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PubMed1998

Calculating dose distributions and wedge factors for photon treatment fields with dynamic wedges based on a convolution/superposition method.

A convolution/superposition based method was developed to calculate dose distributions and wedge factors in photon treatment fields generated by dynamic wedges. This algorithm used a dual source photon beam model that accounted for both primary photons from the target and secondary photons scattered from the machine head. The segmented treatment tables (STT) were used to calculate realistic photon fluence distributions in the wedged fields. The inclusion of the extra-focal photons resulted in more accurate dose calculation in high dose gradient regions, particularly in the beam penumbra. The wedge factors calculated using the convolution method were also compared to the measured data and showed good agreement within 0.5%. The wedge factor varied significantly with the field width along the moving jaw direction, but not along the static jaw or the depth direction. This variation was found to be determined by the ending position of the moving jaw, or the STT of the dynamic wedge. In conclusion, the convolution method proposed in this work can be used to accurately compute dose for a dynamic or an intensity modulated treatment based on the fluence modulation in the treatment field.

Humans↗

PubMed1999

The 'equivalent wedge' implementation of the Varian Enhanced Dynamic Wedge (EDW) into a treatment planning system.

The purpose of this work was to establish procedures for the implementation of the Varian Enhanced Dynamic Wedge into a treatment planning system (TPS), based as much as possible on simple theoretical considerations and already available data. A method is presented for the calculation (rather than measurement) of off-axis relative wedge transmission curves that are required by the TPS for relative dose calculations. We also present a method for absolute dose (monitor unit) calculations, based on the calculation of an effective wedge factor on the prescription point. A simple formula has been derived for the calculation of the effective wedge factor for the most general case, i.e. an arbitrary effective wedge angle, field size and prescription point. Relative dose calculations have been verified by measurements performed on a Varian Clinac 2300C/D linear accelerator, for 6 MV and 20 MV photon energies. Monitor unit calculations have also been verified experimentally for several cases such as symmetric and asymmetric fields with prescription on the collimator axis or on the geometrical centre of the asymmetric field. The presented technique provides results within 2% for both relative and absolute dose calculations for clinically relevant cases.

Algorithms↗

PubMedDate not supplied

Effective wedge angles for 6-MV wedges.

Measurements were undertaken with 30 degrees and 45 degrees large wedges on a 6-MV linac to determine the effective wedge angle for various combinations of open and wedged fields. The validity of Tatcher's equation, relating effective wedge angle to maximum dose weightings, was examined over a range of field sizes from 5 X 5 to 20 X 20 cm. An alternative equation involving only central axis quantities was also investigated. The results obtained from an analysis of point dose measurements indicate that, for these wedges, either equation yields sufficient accuracy for clinical purposes.

Animals↗

PubMed1992

[Cement wedge replacing iliac graft in tibial wedge osteotomy].

The authors report their experience in substituting cement for full-thickness iliac crest wedge in medial tibial wedge osteotomy using buttress plate fixation. A review of 107 osteotomies performed between January 1985 and March 1989, demonstrated that using cement wedge do not expose to any special complication and raise the accuracy of frontal mechanical axes correction. At last, cement wedge seems not to evolve as a stranger corpus able to give long or mean terms complications; it perhaps make unnecessary bone substitute or allografts wedges.

Adult↗

PubMed2004

A six-month followup of a randomized trial comparing the efficacy of a lateral-wedge insole with subtalar strapping and an in-shoe lateral-wedge insole in patients with varus deformity osteoarthritis of the knee.

OBJECTIVE: To assess the effect of a lateral-wedge insole with elastic strapping of the subtalar joint on the femorotibial angle in patients with varus deformity of the knee. METHODS: The efficacy of a wedged insole with subtalar straps and that of a traditional wedged insole shoe insert were compared. Sixty-six female outpatients with knee osteoarthritis (OA) were randomized (according to birth date) to be treated with either the strapped or the traditional inserted insole. Standing radiographs with unilateral insole use were used to analyze the femorotibial angles for each patient. In both groups, the baseline and 6-month visual analog scale (VAS) scores for subjective knee pain and the Lequesne index scores for knee OA were compared. RESULTS: The 61 patients who completed the 6-month study were evaluated. At baseline, there was no significant difference in the femorotibial angle (P = 0.66) and the VAS score (P = 0.75) between the 2 groups. At the 6-month assessment, the 29 subjects wearing the subtalar-strapped insole demonstrated a significantly decreased femorotibial angle (P < 0.0001) and significantly improved VAS scores (P = 0.001) and Lequesne index scores (P = 0.033) compared with their baseline assessments. These significant differences were not observed in the 32 subjects assigned to the traditional shoe-inserted wedged insole. CONCLUSION: These results suggest that an insole with a subtalar strap maintained the valgus correction of the femorotibial angle in patients with varus knee OA for 6 months, indicating longer-term clinical improvement with the strapped insert compared with the traditional insert.

Aged↗

PubMed2004

Tricalcium phosphate granules or rigid wedge preforms in open wedge high tibial osteotomy: a radiological study with a new evaluation system.

The capacity of two forms of porous beta-tricalcium phosphate bone substitutes (TCP) to promote bone healing in open wedge high tibial osteotomy (OWHTO) was studied. We reviewed the X-rays of 27 osteotomies, with either TCP wedges or TCP granules as filling material, to compare the bone healing rates and bone remodelling, at specific postoperative intervals. A new radiologic rating system for OWHTO was created and tested for clinical applicability. All osteotomies healed uneventfully and complete resorption of TCP was demonstrated at 1 year postoperative in 85% (n = 23) of the procedures. In 44% (n = 10) of these 23 procedures, the osteotomy site was no longer visible. No difference in bone healing rate and bone remodelling was found when comparing the use of granules to a wedge, and no adverse effects of TCP were observed. The good inter- (k = 0.7) and intraobserver (k = 0.6) reliability of the new radiologic rating system enables clinical use. Good bone healing was found in OWHTO with both wedges and granules of TCP.

Adult↗

PubMed2004

[Biphasic ceramic wedge and plate fixation with locked adjustable screws for open wedge tibial osteotomy].

PURPOSE OF THE STUDY: The aim of this radiological study was to evaluate the use of a biphasic ceramic wedge combined with plate fixation with locked adjustable screws for open wedge tibial osteotomy. MATERIAL AND METHODS: Twenty-six consecutive patients (27 knees) underwent surgery between December 1999 and March 2002 to establish a normal lower-limb axis. The series included 6 women and 20 men, mean age 50 years (16 right knees and 11 left knees). Partial weight-bearing with crutches was allowed on day 1. A standard radiological assessment was performed on day 1, 90, and 360 (plain AP and lateral stance films of the knee). A pangonogram was performed before surgery and at day 360. Presence of a lateral metaphyseal space, development of peripheral cortical bridges, and osteointegration of the bone substitute-bone interface were evaluated used to assess bone healing. The medial tibial angle between the line tangent to the tibial plateau and the anatomic axis of the tibia (beta) was evaluated to assess preservation of postoperative correction. The HKA angle was determined. RESULTS: Three patients were lost to follow-up and 23 patients (24 knees) were retained for analysis. At last follow-up, presence of peripheral cortical bridges and complete filling of the lateral metaphyseal space demonstrated bone healing in all patients. Good quality osteointegration was achieved since 21 knees did not present an interface between the bone substitute and native bone (homogeneous transition zone). The beta angle was unchanged for 23 knees. A normal axis was observed in patients (16 knees) postoperatively. DISCUSSION: Use of a biphasic ceramic wedge in combination with plate fixation with locked adjustable screws is a reliable option for open wedge tibial osteotomy. The bone substitute fills the gap well. Tolerance and integration are optimal. Bone healing is achieved. Plate fixation with protected weight bearing appears to be a solid assembly, maintaining these corrections.

Adult↗

PubMed1995

Radiotherapy treatment planning with dynamic wedges--an algorithm for generating wedge factors and beam data.

If the jaws of a linear accelerator are moved under computer control during irradiation, dose distributions similar to those with wedge filters can be produced. Varian linear accelerators utilize this effect to give a 'dynamic wedge', using segmented treatment tables (STTs). An algorithm is described to generate the dose per monitor unit at any point in a beam, using the STT values. Dynamically wedged beams are modelled as the superposition of static asymmetric beams, using an algorithm based on beam data measured for symmetric beams. Predictions of wedge factors, depth doses and profiles generated using the algorithm are compared with measurements. Good agreement is found between predictions and measurements. The calculation time is typically 5 ms/dose point on a PC with a 486DX processor.

Algorithms↗

PubMed1975

[Electron therapy using wedge filters. I. Experimental studies using wedge filters made from polystyrol].

Based on dose measurements at the phantom, the dose distributions obtained during electron therapy by the use of wedge filters made of polystyrol are reported. Energy doses from 15 to 42 MeV were applied; angles of wedges amounted to 10 degrees, 30 degrees, 45 degrees, and 60 degrees. Only by wedge-angles larger than 45 degrees, it was possible to bring about significant changes in the dose distribution. The results obtained are presented diagrammatically. The influence exerted by the wedge-angle and by electron energy upon the inclination of the 50%-isodose to the axis of the useful beam is shown by tables.

Electrons↗

PubMed1984

Wedge pulmonary angiography to determine the accuracy of pulmonary wedge pressure.

Wedge pulmonary angiography was done in 11 patients with acute respiratory failure, to assess the accuracy of pulmonary arterial wedge pressure (WP) as an estimation of left ventricular end-diastolic pressure (LVEDP). The pulmonary artery (PA) catheter tip was placed into a dependent position in the lungs. Although the pulmonary vein was not visualized in 7 of 11 patients, in no case was there a significant difference between WP and LVEDP. When WP is no greater than 15 mm Hg, wedge pulmonary angiography does not reflect the accuracy of WP; however, left ventricular filling pressure can be accurately estimated by WP in most of these patients.

Acute Disease↗

PubMed2005

A 2-year follow-up of a study to compare the efficacy of lateral wedged insoles with subtalar strapping and in-shoe lateral wedged insoles in patients with varus deformity osteoarthritis of the knee.

OBJECTIVE: This study was conducted in order to assess the effect of wearing a lateral wedged insole with a subtalar strap for 2 years in patients with osteoarthritis varus deformity of the knee (knee OA). DESIGN: The setting was an outpatient clinic. The efficacies of the strapped insole and a traditional shoe insert wedged insole (the inserted insole), as a positive control, were compared at the baseline and after 2 years of treatment. Randomization was performed according to birth date. The 61 female outpatients with knee OA who completed a prior 6-month study were asked to wear their respective insoles continuously as treatment during the course of the 2-year study. The femorotibial angle (FTA) was assessed by standing radiographs obtained while the subjects were barefoot and the Lequesne index of the knee OA at 2 years was compared with those at baseline in each insole group. RESULTS: There were 61 patients in the original study, but 13 patients (21.3%) did not want to wear the insole continuously and five (8.2%) withdrew for other reasons. The 42 patients who completed the 2-year study were evaluated. At the 2-year assessment, participants wearing the subtalar strapped insole (n=21) demonstrated significantly decreased FTA (P=0.015), and significantly improved Lequesne index (P=0.031) in comparison with their baseline assessments. These significant differences were not found in the group with the traditional shoe inserted wedged insole (n=21). CONCLUSION: Only those participants using the subtalar strapped insole demonstrated significant change in the FTA in comparison with the baseline assessments. If the insole with a subtalar strap maintains FTA for more than 2 years, it may restrict the progression of degenerative articular cartilage lesions of knee OA.

Aged↗

PubMed2001

New bone formation around porous hydroxyapatite wedge implanted in opening wedge high tibial osteotomy in patients with osteoarthritis.

A porous hydroxyapatite (highly purified synthetic Ca10(PO4)6(OH)2) wedge was inserted into the tibia in 10 knees of 7 patients with osteoarthritis of the knee who underwent high tibial osteotomy. The interface of this HA wedge with bone was histologically examined in undecalcified specimens obtained at the time of hardware removal in all 10 knees, and total incorporation of the HA into bone was observed, with no inflammatory reaction. The proportion of pores that were filled with regenerated bone within 300 microm from the interface was 71.8 +/- 10.1% (mean +/- S.D.), and it was positively correlated with the time from implantation to biopsy. Radiodensity of the HA wedge was measured during the follow-up period, and it did not change significantly within 36 months after osteotomy. Our study concluded that bone ingrowth into the HA block slowly progressed and was correlated with the passage of time.

Aged↗

PubMedDate not supplied

Treatment of residual clubfoot deformity--the "bean-shaped" foot--by opening wedge medial cuneiform osteotomy and closing wedge cuboid osteotomy. Clinical review and cadaver correlations.

Six patients (seven feet) previously treated surgically for clubfoot had a "bean-shaped" foot. Opening wedge medial cuneiform and closing wedge cuboid osteotomies were done, resulting in good resolution of the prominent midfoot supination and forefoot adductus without significant soft tissue dissection and invasion of growing areas in the foot. Cadaver reproductions show that the cuboid closing wedge is responsible for the change in the midfoot, whereas the cuboid and cuneiform osteotomies both contribute to the change in the forefoot.

Cadaver↗

PubMed2006

The effects of intrafraction motion on dose homogeneity in a breast phantom with physical wedges, enhanced dynamic wedges, and ssIMRT.

PURPOSE: This study attempts to compare how breathing motion affects intact-breast cancer patients between three different treatment techniques and to determine the degree of improvement on dose homogeneity when implementing gating therapy. METHODS AND MATERIALS: A breast phantom and respiratory simulator were designed to simulate respiratory motion to a first-order approximation. Film was used as a dosimeter, and static dosimetry data were used as a control for comparison. Three velocities of the breast phantom were studied, and gating therapy was introduced for each data set. Dose area histograms (DAHs) were calculated for a breast and a "lung" planning target area (PTA), and Normalized Agreement Test (NAT) indices were calculated in reference to the static case. RESULTS: Deviations from the static case were highest if the collimator speed was of the same magnitude as the speed of the target. In general, gating therapy improved dose uniformity to the breast PTA by up to 14% and reduced dose to the "lung" PTA by up to 24%. With step-and-shoot intensity-modulated radiation therapy (ssIMRT), gating the beam may compromise dose coverage of the breast PTA if the timing interval of the gate is too large. Gating the beam decreased NAT indices by 9 for physical wedges, by 16 for enhanced dynamic wedges, and by 6 for ssIMRT. CONCLUSIONS: Both the phantom and respiratory simulator are adequate for showing differences in dose distributions for all three treatment modalities. Gating therapy improves dose homogeneity to the PTAs and decreases the dose delivered to areas below the posterior border of the beams.

Breast↗

PubMed2005

Synthesis, characterization, and photophysical properties of Os(II) diimine complexes [Os(N(wedge)N)(CO)(2)I(2)] (N(wedge)N = bipyridine, phenanthroline, and pyridyl benzoxazole).

A new series of Os(II) diimine complexes with the general formula [Os(N(wedge)N)(CO)(2)I(2)], N(wedge)N = 2,2'-bipyridine (bpy) (1), 4,4'-di-tert-butyl-2,2'-bipyridine (dbubpy) (2), 4,7-diphenyl-1,10-phenanthroline (dpphen) (3), 2-(2'-pyridyl)benzoxazole (pboz) (4), and 5-tert-butyl-2-(2'-pyridyl)benzoxazole (bupboz) (5), were synthesized and characterized by spectroscopic methods and by a single-crystal X-ray diffraction study on the dpphen complex 3. The corresponding photophysical properties were studied using UV-vis and emission spectrometry. The resulting phosphorescence features both in solution and as a solid film, in combination with the MO calculation, lead us to conclude that the emissions originate from mixed halide-to-ligand (XLCT approximately 70%) and metal-to-ligand (MLCT approximately 30%) transitions instead of the typical MLCT transition. Using complexes 4 and 5 as the dopant emitters, we evaluated their potential to serve as a phosphor for organic light emitting diodes by examining their electroluminescent performances. Reddish orange electroluminescence centered around 600 nm was observed for organic light emitting diodes (OLEDs) fabricated using complex 5 as the emitter; the device efficiency was shown to be as high as 2.8% (and 5.0 cd/A or 2.7 lm/W), and the peak luminance was shown to be 5600 cd/m(2) at a driving voltage of approximately 15 V.

Journal Article↗

PubMed2005

Excited states of phosphorescent platinum(II) complexes containing N wedge C wedge N-coordinating tridentate ligands: spectroscopic investigations and time-dependent density functional theory calculations.

The absorption and emission spectra of the Pt(II) complexes containing N wedge C wedge N-coordinating tridentate ligands, platinum(II) 1,3-di(2-pyridyl)benzene chloride [Pt(dpb)Cl] and platinum(II) 3,5-di(2-pyridyl)toluene chloride [Pt(dpt)Cl], together with their corresponding free ligands, 1,3-di(2-pyridyl)benzene (dpbH) and 3,5-di(2-pyridyl)toluene (dptH), have been analyzed by density functional theory (DFT) for the ground state and time-dependent DFT (TDDFT) for the excited states. T(1)(A(1)) and S(1)(B(2)) of the complexes (in C(2)(v) symmetry) were assigned on the basis of the calculated excitation energies as well as comparison of the experimental spectroscopic properties and the calculated states' characteristics. The calculated excitation energies for T(1) and S(1) of the complexes as well as those for T(1) of the free ligands were in good agreement with their observed values within 600 cm(-1). The d-pi* characters of the excited states were evaluated from the change in electron densities between the ground and excited states by Mulliken population analysis; values of 25% for T(1) and 32% for S(1) were obtained for both complexes. The calculated values of d-pi* character were found to be consistent with the reported emission lifetimes as well as the observed emission energy shifts from the corresponding free ligands. Most spectroscopic properties of the complexes and the free ligands, which include solvatochromic shift, Stokes shifts, methyl substitution shifts, and emission spectra profiles, were well explained from the calculation results.

Journal Article↗

PubMed2006

Long-term outcome of laparoscopic wedge resection for gastric submucosal tumor compared with open wedge resection.

Little is known about the outcomes of laparoscopic wedge resection (LWR) in comparison with conventional open wedge resection (OWR) for gastric submucosal tumor. Outcomes of 21 patients who underwent LWR (n = 14) or OWR (n = 7) for gastric submucosal tumor between 1993 and 2004 were investigated. We compared the short-term and long-term operative results between the 2 groups. LWR showed several advantages over OWR for gastric submucosal tumor: less blood loss, lower fever on day 1, lower analgesic usage rate, earlier first postoperative flatus and oral intake, lower leukocyte count on days 1 and 7, and lower C-reactive protein level on days 1 and 3. All patients, except 2 with histologically diagnosed high-risk gastrointestinal stromal tumor, survived during the mean follow-up period of 60 months. LWR is feasible for the management of patients with gastric submucosal tumor.

Aged↗

PubMed2005

Closing wedge osteotomy versus opening wedge osteotomy in ankylosing spondylitis with thoracolumbar kyphotic deformity.

STUDY DESIGN: Retrospective. OBJECTIVES: To compare lumbar posterior opening wedge osteotomy (OWO) and closing wedge osteotomy (CWO) in patients with thoracolumbar kyphotic deformity attributable to ankylosing spondylitis. SUMMARY OF BACKGROUND DATA: OWO and CWO have been used to correct ankylosing spondylitis-related kyphotic deformity, but the ideal surgical procedure remains controversial. METHODS: Sixty-six patients underwent OWO, and 51 underwent CWO (102 male, 15 female; mean age, 34.8 years; age range, 17-55 years). Radiographic results, complications, and patient satisfaction were analyzed over a mean follow-up of 3.6 years (range, 2.1-5.3 years) RESULTS: For OWO and CWO, mean operative times were 183 and 218 minutes, and mean blood losses were 1101 and 1915 mL, respectively. Lumbar lordosis increased by 37 degrees with OWO versus 36 degrees with CWO group, as shown on final radiographs. Sagittal imbalance improved 80 and 77 mm with OWO and CWO, respectively. Complications included delayed union in three patients and a broken rod at the osteotomy site in the OWO group. Six transient neurologic deficits occurred overall. No mortality or major complications occurred. Five patients developed junctional kyphosis (two undergoing OWO, three undergoing CWO), and all required repeat operation. Satisfactory clinical outcomes were achieved in both groups. CONCLUSION: Both OWO and CWO were safe and enabled substantial correction, with good clinical results. CWO resulted in a significantly longer operative time and more bleeding but offered fewer instances of paralytic ileus or delayed union with a broken rod.

Adolescent↗