Study on the Tongue and Groove Effect of the Elekta Multileaf Collimator Using Monte Carlo Simulation and Film Dosimetry

BACKGROUND: Nowadays, multileaf collimation of the treatment fields from medical linear accelerators is a common option. Due to the design of the leaf sides, the tongue and groove effect occurs for certain multileaf collimator applications such as the abutment of fields where the beam edges are defined by the sides of the leaves. MATERIAL AND METHODS: In this study, the tongue and groove effect was measured for two pairs of irregular multileaf collimator fields that were matched along leaf sides in two steps. Measurements were made at 10 cm depth in a polystyrene phantom using Kodak EDR2 films for a photon beam energy of 6 MV on an Elekta Sli-plus accelerator. To verify the measurements, full Monte Carlo simulations were done. In the simulations, the design of the leaf sides was taken into account and one component module of BEAM code was modified to correctly simulate the Elekta multileaf collimator. RESULTS AND CONCLUSION: The results of measurements and simulations are in good agreement and within the tolerance of film dosimetry.     

Comparison of Endovenous Treatment with an 810 nm Laser versus Conventional Stripping of the Great Saphenous Vein in Patients with Primary Varicose Veins

BACKGROUND: Patients with varicose veins seek medical assistance for many reasons, including esthetic ones. The development of suitable and more flexible instruments, along with less invasive techniques, enables the establishment of new therapeutic procedures. OBJECTIVE: To compare endovenous great saphenous vein photocoagulation with an 810 nm diode laser and the conventional stripping operation in the same patient. METHODS: Twenty patients selected for operative treatment of primary great saphenous vein insufficiency on duplex scanning were assigned to a bilateral random comparison. In all cases, both techniques were performed, one on each lower limb. Clinically, evaluation was assessed on the seventh, thirtieth, and sixtieth postoperative days. Patients underwent examination with duplex ultrasonography and air plethysmography during the follow-up. RESULTS: Patients who received endovenous photocoagulation presented with the same pain but fewer swellings and less bruising than the stripping side. Most patients indicated that the limb operated on by laser received more benefits than the other. There was only one recanalization and no adverse effects. The venous filling time showed better hemodynamics in both techniques. CONCLUSION: The endovenous great saphenous vein photocoagulation is safe and well tolerated and presents results comparable to those of conventional stripping.     

Development of an in vitro burn wound model

Healing of a deeper burn wound is a complex process that often leads to scar formation. Skin wound model systems are important for the development of treatments preventing scarring. The aim of this study is to develop a standardized in vitro burn wound model that resembles the in vivo situation. A burn wound (10 × 2 mm) was made in ex vivo skin and the skin samples were cultured at the air–liquid interface for 7, 14, and 21 days. Cells in the skin biopsies maintained their viability during the 21-day culture period. During culture, reepithelialization of the wound took place from the surrounding tissue and fibroblasts migrated into the wound area. Cells of the epithelial tongue and fibroblasts near the wound margin were proliferating. During culture, skin-derived antileukoproteinase and keratin 17 were expressed only in the epithelial tongue. Both collagen type IV and laminin were present underneath the newly formed epidermis, indicating that the basement membrane was restored. These results show that the burn wound model has many similarities to in vivo wound healing. This burn wound model may be useful to study different aspects of wound healing and testing pharmaceuticals and cosmetics on, e.g., migration and reepithelialization.     

The dilemma of Jehovah's Witness children who need blood to survive

Summary Medical researchers must continue to develop and test non-blood oxygen-transport products. Resources provided by the Jehovah's Witness Hospital Assistance Line must be consulted. Sickle cell researchers must continue to test non-blood treatment. Information about non-blood treatments must be disbursed. Ways to enhance parental comport as the laws further and further support children's best interest must be provided. Information regarding cultural diversity must be disseminated. Hospitals and healthcare agencies that have not done so must institute the use of ethics consulting or ethics committees. Nurse ethicists must continue development of the role of educating staff; mediation, arbitration and negotiation; problem solving; obtaining legal opinion; providing patient, family, or staff advocacy; and helping to reduce suffering on the part of the providers. Difficult ethical decisions should continue to be debated.Were the staff at X Med Center correct in overriding parental wishes and breaking tenets of their faith? In the doctor's, nurse's lawyer's, and judge's view they were. The child, now eight years old, is alive and well. The stroke resolved, and imminent death averted. The parents' and child's views are not presently available. Whether the family is suffering from the child's loss of his relationship with God, or are secretly relieved in their hearts that they are not, like Rita Swan, mourning their dead son, is unknown. What is known, is that this was a difficult case for all involved, and that such cases will continue to present themselves in the future.     

Cardiac damage induced by 2-amino-3-methyl-imidazo[4,5-f]quinoline in nonhuman primates.

The heterocyclic aromatic amine 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) is a potent hepatocarcinogen in cynomolgus and rhesus monkeys. The finding of high cardiac IQ-DNA adduct levels prompted a histopathological study of perfusion-fixed hearts from 10 tumor-bearing monkeys chronically dosed with IQ at 10 mg/kg or 20 mg/kg 5 days per week for 48-80 months. Two monkeys dosed only with the vehicle for IQ, hydroxypropylcellulose, served as controls. All the monkeys had normal heart weights, and no abnormalities were observed upon gross inspection of the hearts. Microscopically, focal myocardial lesions were observed in 8 of 10 monkeys dosed with IQ. Light microscopic abnormalities included myocyte necrosis with or without chronic inflammatory infiltrates, interstitial fibrosis with myocyte hypertrophy or atrophy, and vasculitis. Electron microscopic findings included disruption of the mitochondrial architecture (i.e., mitochondrial swelling and clearing of matrix densities), myofibrillar loss, disorganization of the normal alignment of sarcomeres, and occasional myocytes showing nuclear hypertrophy or peripheral clumping of the nuclear chromatin. There was some correlation between the cumulative dose of IQ and the extent of the myocardial abnormalities. These findings suggest that chronic exposure to IQ can lead to myocardial damage in monkeys. Although focal and not associated with clinical evidence of heart failure, these abnormalities may represent the initial stages of IQ-induced toxic cardiomyopathy.     

Clastogenic effect of fenfluramine in mice bone marrow cells in vivo

Fenfluramine, an amphetamine derivative used in the treatment of obesity, has been evaluated in vivo in the bone marrow cells of Swiss albino mice using two cytogenetic endpoints for assessing its genotoxic and clastogenic potentials. Concentrations of 0.75, 1.5, 3.0, and 5.0 mg/kg b.w. were administered orally for the study of sister chromatid exchange frequencies and chromosome aberrations (CA). SCE frequencies showed a positive dose response; 1.5 mg/kg being the minimum effective concentration. Fen caused a prolongation of cell cycle at all concentrations. Except for the minimum therapeutic dose (0.75 mg), all other doses (1.5, 3.0, and 5.0 mg) showed a significant increase in the percentage of damaged cells over that of the vehicle control. The degree of clastogenicity was directly proportional to the dosage used and inversely related with the duration of treatment. A gradual reduction of the clastogenic potential was observed after 12 and 24 hr of exposure, indicating that the maximum effect occurs at the middle or late synthetic phase of the cell cycle. This study, probably the first detailed screening of the drug for its genotoxicity, shows that Fen is moderately clastogenic and a DNA damaging agent in vivo.