Clinical outcomes after increasing bladder outlet resistance without augmentation cystoplasty in neurogenic bladder.

INTRODUCTION: Patients with neurogenic bladder (NGB) and urinary incontinence (UI) due to low bladder outlet resistance may require bladder neck procedures (BNPs) to achieve continence. These patients may also have reduced bladder capacity and or elevated detrusor storage pressures that require augmentation cystoplasty (AC). AC is not without complications that include risks for bladder rupture, urolithiasis, urinary tract infections and metabolic issues. Avoidance of AC would be helpful in patients with neurogenic urinary incontinence that have safe bladder parameters in the setting of low bladder outlet resistance. OBJECTIVE: To determine if pre-operative urodynamics could select children with NGBs and UI for isolated BNPs without AC. Additionally we sought to determine the safety of BNPs without AC and future need of AC with long-term follow-up. STUDY DESIGN: This is an IRB-approved retrospective analysis of all patients undergoing BNPs for management of neurogenic UI over a 17-year period. We separated these BNP patients into two groups: No AC + BNP (Group 1) vs. AC + BNP (Group 2). Our primary analyses focused on postoperative outcomes for patients in Group 1. Outcomes assessed included additional surgical procedures, urodynamic changes, development of CKD, new hydronephrosis (HDN) and vesicoureteral reflux (VUR). Secondary analysis included the timeline for the development of any bladder deterioration that necessitated AC in Group 1. RESULTS: 93 patients underwent BNP at a mean age of 10.8 years. Thirty did not have AC at the time of surgery (Group 1). These children had larger (p < 0.001) and more compliant (p < 0.001) bladders than Group 2 having simultaneous augmentation. At 6 years mean follow-up in Group 1 patients, three developed new reflux and three had new hydronephrosis. Nine (30%) had additional continence procedures. Twelve required (40%) AC at a mean of 23 months after the initial BNP. No patients had AC after 5 years. Detrusor end filling pressure increased 14.8 cm H2O (p = 0.028) and expected bladder capacity decreased 26.1% (p = 0.005) after isolated BNP. DISCUSSION: We found that from our cohort of patients who had normal bladder compliance and normal/near normal expected capacity preoperatively 40% required subsequent AC. We were unable to find pre-operative clinical parameters which predicted failure or conversion to AC. We found that 43.3% of our BNP without AC patients had no subsequent invasive procedures with mean 6-year follow-up. We found that none of our patients developed any degree of CKD. Finally, we found that the majority of patients that converted to AC after their BNP did so within the first 2 years after their initial BNP and no patients required augmentation 5 years post their initial BNP. This data validates that these patients require very strict follow up, particularly in the first 5 years after surgery. CONCLUSIONS: BNP without AC is safe in only a few selected patients with NGB. Despite preoperative selection, there are significant changes in bladder dynamics and 40% required subsequent augmentation. Bladder deterioration occurs early and generally in the first 2 years. Since there are no apparent reliable pre-operative variables predicting the need for subsequent AC, parents should be counseled regarding vigilant post-operative follow-up.

Thinking about the past to shape the present: neural activation during the recall of relationship episodes.

Reflecting on oneself and others in relationships is an ability that is central to our social existence. Specifically, considering formative autobiographical experiences in relationships may contribute to more flexibility in perceiving, as well as in shaping present relationships. Reflecting on such experiences mobilizes different social cognitive and affective processes. We aim to explore the neural basis of these processes. With a newly developed functional magnetic imaging (fMRI) task, we investigated brain activation in 35 healthy individuals during recall of relationship episodes involving themselves or others. We found that recalling formative episodes involving themselves modulated brain activity in the right parahippocampus, left precuneus, bilateral fusiform gyrus, bilateral insula, and left presupplementary motor area. These areas are involved in memory processes, self-generated thought, and affective experience. The recall of relationship episodes involving others led to similar activation patterns. Our results underscore the close link between self-reflection, understanding others, and memory processes and emphasize the role of affective dimensions for self-relevant experiences. They contribute to a growing body of research on neural mechanisms involved in complex social cognitive processes decisive for our capacity to navigate our social environment.

Seasonal plasticity in photoprotection modulates UV-induced hsp gene expression in copepods from a clear lake.

Zooplankton from clear alpine lakes is exposed to stressful levels of solar UV radiation (UVR). As these pelagic organisms experience high UVR and large changes in solar radiation conditions between ice-free and ice-cover periods, they have evolved various strategies to minimize UVR exposure and damage. Here, we studied the relation between photoprotection levels (mycosporine-like amino acids, carotenoids), antioxidant capacities, and gene expression of heat shock proteins (hsps) as indicator of stress in the copepod Cyclops abyssorum tatricus during the course of a year. Expression of hsp60, hsp70, and hsp90 was measured in the field (baseline expression [BE]) and after UVR exposure in the laboratory. The BE differed among genes and seasons (hsp60: high during summer, hsp70 and hsp90: high during the ice-cover period). The gene expression of hsp70 was upregulated after exposure to UVR (up to 5.2-fold change), while hsp60 and hsp90 were only constitutively expressed. A strong seasonal pattern was found in the photoprotective compounds and antioxidant capacities, with highest levels during the ice-free period. The extent of upregulation of hsp70 gene expression increased with decreasing photoprotection levels and peaked 24 h post UVR exposure (9.6-fold change) at the time of lowest photoprotection (February). Our data suggest that hsp70 gene expression is modulated by seasonal plasticity in photoprotection. This ability of adequate stress response is essential for survival in highly variable ecosystems such as alpine lakes.

[Effect of various compositions of riboflavin eye drops on the intraoperative corneal thickness during UVA-cross-linking in keratoconus eyes]. / Entwicklung der Hornhautdicke während der UV-Vernetzungstherapie unter Anwendung verschiedener Kompositionen von Riboflavin-Augentropfen.

BACKGROUND: During the UVA-cross-linking treatment in keratoconus patients, the UVA rays are partially absorbed in the stroma of the riboflavin-loaded cornea. This effect protects the corneal endothelium from UVA irradiation damage. The intensity of UVA light reaching the endothelium is inversely correlated with corneal thickness. The common composition of riboflavin eye drops may lead to a marked reduction in corneal thickness increasing the risk of endothelial damage. PATIENTS AND METHODS: In a retrospective analysis of 23 UVA-cross-linking procedures on 23 patients we collected data about the pre-, intra- and postoperative corneal thickness (measured with ultrasound). Among these patients and depending on the preoperative state, 8 eyes received Medio Cross (TM) eye drops (group 1), 8 eyes received Medio Cross (TM) eye drops combined with riboflavin 0.1 %/methylhydroxypropylcellulose 1,5 %/NaCl 1.1 % (group 2) and 7 eyes received riboflavin 0.2 %/methylhydroxypropylcellulose 0.5 %/NaCl 0.7 % eye drops (group 3) before and during UVA irradiation. Data are presented as means ± standard deviation. A comparison of the data was performed using (one-way) ANOVA. RESULTS: The mean corneal thickness at the end of the UVA cross-linking procedure was 67 ± 9 % (means ± standard deviation) of preoperative thickness in group 1, 118 ± 14 % in group 2 and 140 ± 23 % in group 3. The values in groups 2 and 3 were significantly different from those in the reference group 1. CONCLUSIONS: Our results show a strong variability of the postoperative corneal thickness using different standard compositions of riboflavin eye drops. Further studies are needed to find a composition of riboflavin eye drops ensuring a moderate increase in intraoperative corneal thickness to protect the corneal endothelium.

[Long-term follow-up 10 years after transpupillary thermotherapy (TTT) for small, posterior located malignant melanomas of the choroid]. / Langzeitverlauf 10 Jahre nach transpupillarer Thermotherapie (TTT) kleiner, posteriorer maligner Aderhautmelanome.

BACKGROUND: The aim of this study was to evaluate the long-term results of transpupillary thermotherapy (TTT) for small malignant choroidal melanomas. PATIENTS AND METHODS: In the time period 1/1998 to 10/1999 in a prospective non-randomised analysis 26 eyes with small malignant melanomas (located posterior to the equator with base ≤ 12 and thickness ≤ 4.5 mm) were primary treated with the TTT standard protocol (follow-up over a time span of at least 10 years). RESULTS: Thirteen women and thirteen men (mean age: 64 years) underwent TTT. The mean preoperative tumour thickness was 2.45 mm (0.8 - 4.5 mm). Ten years postoperatively tumour regression without recurrence after 1.4 treatment sessions (mean) was achieved in 16 / 26 eyes, primary regression followed by tumour regrowth in 6 / 26 eyes, and primary failure of tumour regression in 4 / 26 eyes. Two patients died on liver metastasis. Ocular complications (with preference in posterior tumours after multiple TTT sessions) were observed in 14 eyes: macular pucker in 8, macular oedema in 6, choroidal neovascularisation in 4 and posterior synechia with iris atrophy in one eye. CONCLUSIONS: Choroidal melanomas treated with TTT as a stand-alone procedure need a close monitoring since these tumours developed a significant rate of local recurrences and ocular side-effects in the long run.

Pars plana vitrectomy for visually disturbing vitreous floaters in pseudophacic eyes.

BACKGROUND: The aim of this study was to evaluate the role of vitrectomy in patients with visually disturbing vitreous opacities. PATIENTS AND METHODS: A retrospective analysis of the patient characteristics and the outcome of all pseudophacic eyes, which consecutively received in the decade 1996 to 2005 20 G pars plana vitrectomy for visually disturbing floaters, was carried out at the Mainz University Eye Clinic. RESULTS: Forty-one eyes of 32 patients (63 % university graduates, median age: 64 years) were included in the study. The mean axial length of the globe was 25.3 mm (range: 22.8 to 28.9 mm). Additional pathologies having influence on the vitreous condition were history of laser or cryo retinopexy (12 ×), buckle surgery (5 ×), complicated cataract surgery (16 ×) and Nd:YAG laser capsulotomy (4 ×). Vitreous floaters were considered to be the result of posterior vitreous detachment alone in 61 %, of asteroid hyalosis accompanied by posterior vitreous detachment in 17 %, and vitreous syneresis in 15 % of the eyes. Intraoperatively retinopexy with endolaser or cryo was performed in 6 % of cases. A secondary retinal detachment occurred in one eye (2 %). Thirty-one of 32 patients reported to be very satisfied with the postoperative result. Objectively, their visual acuity was better than or equal to preoperative acuity in 95 % of the eyes. CONCLUSION: Pars plana vitrectomy provides a highly effective treatment for visually disturbing vitreous floaters. In an era in which the expectations and demands of individuals on the quality of vision and life have increased significantly, with careful case selection the benefits of the surgical intervention may outweigh the surgical risks.

The effect of long-term storage on the biological and histological properties of cryopreserved amniotic membrane.

PURPOSE: Cryopreserved amniotic membrane (AM) is widely used in ophthalmology because of its anti-angiogenic, anti-inflammatory, and wound healing promoting capabilities. A common method to conserve the tissue is the storage in cryo-medium containing 50% glycerol at -80°C. The aim of this study was to examine the influence of storage time on the sterility as well as the histological and biological properties of cryopreserved AM. METHODS: Amniotic membrane from different donors was stored in cell culture media containing 50% glycerol for different time periods, on average 4 months (group 1), 15 months (group 2), and 24 months (group 3), at -80°C. Samples of the tissue and cryo-medium were examined for bacterial and fungal contamination. Tissue samples were incubated in 0.5 ml/cm(2) serum-free medium at 37°C. The medium was changed after 1, 2, and 3 days. The proteins released by AM were TCA-precipitated and the presence of the proteins TIMP-1 and IL-1ra was analyzed using Western blotting and semi quantified by means of image analysis. Integrity of the amniotic epithelium and the basement membrane components collagen IV, collagen VII, laminin, laminin 5, and fibronectin were examined by haematoxylin eosin stain and immunohistochemistry in cryosections of AM. RESULTS: None of the examined samples showed bacterial or fungal contamination. The soluble proteins TIMP-1 and IL-1ra were found in all samples of medium incubated for all time periods. The examined proteins were detectable after one-day incubation but the staining signal diminished significantly in the second and third wash after 48 hr and 72 hr. Differences in the intensity of the Western blot signal between the three particular groups were statistically not significant. The epithelia of all samples were intact. The basement membranes of all samples showed a similar distribution of collagen IV, collagen VII, laminin, laminin 5, and fibronectin. CONCLUSIONS: Long-term storage of amniotic membrane in cell culture media with 50% glycerol does not significantly impair sterility, histology, or biological properties of AM.

["Ghost peak" in gas chromatography in a delirious woman with severe metabolic acidosis. Intoxication with an unknown substance?]. / "Geisterpeak" in der Gas-Chromatografie bei schwerer metabolischer Azidose. Intoxikation mit unbekannter Substanz?

HISTORY AND CLINICAL FINDINGS: A 31-year-old female with known type 1 diabetes mellitus was referred because of symptomatic hyperglycemia. On admission she was delirious and impressed with marked Kussmaul breathing. All other vital signs were normal. INVESTIGATIONS: Blood serum glucose concentration was 26.4 mmol/l. Arterial blood gas analysis revealed massive metabolic acidosis (pH 6.80) with an elevated anion gap (21 mmol/l) and a marginally increased osmolar gap (21,5 mOsm/l). TREATMENT AND COURSE: Despite normalization of the serum glucose and acidemia after administration of normal saline, insulin and bicarbonate, the delirium persisted, and the possibility of an additional intoxication had to be considered. Serum headspace analysis for intoxication with solvents (gas chromatography) finally detected a "ghost peak", which could not be assigned to any established substance. The same peak was, however, found in a healthy subject's serum and was found to be a "toluene peak". Toluene is contained as "contaminator" in gels in blood collection tubes. The patient gradually regained consciousness and "merely" suffered from diabetic ketoacidosis associated with cocaine use. CONCLUSION: The differential diagnosis of high anion gap metabolic acidosis includes among other reasons intoxications with different kinds of solvents. When looking for solvents in the serum when poisoning is suspected (headspace analysis), only blood collection tubes without gel (EDTA plasma) should be used, because all gels contain solvents (in this case toluene).

Poison hemlock (Conium maculatum L.).

One of the most poisonous species amongst higher plants is Conium maculatum. It is a very common nitrophile weed species, belonging to the Apiaceae (formerly Umbelliferae) family. It contains some piperidine alkaloids (coniine, N-methyl-coniine, conhydrine, pseudoconhydrine, gamma-coniceine), which are formed by the cyclisation of an eight-carbon chain derived from four acetate units. gamma-Coniceine is the precursor of the other hemlock alkaloids. All vegetative organs, flowers and fruits contain alkaloids. The concentrations (both absolute and relative) of the different alkaloids depend on plant varieties, on ecological conditions and on the age of the plant. The characteristic biological effects of the plants are summarised on cattle, sheep, goat, swine, rabbit, elk, birds and insects and the symptoms of the human toxicosis (some cases of poisonings) are discussed according to the literature data. The general symptoms of hemlock poisoning are effects on nervous system (stimulation followed by paralysis of motor nerve endings and CNS stimulation and later depression), vomiting, trembling, problems in movement, slow and weak later rapid pulse, rapid respiration, salivation, urination, nausea, convulsions, coma and death.

Mice transgenic for exon 1 of Huntington's disease: properties of cholinergic and dopaminergic pre-synaptic function in the striatum.

In Huntington's disease (HD), neuronal loss is most prominent in the striatum leading to emotional, cognitive and progressive motor dysfunction. The R6/2 mice, transgenic for exon 1 of the HD gene, develop a neurological phenotype with similarities to these features of HD. In striatal tissue, electrically evoked release of tritiated acetylcholine (ACh) and dopamine (DA) were compared in wild-type (WT) and R6/2 mice. In R6/2 mice, the evoked release of ACh, its M2 autoreceptor-mediated maximum inhibition and its dopamine D2 heteroreceptor-mediated maximum inhibition was diminished to 51%, 74% and 87% of controls, respectively. Also, the activities of choline acetyltransferase and of synaptosomal high-affinity choline uptake decreased progressively with age in these mice. In the DA release model, however, electrical stimulation elicited equal amounts of [3H]-DA both in WT and R6/2 mice. Moreover, high-affinity DA uptake into striatal slices was similar in WT and R6/2 mice. In order to confirm these findings in vivo, intrastriatal levels of extracellular DA were measured by intracerebral microdialysis in freely moving mice: striatal DA levels were found to be equal in WT and R6/2 mice. In conclusion, in the transgenic R6/2 mice changes occur mainly in striatal cholinergic neurones and their pre-synaptic modulation, but not in the dopaminergic afferent terminals. Whether similar events also contribute to the pathogenesis of HD in humans has to be established.

[Jugular lymph node metastasis of papillary thyroid gland carcinoma 10 years later]. / Juguläre Lymphknotenmetastase von papillärem Schilddrüsenkarzinom vor zehn Jahren. Ein Fallbericht.

We present a patient with occult papillary thyroid carcinoma, in whom a single nodal metastasis had been excised. Ten years later a nodal recurrence was diagnosed by ultrasound and fine needle aspiration cytology. The diagnosis of recurrence was erroneous, and we discuss the differential diagnostic problems, the natural course, and the adequate treatment of occult papillary microcarcinoma.

Characterization of the alpha(2)-adrenoceptor subtype, which functions as alpha(2)-autoreceptor in human neocortex.

The pharmacological properties of the alpha(2)-adrenergic receptors regulating the release of norepinephrine were investigated in human neocortex. Slices were preincubated with [(3)H]norepinephrine, superfused under blockade of transmitter reuptake, and stimulated electrically. First, the autoinhibitory circuit of [(3)H]norepinephrine release was analyzed quantitatively by estimation of the K(d) of norepinephrine at the alpha(2)-autoreceptor (10(-7.99) M), the concentration of the endogenous transmitter causing this autoinhibition at a stimulation frequency of 3 Hz (10(-7.61) M), and the maximum inhibition obtainable through the autoreceptor (83%). Second, antagonist pK(b) values of nine antagonists were determined by using their pEC(50) values (negative logarithms of antagonist concentrations that increased the electrically evoked overflow of tritium by 50%) against the release-inhibiting effect of the endogenous transmitter. When compared with binding or functional data from the literature, the pK(b) values correlated best with the antagonist affinities at alpha(2A) binding sites. In contrast, the correlations with alpha(2B), alpha(2C), and alpha(2D) sites were not as good. It is concluded that in human neocortex prejunctional autoreceptors are alpha(2A).

Plant cyanogenic glycosides.

The cyanogenic glycosides belong to the products of secondary metabolism, to the natural products of plants. These compounds are composed of an alpha-hydroxynitrile type aglycone and of a sugar moiety (mostly D-glucose). The distribution of the cyanogenic glycosides (CGs) in the plant kingdom is relatively wide, the number of CG-containing taxa is at least 2500, and a lot of such taxa belong to families Fabaceae, Rosaceae, Linaceae, Compositae and others. Different methods of determination are discussed (including the indirect classical photometrical and the new direct chromatographic ones). The genetic control of cyanogenesis has no unique mechanism, the plants show variation in the amount of the produced HCN. The production of HCN depends on both the biosynthesis of CGs and on the existence (or absence) of its degrading enzymes. The biosynthetic precursors of the CGs are different L-amino acids, these are hydroxylated then the N-hydroxylamino acids are converted to aldoximes, these are turned into nitriles. The last ones are hydroxylated to alpha-hydroxynitriles and then they are glycosilated to CGs. The generation of HCN from CGs is a two step process involving a deglycosilation and a cleavage of the molecule (regulated by beta-glucosidase and alpha-hydroxynitrilase). The tissue level compartmentalisation of CGs and their hydrolysing enzymes prevents large-scale hydrolysis in intact plant tissue. The actual level of CGs is determined by various factors both developmental and ecological ones, which are reviewed too. The last part of the present work demonstrates the biological roles of CGs in plant physiological processes and in plant defence mechanisms as well. The effect of CGs (HCN) on different animals, the symptoms of poisonings are discussed to cows, sheep, donkeys, horses and chicks. Finally, the poisonous effects of cassava (Manihot esculenta) roots are summarised on experimental animals and on the human organism.

[Congenital generalized dropsy and intrapericardial fetal teratoma. Report of a case of prenatal diagnosis]. / Anasarque foeto-placentaire et tératome intra-péricardique foetal. A propos d'un cas de diagnostic anténatal.

Intrapericardial teratomas are rare tumors usually occurring in early infancy. Such a case was diagnosed in a 20 week old fetus, with a lethal outcome. About fifteen cases of intrapericardial teratoma have been reported in the fetal period. They are usually symptomatic, with a more or less severe pericardial effusion, sometimes complicated by cardiac compression and/or hydrops fetalis. Prognosis of the prenatally diagnosed pericardial teratomas is more related to the occurrence of hydrops fetalis than to the behavior of the tumor itself. The main interest of sonographic ante-natal diagnosis consists of the possible improvement of hemodynamic consequences through in utero pericardiocentesis. Macroscopic and microscopic features of this cardiac tumor are similar to those of extrapericardial teratomas. Most tumors discovered in fetal period are mature and histologically benign lesions. Only one case showed immature components. The coexistence of a malignant component (germ cell or non germ cell tumor) has been described in the postnatal and adulthood.

Study of fossil tracks due to 50 < or = Z < or = 92 galactic cosmic ray nuclei in meteoritic crystals: results and perspectives.

A new approach to the problem of investigation of charge and energy spectra of ultra heavy Galactic cosmic ray nuclei, based on fossil track study of extraterrestrial olivine crystals has been developed. The results of an investigation of ultra heavy Galactic cosmic ray nuclei (Z=50-92) in meteoritic olivine crystals are presented. The technique was based on calibration of olivine crystals with accelerated Xe, Au, Pb and U ions and well-controlled partial annealing of "fresh" and "fossil" tracks. It allows us to determine the charge spectra and abundances of cosmic ray nuclei based on fossil track length study in meteoritic and Moon crystals. The comparative studies of the spectra of "fossil' tracks and tracks due to 208Pb and 238U nuclei have shown that the group of 210 micrometers "fossil" tracks, first observed in 1980 at JINR is due to Th-U nuclei-products of recent r-process nucleosynthesis in our Galaxy. The method in principle allows one to resolve Pt-Pb peaks in fossil tracks, to establish the upper limit of the abundance of Z>110 nuclei in the Galactic cosmic rays at the level < or = 10(-3) to the abundance of actinide nuclei and to get information on the history of Z>50 cosmic ray nuclei in time interval up to 220 M.Y.

[Ovarian metastasis of colorectal adenocarcinomas. A clinico-pathological study of 41 cases]. / Métastases ovariennes des adénocarcinomes colorectaux Etude anatomo-clinique de 41 observations.

We report a series of 41 ovarian metastases from colorectal adenocarcinomas. The patients'mean age was 57.1 years at the time the metastasis was discovered, and 55.8 years at the time the primary carcinoma was found. The diagnosis of the primary tumour was anterior to the metastasis in 25 cases (mean interval 21 months), simultaneous in 13 and posterior in 3 others. The metastases formed cystic and solid masses with a mean weight of 330 g. The endometrioid architectural type was the most frequent, either pure (71%, 29/41) or associated with a mucinous component (17%, 7/41). Pure mucinous or other architectural types were rare. The endometrioid type was characterized by glands with a garland pattern, and intraluminal dirty tumoral necrosis. Immunohistochemistry helped to distinguish the metastases of endometrioid type from serous or endometrioid primary ovarian carcinoma; 71% of the former were CK7(-)/CK20(+), and 100% of the latter had the reverse profile CK7(+)/CK20(-).

Toxins of Amanita phalloides.

The most poisonous mushroom toxins are produced by Amanita phalloides (death cap). The occurrence and chemistry of three groups of toxins (amatoxins, phallotoxins and virotoxins) are summarized. The concentration and distribution of toxins in certain species are variable, with the young fruit body containing lower, and the well-developed fungus higher concentrations, but there is a high variability among specimens collected in the same region. Regarding phallotoxins, the volva (the ring) is the most poisonous. The most important biochemical effect of amatoxins is the inhibition of RNA polymerases (especially polymerase II). This interaction leads to a tight complex and the inhibition is of a non-competitive type. Non-mammalian polymerases show little sensitivity to amanitins. The amatoxins cause necrosis of the liver, also partly in the kidney, with the cellular changes causing the fragmentation and segregation of all nuclear components. Various groups of somatic cells of emanation resistance have been isolated, including from a mutant of Drosophila melanogaster. The phallotoxins stimulate the polymerization of G-actin and stabilize the F-actin filaments. The interaction of phallotoxins occurs via the small, 15-membered ring, on the left side of the spatial formula. The symptoms of human poisoning and the changes in toxin concentrations in different organs are summarized. Conventional therapy includes: (1) stabilization of patient's condition with the correction of hypoglycaemia and electrolytes; (2) decontamination; and (3) chemotherapy with different compounds. Finally, certain antagonists and protective compounds are reviewed, bearing in mind that today these have more of a theoretical than a practical role.

Entrance skin exposure and mean glandular dose: effect of scatter and field gradient at mammography.

PURPOSE: To investigate the effect of scatter and x-ray field gradient on entrance skin exposure and mean glandular dose by using the measurement protocol of the American College of Radiology. MATERIALS AND METHODS: The exposure difference between the off-axis geometry of the American College of Radiology protocol and the central-axis geometry was measured by using eight common ionization chambers and two mammographic units (Senographe DMR; GE Medical Systems, Milwaukee, Wis; and Mam-CP II; Transcontinental X-ray, Charlotte, NC) at 25, 28, and 30 kVp. The field gradient was also measured on film with a scanning densitometer. RESULTS: The central-axis exposure was 2.0%-3.6% higher than the off-axis exposure for the Senographe DMR unit and 3.1%-8.0% higher for the Mam-CP II unit. The maximum phantom scatter was 0.7% (Senographe DMR) and 1.3% (Mam-CP II). CONCLUSION: Entrance skin exposure varies, depending on the type of ionization chamber and the characteristics of the mammographic unit. Determination of mean glandular dose with the American College of Radiology protocol may lead to underestimates of the actual measured dose by 4%-8% for the x-ray machines used in this study.