fingerprints revealed three groups. Discriminating signals were compared to literature data and identified as two bisabolane derivatives responsible for discrimination of group A and C, and one ent-kaurenoic acid derivative, discriminating group B. A taxonomic relationship between a previously unidentified species and L. franchetii and Leontopodium sinense could be determined by comparing NMR fingerprints. This finding supports recent molecular data. Furthermore, Leontopodium dedekensii and L. sinense, two closely related species in terms of morphology and DNA-fingerprints, could be distinguished clearly using 1H NMR and LC-MS metabolic fingerprinting.     

EPID-based daily verification of reproducibility of patients’ irradiation with IMRT plans

Aim

The aim of the work was to catch potential errors with daily EPID measurements of repeatability of the dose distribution during irradiation of IMRT patients.

An investigation into the solution structure of the single-stranded DNA undecamer 5′d AAGTGTGATAT by means of nuclear Overhauser enhancement measurements

A 500-MHz ¹H-NMR study on the single-stranded DNA undecamer (11-mer) 5d AAGTGTGATAT is presented. Using a combination of one-dimensional pre-steady-state nuclear Overhauser enhancement (NOE) measurements and two-dimensional homonuclear J-correlated spectroscopy, virtually complete resonance assignments are obtained. The relative magnitudes of the intra- and internucleotide NOEs indicate that the overall structure of the single-stranded 11-mer is a right-handed B-type helix with extensive base stacking. Within this overall structure there is quite a large degree of variability, as exemplified by variations in glycosidic bond and sugar pucker conformations, most likely determined by base sequence.Abbreviations NOE nuclear Overhauser effect - COSY twodimensional homonuclear J-correlated spectroscopy - 11-mer undecamer - EDTA sodium ethylenediamine tetraacetate - HPLC nigh-pressure liquid chromatography - DSS 4,4-dimethylsilapentane-1-sulfonate     

In vivo fertilizing ability of stallion spermatozoa processed by single layer centrifugation with Androcoll-E™

A colloid with a species specific silane-coated, silica-based formulation, optimized for stallion (Androcoll-E™), enables a better sub-population of spermatozoa to be selected from stallion ejaculates. However, such a practice has not been critically evaluated in stallions with fertility problems. In this study we evaluate whether single-layer centrifugation (SLC) through Androcoll-E™ could be used to enhance fertility rates in a subfertile stallion. Ejaculates were obtained from two different stallions, one Lusitano (fertile) and one Sorraia (subfertile), with distinct sperm characteristics and fertility. Motility, morphology, plasma membrane structural (eosin-nigrosin) and functional integrity (HOS test), mitochondrial functionality (Δψm; JC-1) and longevity (motility after 72 h cooling) after centrifugation in Androcoll-E™, as well as pregnancy rates obtained after artificial insemination (AI), with and without (control group) SLC-treated sperm were assessed. The effect of SLC on sperm characteristics, and fertility results were evaluated by ANOVA and Fisher procedures, respectively. Our results showed that SLC-selected sperm did not differ from the raw semen in terms of viability, morphology, response to hypo-osmotic conditions (HOS test) and mitochondrial membrane potential (↑ΔΨmit; JC-1). Sperm motility in cooled samples was not improved by SLC treatment. Our data show that SLC through Androcoll-E™ has no effect on pregnancy rates in the stallions used in this trial.     

Assessing genetic diversity of Citrus by DArT_seq™ genotyping

In citrus despite the diversity among cultivated genotypes related to morphological, physiological, and agronomic traits, low polymorphism is detected at the molecular marker level, and the number of DNA-markers technologies has been insufficient to identify genetic diversity among all citrus varieties. However, DArT_seq? markers can overcome this limitation and identify genetic diversity in several species of citrus. This work developed and applied DArT_seq? platform to study the relationships among species, cultivars, and hybrids of citrus. DArT_seq? yielded a total of 37,260 polymorphic presence/absence markers that generated a dendrogram of similarity among the studied genotypes. The results confirmed the relationships of sweet orange, mandarin, and citron species. DArT_seq? markers showed extensive genetic variation among citrus species and can be applied to Citrus genetic diversity studies.     

Cellular delivery and enhanced anticancer activity of berberine complexed with a cationic derivative of γ–cyclodextrin

A cationic derivative of γ-cyclodextrin (GCD) modified with propylenediamine (PDA) was synthesized. It was shown that the derivative (GCD–PDA) is mucoadhesive and resistant to the digestion with?∝-amylase indicating that it may constitute an efficient oral delivery vehicle. GCD-PDA formed an inclusion complex with berberine (BBR), an alkaloid displaying a multitude of beneficial physiological effects. The complexed BBR penetrates a lipid membrane easier than the free one. Both uncomplexed BBR and that complexed with GCD-PDA was delivered to normal (NMuMG) and cancerous (4T1) murine mammary gland cells. In the normal cells both free and complexed BBR was homogeneously dispersed in the cytoplasm and was nontoxic up to 131?μM. In the cancerous cells uncomplexed BBR was also homogeneously dispersed but it was toxic to about 25% of cells at 131?μM, while the GCD-PDA/BBR complex was preferably localized in lysosomes and its toxicity doubled at this concentration compared to that of free BBR. Moreover, free BBR and GCD-PDA/BBR showed even more efficient inhibitory effect against murine melanoma (B16-F10) cells than against 4T1 cells.     

Pretreatment with a combination of quercetin and α-tocopherol ameliorates adenosine triphosphatases and lysosomal enzymes in myocardial infarcted rats

AimsMembrane bound adenosine triphosphatases (ATPases) and lysosomal enzymes play an important role in the pathology of myocardial infarction. This study was aimed to evaluate the combined preventive effects of quercetin and α-tocopherol on membrane bound ATPases and lysosomal enzymes in isoproterenol induced myocardial infarcted rats.Main methodsMale Wistar rats were pretreated with a combination of quercetin (10 mg/kg) and α-tocopherol (10 mg/kg) daily for 14 days. After the pretreatment period, isoproterenol (100 mg/kg) was injected to rats at an interval of 24 h for two days to induce myocardial infarction. The activities of ATPases and lysosomal enzymes were assayed.Key findingsIsoproterenol treated rats showed decreased levels of heart creatine kinase and lactate dehydrogenase. The activity of sodium potassium adenosine triphosphatase was decreased and the activities of magnesium adenosine triphosphatase and calcium adenosine triphosphatase were increased in isoproterenol treated rats. Also, the activities of β-glucuronidase, β-N-acetylglucosaminidase, β-galactosidase, cathepsin-B and D were increased (serum and heart), but the activities of β-glucuronidase and cathepsin-D were decreased in lysosomal fraction and increased in cytosolic fraction of the heart in isoproterenol treated rats. Furthermore, the heart lipid peroxidation products were increased in isoproterenol treated rats. Combined pretreatment with quercetin and α-tocopherol to isoproterenol treated rats normalized all the biochemical parameters studied. The observed effects are due to their membrane stabilizing property and this property might be due to decreased lipid peroxidation.SignificanceOur study demonstrated that combined pretreatment was better than single pretreatment. This study may have significant impact on myocardial infarcted patients.     

Enhanced crocetin glucosylation by means of maltosyl-β-cyclodextrin encapsulation

Summary The water-soluble solvent dimethylsulfoxide proved to be inhibitory to the enzymatic glucosylation of crocetin catalyzed by cell-free extracts of saffron (Crocus sativus L.) callus cultures. This problem was circumvented by encapsulating crocetin into maltosyl--cyclodextrin at a 1:3 and a 1:6 ratio which made it possible to carry out the reaction with up to 1,750 and 2,500 M crocetin respectively.     

Isolation of protoplasts by means of a “species-specific” autolysine inChlamydomonas

Summary Prior to fusion, gametes ofChlamydomonas reinhardii discard their cell walls. This naturally occuring phenomenon has provided the basis for a method of protoplast isolation from both gametes and vegetative cells within the genusChlamydomonas. When synchronized cultures of compatibleChlamydomonas gametes are mixed it is possible, after removal of the cells, to obtain a solution having a high cell wall lytic activity. That vegetative and gamete cells after treatment with this gamete-autolysine are indeed protoplasts has been proved by various light and electron microscopical methods.The species specifity of this autolysine, its difference to the previously described sporangialautolysine (Schlösser 1966) and furthermore its use in the large scale production of protoplasts is also described. Since this wall autolysine is a factor produced by the cells themselves at a particular stage in their life cycle it represents a non-foreign agent in contrast to all other enzymic methods previously employed for protoplast isolation.     

Evaluation of glycoconjugates on the K562 cell surface by means of lectin binding — comparison with human erythrocytes

The binding of five radiolabelled lectins (Vicia graminea, peanut,Phaseolus vulgaris isolectins E-PHA and L-PHA,Evonymus europaeus) to untreated and desialylated K562 cells and human erythrocytes was compared. The number of glycophorin A receptors recognized on the K562 cells by anti-blood group NV. graminea lectin was comparable to that found on the MN or NN erythrocyte surface. However, K562 cells had a severalfold higher number of oligosaccharide chains (presumablyO-glycosidic) which after desialylation became high-affinity receptors for peanut agglutinin, and of complex typeN-glycosidic chains available for the reaction with E-PHA and also with L-PHA (the latter lectin was not bound to erythrocytes). Moreover, K562 cells not treated with neuraminidase had a significant amount of extremely low affinity receptors for peanut agglutinin, whereas binding of this lectin to untreated erythrocytes was undetectable. On the other hand, the untreated K562 cells did not bind anti-blood group B and HE. europaeus lectin, but a small amount of binding by the desialylated cells was observed. Some other differences observed in the mode of lectin binding to K562 cells and erythrocytes are discussed.     

Immobilization of enzymes on alumina by means of pyridoxal 5′-phosphate

A number of proteases have been immobilized on alumina in a two-step procedure: the first step converted them into semisynthetic phosphoproteins which, in the second step, spontaneously bonded to alumina through their phosphate function. The immobilized enzymes thus obtained showed the physical properties typical of the inorganic carrier and a high activity on low molecular weight substrates.