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Grenz Rays
Grenz rays are part of the electromagnetic spectrum comprising low energy (ultrasoft) X-rays. These were first investigated by Gustav Bucky in 1923 using a cathode vacuum tube with a lithium borate glass window, which he labeled Grenz rays as he believed that the biological effects resembled those of UV light and traditional X-rays and hence were on the border between the two (''Grenz'' = border in German). These rays are also known as Bucky rays.Lewis H: Grenz ray therapy: Regimens & Results.Chapter 15 in Physical Modalities in Dermatologic Therapy. Goldschmidt H (ed.) 1978 Springer-Verlag Grenz rays are produced by specially calibrated X-ray machines generally operating in the 10 to 30 kV range to produce X-rays with HVL less than 0.035 mm in aluminum.Hollander MB : Grenz rays. Journal of Investigative Dermatology 21,15–26 July 1953. (HVL is half-value layer, and refers to a thickness of a given material that will cut the X-ray flux by 50%). Grenz rays are absorbed b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-rays
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz ( to ) and energies in the range 145 eV to 124 keV. X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. In many languages, X-radiation is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it on November 8, 1895. He named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . Spellings of ''X-ray(s)'' in English include the variants ''x-ray(s)'', ''xray(s)'', and ''X ray(s)''. The most familiar use of X-rays is checking for fractures (broken bones), but X-rays are also used in other ways. F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gustav Peter Bucky
Gustav Peter Bucky (September 3, 1880Several sources list an 1899 birthdate, but this would mean that Bucky was in his early teens when he introduced the Bucky diaphragm. - February 19, 1963) was a German-American radiologist who made early contributions to X-ray technique. The Bucky diaphragm and the subsequent Bucky-Potter grid, devices that prevent scattered X-ray particles from reaching the X-ray film, are named for him. Bucky spent significant portions of his career in both Germany and the United States. He was close friends with Albert Einstein and shared a patent with him for a self-adjusting camera. Early life and career Bucky was born in Leipzig. He wanted to become an engineer, but his parents steered him toward medical school. He studied medicine in Geneva and Leipzig, graduating from medical school in 1906 after completing a thesis on the mechanisms of the movement of paratyphus from lymph and blood vessels to the gastrointestinal tract. Since the mid-1890s, physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-value Layer
material's half-value layer (HVL), or half-value thickness, is the thickness of the material at which the intensity of radiation entering it is reduced by one half. HVL can also be expressed in terms of air kerma rate (AKR), rather than intensity: the half-value layer is the thickness of specified material that, "attenuates the beam of radiation to an extent such that the AKR is reduced to one-half of its original value. In this definition the contribution of all scattered radiation, other than any ..present initially in the beam concerned, is deemed to be excluded." Rather than AKR, measurements of air kerma, exposure, or exposure rate can be used to determine half value layer, as long as it is given in the description. Half-value layer refers to the first half-value layer, where subsequent (i.e. second) half-value layers refer to the amount of specified material that will reduce the air kerma rate by one-half after material has been inserted into the beam that is equal to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langerhans Cell
A Langerhans cell (LC) is a tissue-resident macrophage of the skin. These cells contain organelles called Birbeck granules. They are present in all layers of the epidermis and are most prominent in the stratum spinosum. They also occur in the papillary dermis, particularly around blood vessels, as well as in the mucosa of the mouth, foreskin, and vaginal epithelium. They can be found in other tissues, such as lymph nodes, particularly in association with the condition Langerhans cell histiocytosis (LCH). Function In skin infections, the local Langerhans cells take up and process microbial antigens to become fully functional antigen-presenting cells. Generally, tissue-resident macrophages are involved in immune homeostasis and the uptake of apoptotic bodies. However, Langerhans cells can also take on a dendritic cell-like phenotype and migrate to lymph nodes to interact with naive T-cells. Langerhans cells derive from primitive erythro-myeloid progenitors that arise in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eczema
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can vary from small to covering the entire body. Dermatitis is often called eczema, and the difference between those terms is not standardized. The exact cause of the condition is often unclear. Cases may involve a combination of allergy and poor venous return. The type of dermatitis is generally determined by the person's history and the location of the rash. For example, irritant dermatitis often occurs on the hands of those who frequently get them wet. Allergic contact dermatitis occurs upon exposure to an allergen, causing a hypersensitivity reaction in the skin. Prevention of atopic dermatitis is typically with essential fatty acids, and may be treated with moisturizers and steroid creams. The steroid creams should generally be of m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psoriasis
Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete body coverage. Injury to the skin can trigger psoriatic skin changes at that spot, which is known as the Koebner phenomenon. The five main types of psoriasis are plaque, guttate, inverse, pustular, and erythrodermic. Plaque psoriasis, also known as psoriasis vulgaris, makes up about 90% of cases. It typically presents as red patches with white scales on top. Areas of the body most commonly affected are the back of the forearms, shins, navel area, and scalp. Guttate psoriasis has drop-shaped lesions. Pustular psoriasis presents as small, noninfectious, pus-filled blisters. Inverse psoriasis forms red patches in skin folds. Erythrodermic psoriasis occurs when the rash becomes very widespread, and can develop from any of the other types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pruritus Ani
Pruritus ani is the irritation of the skin at the exit of the rectum, known as the anus, causing the desire to scratch. The intensity of anal itching increases from moisture, pressure, and rubbing caused by clothing and sitting. At worst, anal itching causes intolerable discomfort that often is accompanied by burning and soreness. It is estimated that up to 5% of the population of the United States experiences this type of discomfort daily. Causes If a specific cause for pruritus ani is found it is classified as "secondary pruritus ani". If a specific cause is ''not'' found it is classified as "idiopathic pruritus ani". The irritation can be caused by intestinal parasites, anal perspiration, frequent liquid stools, diarrhea, residual stool deposits, or the escape of small amounts of stool as a result of incontinence or flatulence. Another cause is yeast infection or candidiasis. Some diseases increase the possibility of yeast infections, such as diabetes mellitus or HIV inf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pruritus Vulvae
Pruritus vulvae is itchiness of the vulva, which is the counterpart of pruritus scroti, and may have many different causes. Patch testing may be used to diagnose the cause. Causes This condition is a symptom of an underlying condition more often than it is a primary condition. Vulva irritation can be caused by any moisture left on the skin. This moisture may be perspiration, urine, vaginal discharge or small amounts of stool. It may be caused by vaginal infections, vulvitis, HPV (human papilloma virus) infection, anal incontinence, Bowen's disease Squamous-cell skin cancer, also known as cutaneous squamous-cell carcinoma (cSCC), is one of the main types of skin cancer along with basal cell cancer and melanoma. It usually presents as a hard lump with a scaly top but can also form an ulcer. O ..., or dietary irritants (caffeine, potatoes, chilli, capsicum, tomatoes, and peanuts). Treatment with antibiotics can lead to a yeast infection and irritation of the vulva. Some dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hailey–Hailey Disease
Hailey–Hailey disease, or familial benign chronic pemphigus or familial benign pemphigus, was originally described by the Hailey brothers (Hugh Edward and William Howard) in 1939. It is a genetic disorder that causes blisters to form on the skin. Signs and symptoms HHD is characterized by outbreaks of rashes and blisters on the skin. Affected areas of skin undergo repeated blistering and inflammation, and may be painful to the touch. Areas where the skin folds, as well as the armpits, groin, neck, buttocks and under the breasts are most commonly affected. In addition to blistering, other symptoms which accompany HHD include acantholysis, erythema and hyperkeratosis. Causes The cause of the disease is a haploinsufficiency of the enzyme ATP2C1; the ATP2C1 gene is located on chromosome 3, which encodes the protein hSPCA1. A mutation on one copy of the gene causes only half of this necessary protein to be made and the cells of the skin do not adhere together properly due to malfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinic Keratosis
Actinic keratosis (AK), sometimes called solar keratosis or senile keratosis, is a pre-cancerous area of thick, scaly, or crusty skin.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. . Actinic keratosis is a disorder (''-osis'') of epidermal keratinocytes that is induced by ultraviolet (UV) light exposure ('' actin-''). These growths are more common in fair-skinned people and those who are frequently in the sun. They are believed to form when skin gets damaged by UV radiation from the sun or indoor tanning beds, usually over the course of decades. Given their pre-cancerous nature, if left untreated, they may turn into a type of skin cancer called squamous cell carcinoma. Untreated lesions have up to a 20% risk of progression to squamous cell carcinoma, so treatment by a dermatologist is recommended. Actinic keratoses characteristically appear as thick, scaly, or crusty areas that often feel dry or rough. Size commonly ranges be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bowen's Disease
Squamous-cell skin cancer, also known as cutaneous squamous-cell carcinoma (cSCC), is one of the main types of skin cancer along with basal cell cancer and melanoma. It usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months. Squamous-cell skin cancer is more likely to spread to distant areas than basal cell cancer. When confined to the outermost layer of the skin, a precancerous or ''in situ'' form of cSCC is known as Bowen's disease. The greatest risk factor is high total exposure to ultraviolet radiation from the sun. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen's disease, arsenic exposure, radiation therapy, tobacco smoking, poor immune system function, previous basal cell carcinoma, and HPV infection. Risk from UV radiation is related to total exposure, rather than early exposure. Tanning beds are becoming another common source of ultraviolet radiation. Risk is also elevated in ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatitis
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can vary from small to covering the entire body. Dermatitis is often called eczema, and the difference between those terms is not standardized. The exact cause of the condition is often unclear. Cases may involve a combination of allergy and poor venous return. The type of dermatitis is generally determined by the person's history and the location of the rash. For example, irritant dermatitis often occurs on the hands of those who frequently get them wet. Allergic contact dermatitis occurs upon exposure to an allergen, causing a hypersensitivity reaction in the skin. Prevention of atopic dermatitis is typically with essential fatty acids, and may be treated with moisturizers and steroid creams. The steroid creams should generally be o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
