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At least 19 recordsLinked to original sources
PubMed2002

[(C(wedge)N(wedge)N)Pt(C identical to C)nR] (HC(wedge)N(wedge)N = 6-aryl-2,2'-bipyridine, n = 1-4, R = aryl, SiMe3) as a new class of light-emitting materials and their applications in electrophosphorescent devices.

Tridentate cyclometalated platinum(II) complexes bearing sigma-alkynyl ligands exhibit tunable photoluminescence and enhanced stability during vacuum deposition; OLEDs based on these materials display orange to red electrophosphorescence with low turn-on voltages (approximately 4 V), maximum luminance approaching 10,000 cd m-2 and efficiency up to 4.2 cd A-1.

Journal Article↗
PubMed1997

Treatment planning of oblique wedge fields comparing enhanced dynamic wedge and standard 60 degree wedge for parotid type treatments.

The "standard" treatment planning for a parotid or similar treatment volume utilizes wedge field technique. This technique can be accomplished by using two beams on the same side of the patient with the heels of the wedges adjacent. This technique can also be accomplished by using standard or enhanced dynamic wedges. Advantages vs. disadvantages of enhanced dynamic wedged fields will be discussed in this paper.

Humans↗
PubMed2000

Optimizing beam weights and wedge filters with the concept of the super-omni wedge.

This study introduces a new concept, the super-omni wedge, and proposes an algorithm for optimizing beam weights, wedge angles, and wedge orientations on the basis of this new concept. The super-omni wedge is a generalization of the omni wedge. Instead of combining one open beam and two orthogonal wedged beams, it uses two orthogonal pairs of nominal wedged beams to generate a wedged dose distribution with an arbitrary wedge angle and an arbitrary wedge orientation. The orientations of a pair of nominal wedges are opposite each other. In this way, the effective wedge orientation can vary from 0 degrees to 360 degrees rather than being restricted to one quadrant. When the concept of the super-omni wedge is used, the optimization of beam weights, wedge angles, and wedge orientations for J beams is transformed into the optimization of beam weights for 4J beams. A quadratic dose-based objective function is defined, and the method of sequential quadratic programming is used to find the 4J beam weights that minimize it. After the weights of the nominal wedged beams have been determined, the beams can be delivered in one of four methods: Directly, by using the omni wedge technique, by using the universal wedge technique, and by using the virtual wedge technique. When tested with two clinical cases, the algorithm achieved homogeneous dose distributions in target volumes while meeting the constraints to the organs at risk. A prominent feature of the algorithm is that there is no need to manually preselect the orientations of nominal wedges.

Algorithms↗
PubMed2006

Anticancer cyclometalated [Au(III)m(C(wedge)N(wedge)C)mL]n+ compounds: Synthesis and cytotoxic properties.

A series of cyclometalated gold(III) compounds [Au(m)(C(wedge)N(wedge)C)mL]n+ (m = 1-3; n = 0-3; HC(wedge)N(wedge)CH = 2,6-diphenylpyridine) was prepared by ligand substitution reaction of L with N-donor or phosphine ligands. The [Au(m)(C(wedge)N(wedge)C)mL]n+ compounds are stable in solution in the presence of glutathione. Crystal structures of the gold(III) compounds containing bridging bi- and tridentate phosphino ligands reveal the presence of weak intramolecular pi pi stacking between the [Au(C(wedge)N(wedge)C)]+ units. Results of MTT assays demonstrated that the [Au(m)(C(wedge)N(wedge)C)mL]n+ compounds containing nontoxic N-donor auxiliary ligands (2) exert anticancer potency comparable to that of cisplatin, with IC50 values ranging from 1.5 to 84 microM. The use of [Au(C(wedge)N(wedge)C)(1-methylimidazole)]+ (2 a) as a model compound revealed that the gold(III)-induced cytotoxicity occurs through an apoptotic cell-death pathway. The cell-free interaction of 2 a with double-stranded DNA was also examined. Absorption titration showed that 2 a binds to calf-thymus DNA (ctDNA) with a binding constant of 4.5 x 10(5) dm3 mol(-1) at 298 K. Evidence from gel-mobility-shift assays and viscosity measurements supports an intercalating binding mode for the 2 a-DNA interaction. Cell-cycle analysis revealed that 2 a causes S-phase cell arrest after incubation for 24 and 48 hours. The cytotoxicity of 3 b-g toward cancer cells (IC50 = 0.04-4.3 microM) correlates to that of the metal-free phosphine ligands (IC50 = 0.1-38.0 microM), with [Au2(C(wedge)N(wedge)C)2(mu-dppp)]2+ (3 d) and dppp (dppp = 1,2-bis(diphenylphosphino)propane) being the most cytotoxic gold(III) and metal-free compounds, respectively. Compound 3 d shows a cytotoxicity at least ten-fold higher than the other gold(III) analogues; in vitro cellular-uptake experiments reveal similar absorptions for all the gold(III) compounds into nasopharyngeal carcinoma cells (SUNE1) (1.18-3.81 ng/cell; c.f., 3 d = 2.04 ng/cell), suggesting the presence of non-gold-mediated cytotoxicity. Unlike 2 a, both gold(III) compounds [Au(C(wedge)N(wedge)C)(PPh3)]+ (3 a) (PPh3 = triphenylphosphine) and [Au2(C(wedge)N(wedge)C)2(mu-dppp)]2+ (3 d) interact only weakly with ctDNA and do not arrest the cell cycle.

Antineoplastic Agents↗
PubMed2004

A practical method to calculate head scatter factors in wedged rectangular and irregular MLC shaped beams for external and internal wedges.

Factor based methods for absorbed dose or monitor unit calculations are often based on separate data sets for open and wedged beams. The determination of basic beam parameters can be rather time consuming, unless equivalent square methods are applied. When considering irregular wedged beams shaped with a multileaf collimator, parametrization methods for dosimetric quantities, e.g. output ratios or wedge factors as a function of field size and shape, become even more important. A practical method is presented to derive wedged output ratios in air (S(c,w)) for any rectangular field and for any irregular MLC shaped beam. This method was based on open field output ratios in air (S(c)) for a field with the same collimator setting, and a relation f(w) between S(c,w) and S(c). The relation f(w) can be determined from measured output ratios in air for a few open and wedged fields including the maximum wedged field size. The function f(w) and its parametrization were dependent on wedge angle and treatment head design, i.e. they were different for internal and external wedges. The proposed method was tested for rectangular wedged fields on three accelerators with internal wedges (GE, Elekta, BBC) and two accelerators with external wedges (Varian). For symmetric regular beams the average deviation between calculated and measured S(c,w) / S(c) ratios was 0.3% for external wedges and about 0.6% for internal wedges. Maximum deviations of 1.8% were obtained for elongated rectangular fields on the GE and ELEKTA linacs with an internal wedge. The same accuracy was achieved for irregular MLC shaped wedged beams on the accelerators with MLC and internal wedges (GE and Elekta), with an average deviation < 1% for the fields tested. The proposed method to determine output ratios in air for wedged beams from output ratios of open beams, combined with equivalent square approaches, can be easily integrated in empirical or semi-empirical methods for monitor unit calculations.

Algorithms↗
PubMed1997

Dose to the contralateral breast: a comparison of two techniques using the enhanced dynamic wedge versus a standard wedge.

The dose to the contralateral breast has been associated with an increased risk of developing a second breast malignancy. Varying techniques have been devised and described in the literature to minimize this dose. Metal beam modifiers such as standard wedges are used to improve the dose distribution in the treated breast, but unfortunately introduce an increased scatter dose outside the treatment field, in particular to the contralateral breast. The enhanced dynamic wedge is a means of remote wedging created by independently moving one collimator jaw through the treatment field during dose delivery. This study is an analysis of differing doses to the contralateral breast using two common clinical set-up techniques with the enhanced dynamic wedge versus the standard metal wedge. A tissue equivalent block (solid water), modeled to represent a typical breast outline, was designed as an insert in a Rando phantom to simulate a standard patient being treated for breast conservation. Tissue equivalent material was then used to complete the natural contour of the breast and to reproduce appropriate build-up and internal scatter. Thermoluminescent dosimeter (TLD) rods were placed at predetermined distances from the geometric beam's edge to measure the dose to the contralateral breast. A total of 35 locations were used with five TLDs in each location to verify the accuracy of the measured dose. The radiation techniques used were an isocentric set-up with co-planar, non divergent posterior borders and an isocentric set-up with a half beam block technique utilizing the asymmetric collimator jaw. Each technique used compensating wedges to optimize the dose distribution. A comparison of the dose to the contralateral breast was then made with the enhanced dynamic wedge vs. the standard metal wedge. The measurements revealed a significant reduction in the contralateral breast dose with the enhanced dynamic wedge compared to the standard metal wedge in both set-up techniques. The dose was measured at varying distances from the geometric field edge, ranging from 2 to 8 cm. The average dose with the enhanced dynamic wedge was 2.7-2.8%. The average dose with the standard wedge was 4.0-4.7%. Thermoluminescent dosimeter measurements suggest an increase in both scattered electrons and photons with metal wedges. The enhanced dynamic wedge is a practical clinical advance which improves the dose distribution in patients undergoing breast conservation while at the same time minimizing dose to the contralateral breast, thereby reducing the potential carcinogenic effects.

Breast↗
PubMed1995

Wedge factor changes with depth and field size on a linear accelerator with a motorized wedge.

The wedge factor was experimentally determined as a function of field size and phantom depth for 6-MV X-rays; measurements were performed on a linear accelerator with a motorized wedge filter (universal wedge, nominal wedge angle = 60 degrees). As a result of our experimental work, we can state that: 1) The wedge factor increases linearly with phantom depth (0.275%/cm), almost independent of field size; this change was experimentally related to the beam "hardening" caused by the high Z value of wedge material, as shown by the increase in wedged-field PDD with respect to the corresponding open-field PDD. Neglecting this variation can induce systematic errors in delivered dose, especially when deep-seated tumors are treated with wedge fields. 2) The wedge factor changes, for rectangular fields, according to the "equivalent square law", and not to the dimension in the wedged direction.

Filtration↗
PubMed1996

The omni wedge: a method to produce wedged fields at arbitrary orientations.

A method to produce wedged fields at any orientation relative to the collimator is described. The wedged field is generated by combining two appropriately weighted orthogonal wedged field segments at fixed collimator and gantry positions. The method requires only that wedged fields can be produced in orthogonal directions without rotating the collimator, such as is commonly provided on most radiation therapy accelerators by sets of standard and rotated wedges. Expressions are derived relating the effective wedge angle and orientation to the weighting and wedge angles of the orthogonal wedged field segments. This technique will be important when using multileaf collimator field shaping for which collimator rotation is dictated by target or critical structure shape and orientation. The term omni wedge is introduced to describe this technique.

Biophysical Phenomena↗
PubMed2006

Osteotomy for medial compartment arthritis of the knee using a closing wedge or an opening wedge controlled by a Puddu plate. A one-year randomised, controlled study.

A prospective, randomised, controlled trial compared two different techniques of high tibial osteotomy with a lateral closing wedge or a medial opening wedge, stabilised by a Puddu plate. The clinical outcome and radiological results were examined at one year. The primary outcome measure was the achievement of an overcorrection of valgus of 4 degrees . Secondary outcome measures were the severity of pain (visual analogue scale), knee function (Hospital for Special Surgery score), and walking distance. Between January 2001 and April 2004, 92 patients were randomised to one or other of the techniques. At follow-up at one year the post-operative hip-knee-ankle angle was 3.4 degrees (+/- 3.6 degrees SD) valgus after a closing wedge and 1.3 degrees (+/- 4.7 degrees SD) of valgus after an opening wedge. The adjusted mean difference of 2.1 degrees was significant (p = 0.02). The deviation from 4 degrees of valgus alignment was 2.7 degrees (+/- 2.4 degrees SD) in the closing wedge and 4.0 degrees (+/- 3.6 degrees sd) in the opening-wedge groups. The adjusted mean difference of 1.67 degrees was also significant (p = 0.01). The severity of pain, knee score and walking ability improved in both groups, but the difference was not significant. Because of pain, the staples required removal in 11 (23%) patients in the closing-wedge group and a Puddu plate was removed in 27 (60%) patients in the opening-wedge group. This difference was significant (p < 0.001). We conclude that closing-wedge osteotomy achieves a more accurate correction with less morbidity, although both techniques had improved the function of the knee at one year after the procedure.

Adult↗
PubMed1995

Evaluating the dose to the contralateral breast when using a dynamic wedge versus a regular wedge.

The incidence of secondary cancers in the contralateral breast after primary breast irradiation is several times higher than the incidence of first time breast cancer. Studies have shown that the scatter radiation to the contralateral breast may play a large part in the induction of secondary breast cancers. Factors that may contribute to the contralateral breast dose may include the use of blocks, the orientation of the field, and wedges. Reports have shown that the use of regular wedges, particularly for the medial tangential field, gives a significantly higher dose to the contralateral breast compared to an open field. This paper compares the peripheral dose outside the field using a regular wedge, a dynamic wedge, and an open field technique. The data collected consisted of measurements taken with patients, solid water and a Rando phantom using a Varian 2300CD linear accelerator. Ion chambers, thermoluminescent dosimeters (TLD), diodes, and films were the primary means for collecting the data. The measurements show that the peripheral dose outside the field using a dynamic wedge is close to that of open fields, and significantly lower than that of regular wedges. This information indicates that when using a medial wedge, a dynamic wedge should be used.

Breast↗
PubMed2003

Modelling the wedge shape for the virtual wedge.

We present a method to model the virtual wedge shape in a 3D treatment planning system as a physical wedge. The virtual wedge shape was determined using the measured dose profile of the virtual wedge at a chosen reference depth. The differences between the calculated and the measured dose profiles for the virtual wedge were within 0.5% at the reference depth, and within 2.5% at other depths. This method provides a fast and accurate way to implement the virtual wedge into our planning system for any wedge angles. This method is also applicable to model the physical wedge shapes with comparable good results.

Biophysical Phenomena↗
PubMed1994

Dosimetry of effective wedge fields produced by an internal wedge.

A procedure is described to calculate the monitor unit ratios required to produce effective wedge fields having a desired wedge angle by combining an internal 60 degrees wedge with an open field. Complementary procedures are derived and demonstrated for calculating the effective wedge dose distributions with wedge angles of 15 degrees, 30 degrees, and 45 degrees using the central axis depth dose data and off-axis ratios of the open field and the 60 degrees wedged field. Measurements at five points on and off the central axis within each field and measurements of the effective wedge factor demonstrated that the calculated wedge distributions were correctly delivered to within 2% in all cases.

Biophysical Phenomena↗
PubMed2005

[Fixation of proximal tibia medial opening wedge osteotomy using plates with wedges].

OBJECTIVES: The indications, surgical technique, and the results of fixation using plates with metal wedges were assessed in proximal tibia medial opening wedge osteotomy. METHODS: Forty knees in 38 consecutive patients (5 men, 33 women; mean age 51 years; range 36 to 65 years) with medial compartment osteoarthritis of the knee were treated with proximal tibia medial opening wedge osteotomy using plates with wedges. Following arthroscopic debridement, medial proximal tibial osteotomy was performed laterally and proximally on an oblique line and 3-4 cm distal to the medial joint space. Disruption of the lateral cortex was avoided. Fixation of the osteotomy was performed using plates with wedges. The plates which were designed by the author were either rectangular in shape with two or four holes or had an inverse "L" shape with four holes, bearing metal wedges at varying heights from 5 to 15 mm. The plates were fixed with screws. Tricortical (n=8) or bicortical (n=25) iliac bone autografts and allografts (n=7) were used. Clinical and functional evaluations were made using the HSS scoring system. The mean follow-up was 17 months (range 9 to 36 months). RESULTS: The mean preoperative and postoperative tibiofemoral angles were 4.3 degrees varus (0 degrees -10 degrees ) and 5.8 degrees valgus (3 degrees -11 degrees ), respectively. The mean HSS score increased from 59 (range 52 to 75) preoperatively to 90 (range 79 to 96) on final evaluations. During surgery, lateral tibial plateau fissures and lateral cortex fractures occurred in three (7.5%) and 11 (27.5%) knees, respectively. Delayed healing and delayed union and breakdown of a distal screw were encountered in one patient (2.5%). CONCLUSION: Fixation of proximal tibia medial opening wedge osteotomy using plates with wedges provides adequate stabilization to maintain the desired correction and to allow early functional rehabilitation in the treatment of medial osteoarthritis of the knee.

Adult↗
PubMed2006

Proximal tibia medial open-wedge osteotomy using plates with wedges: early results in 58 cases.

We evaluated in this study indications, surgical technique, and results of wedge plates for fixation in proximal tibia medial opening wedge osteotomy. Fifty-eight knees in 56 consecutive patients (9 men, 47 women; mean age 52 years; ranging between 36 and 66 years) with medial compartment osteoarthrosis were treated with proximal tibia medial open-wedge osteotomy. For fixation, plates which were designed by the first author and which support the osteotomy surface with wedge-shaped projections were used. The plates were either rectangular in shape with two or four holes or had an inverse "L" shape with four holes, and had bearing metal wedges of varying heights from 5 to 15 mm. Tricortical (n=8) and bicortical (n=43) iliac bone autografts and allografts (n=7) were used. The average follow-up time was 21 months (ranging between 6 and 44 months). The mean preoperative tibiofemoral angle was 4.6 degrees varus (0 degrees -11 degrees ) while it was 5.6 degrees valgus (2 degrees -11 degrees ) postoperatively. The mean preoperative HSS score was 58 (range 51-75) and it was found 89 (range 79-96) postoperatively. As complications, lateral tibial plateau fracture in 5 knees (8.6%) and lateral cortex fracture in 15 knees (25.8%) were encountered during surgery. Deep vein thrombosis in two cases (3.4%) and nonfatal pulmonary embolism in one case (1.7%), delayed wound healing in two knees (3.4%), and delayed union as well as breakdown of a distal screw in one knee (1.7%) were encountered postoperatively. In conclusion, using wedge plates for fixation of proximal tibia medial opening wedge osteotomy in the treatment of medial osteoarthritis with unicompartmental involvement of the knee, provides adequate stabilization to allow early movement for functional rehabilitation and keeps the obtained correction level.

Adult↗
PubMed1985

Effective wedge angles with a universal wedge.

Some recently designed x-ray-producing accelerators are equipped with a single built-in wedge, and different 'effective' wedge angles are obtained by combining an open (unwedged) and a wedged field in the appropriate proportions. This paper describes a technique for determining these proportions from measured isodose distributions of the two component fields. Our data for the Philips SL/75 6 MV accelerator are compared with two existing theoretical models. One model, in which the beams are weighted by the ratio of the tangents of the effective and nominal wedge angles, agrees with the data to within 3 degrees over the range of effective wedge angles and square field sizes examined. The second and simpler model, in which the beams are weighted by the ratio of the wedge angles directly, results in errors of as much as 11 degrees. It is shown that both of these models are approximations to an exact theoretical solution which may be formulated in terms of one free parameter. This parameter may be interpreted physically as the ratio of the slopes of the central-axis depth-dose curves for the open and wedged fields.

Humans↗
PubMed1988

Local variations of pulmonary arterial wedge pressure and wedge angiograms in patients with chronic lung disease.

This study was undertaken in 23 patients with chronic lung disease to determine whether local wedge pressure variability is related to the state of the local perfusion as observed in distal wedge angiograms. We also compared the variability of the pressures obtained after distal (mechanical) and proximal (balloon inflation) wedging of a catheter in three to six different sites in each patient. When the wedge pressure measurements were repeated in the same site (n = 7), the mean of the absolute differences was below 1 mm Hg. In individual patients, the maximal pressure difference between sites ranged from 0 to 6 mm Hg for Ppw and from 1 to 12 mm Hg for Pdw. The range in Pdw increased from normal to abnormal angiograms. These results suggest that when Pdw is high in one region, it may correspond to local perfusion abnormalities. When the wedge pressure is measured repeatedly or under different conditions, it should be determined after wedging the catheter in the same location for all of the periods of observation.

Bronchiectasis↗
PubMed2006

Experimental and numerical investigations on the dispersion behaviors of wedge waves propagating along wedges with bilinear cross sections.

Wedge waves (WW) are guided acoustic waves propagating along the tip of a wedge, with energy tightly confined near the apex. This study is focused on exploring the dispersion behaviors of WW propagating along a bilinear wedge (BW). A BW is wedge with a cross section of two apex angles, compared with a linear wedge (LW) having a single apex angle. In the literature, many studies regarding to the dispersion behaviors of ASF modes are reported for LW, but not for BW. In this study, a combined experimental and numerical stidy is used to investigate the dispersion behavior of WW propagating in BW's. It is found out that WW in a BW is a result of mode coupling between the two WW's corresponding to simple wedges with the two apex angles of the BW.

Journal Article↗