Exploratory survey of initial image quality in new digital mammography units prior to use in patients in Mexico.

In Mexico, previous studies performed to evaluate the image quality in 2D digital mammography facilities show a poor image quality that is not compatible with mammography screening that may modify breast cancer mortality rate. Image quality is lost due to the quality assurance programs are not implemented. We carried out an exploratory survey of thirty-six new (FFDM) units from a single manufacturer installed in several cities of the Mexican Republic with two types of target/filter combination (Mo/Mo and W/Rh). Tests were performed according to NOM-041-SSA1-2011 (Mexico), the regulation indicates that all facilities using digital mammography systems must maintain a QC program equal to the QC program recommended by the manufacturer. However, QC program recommended by the manufacturer meets with FDA and ACR Regulations. Digital mammography units evaluated exceeds quality image standards established by the ACR and FDA, even though, the W/Rh combination achieved a higher performance and reduces the average glandular dose. All mammography units met the quality control standards established by ACR, FDA and Mexican regulations. Then, the objective of this study was to evaluate the initial image quality and compliances with the manufacturer's quality control specifications before use it in patients in new full-field 2D digital mammography (FFDM) units and compares average glandular dose (AGD) with FFDM units using different anode/filter combinations (Mo/Mo and W/Rh).

Thermoluminescent characteristics of LiF:Mg, Cu, P and CaSO4:Dy for low dose measurement.

Thermoluminescence (TL) characteristics for LiF:Mg, Cu, P, and CaSO4:Dy under the homogeneous field of X-ray beams of diagnostic irradiation and its verification using thermoluminescence dosimetry are presented. The irradiation were performed utilizing a conventional X-ray equipment installed at the Hospital Juárez Norte of México. Different thermoluminescence characteristics of two material were studied, such as batch homogeneity, glow curve, linearity, detection threshold, reproducibility, relative sensitivity and fading. Materials were calibrated in terms of absorbed dose to the standard calibration distance and they were positioned in a generic phantom. The dose analysis, verification and comparison with the measurements obtained by the TLD-100 were performed. Results indicate that the dosimetric peak appears at 202°C and 277.5°C for LiF:Mg, Cu, P and CaSO4:Dy, respectively. TL response as a function of X-ray dose showed a linearity behavior in the very low dose range for all materials. However, the TLD-100 is not accurate for measurements below 4mGy. CaSO4:Dy is 80% more sensitive than TLD-100 and it show the lowest detection threshold, whereas LiF:Mg, Cu, P is 60% more sensitive than TLD-100. All materials showed very good repeatability. Fading for a period of one month at room temperature showed low fading LiF:Mg, Cu, P, medium and high for TLD-100 and CaSO4:Dy. The results suggest that CaSO4:Dy and LiF:Mg, Cu, P are suitable for measurements at low doses used in radiodiagnostic.

Thermoluminescent dosimeters for low dose X-ray measurements.

The response of TLD-100, CaSO4:Dy and LiF:Mg,Cu,P for a range of X-ray low dose was measured. For calibration, the TLDs were arranged at the center of the X-ray field. The dose output of the X-ray machine was determined using an ACCU-Gold. All dosimeters were exposed at the available air kerma values of 14.69 mGy within a field 10×10 cm(2) at 80 cm of SSD. Results of LiF:Mg,Cu,P X-ray irradiated showed 4.8 times higher sensitivity than TLD-100. Meanwhile, TL response of CaSO4:Dy exposed at the same dose was 5.6 time higher than TLD-100. Experimental results show for low dose X-ray measurements a better linearity for LiF:Mg,Cu,P compared with that of TLD-100. CaSO4:Dy showed a linearity from 0.1 to 60 mGy.

Exploratory survey of image quality on CR digital mammography imaging systems in Mexico.

The purpose of this study was to assess the current status of image quality and dose in computed radiographic digital mammography (CRDM) systems. Studies included CRDM systems of various models and manufacturers which dose and image quality comparisons were performed. Due to the recent rise in the use of digital radiographic systems in Mexico, CRDM systems are rapidly replacing conventional film-screen systems without any regard to quality control or image quality standards. Study was conducted in 65 mammography facilities which use CRDM systems in the Mexico City and surrounding States. The systems were tested as used clinically. This means that the dose and beam qualities were selected using the automatic beam selection and photo-timed features. All systems surveyed generate laser film hardcopies for the radiologist to read on a scope or mammographic high luminance light box. It was found that 51 of CRDM systems presented a variety of image artefacts and non-uniformities arising from inadequate acquisition and processing, as well as from the laser printer itself. Undisciplined alteration of image processing settings by the technologist was found to be a serious prevalent problem in 42 facilities. Only four of them showed an image QC program which is periodically monitored by a medical physicist. The Average Glandular Dose (AGD) in the surveyed systems was estimated to have a mean value of 2.4 mGy. To improve image quality in mammography and make more efficient screening mammographic in early detection of breast cancer is required new legislation.

Radiation dose reduction in a neonatal intensive care unit in computed radiography.

The purpose of this study was to evaluate the dose received by chest x-rays in neonatal care with thermoluminescent dosimetry and to determine the level of exposure where the quantum noise level does not affect the diagnostic image quality in order to reduce the dose to neonates. In pediatric radiology, especially the prematurely born children are highly sensitive to the radiation because of the highly mitotic state of their cells; in general, the sensitivity of a tissue to radiation is directly proportional to its rate of proliferation. The sample consisted of 208 neonatal chest x-rays of 12 neonates admitted and treated in a Neonatal Intensive Care Unit (NICU). All the neonates were preterm in the range of 28-34 weeks, with a mean of 30.8 weeks. Entrance Surface Doses (ESD) values for chest x-rays are higher than the DRL of 50 µGy proposed by the National Radiological Protection Board (NRPB). In order to reduce the dose to neonates, the optimum image quality was achieved by determining the level of ESD where level noise does not affect the diagnostic image quality. The optimum ESD was estimated for additional 20 chest x-rays increasing kVp and reducing mAs until quantum noise affects image quality.

Thermoluminescence of zirconium oxide nanostructured to mammography X-ray beams.

In the present work thermoluminescent (TL) response of zirconium oxide (ZrO2) nanostructured induced by mammography X-ray radiation was investigated. Measurements were made of the response per unit air kerma of ZrO2 with mammography equipment parameters (semiautomatic exposure control, 24 kVp and 108 mAs). The calibration curves were obtained by simultaneously irradiating ZrO2 samples and ion chamber. Samples of ZrO2 showed a linear response as a function of entrance skin air kerma. The observed results in TL properties suggest that ZrO2 nanostructured could be considered as an effective material for X-ray beams dosimetry if appropriate calibration procedures are performed.

[Anemia in chronic lymphatic leukemia: is erythropoietin the solution?]. / La anemia en la leucemia linfática crónica: Es la eritropoyetina la solución del problema?

Anemia is a common complication in the clinical course of chronic lymphocytic leukemia. Low hemoglobin levels both correlate with an adverse prognosis and adversely affect the quality of life of chronic lymphocytic leukemia patients. Different physiopathological phenomena may lead to anemia: marrow infiltration, hypersplenism, immune hemolysis or toxicity of chemotherapy. Treatment with human recombinant erythropoietic agents has been shown to be effective for anemia associated with different lymphoproliferative syndromes. This paper analyses the available evidence on erythropoietic agent treatment for chronic lymphocytic leukemia associated anemia. The comparative effect of different dosage schemes, the role of possible response-prediction factors such as the endogenous erythropoietin level and the results achieved using darbopoietin alpha are reviewed.

[Antiplatelets and anticoagulants in acute coronary syndromes: levels of evidence]. / Antiagregación y anticoagulación en síndromes coronarios agudos: niveles de evidencia.

Management of acute coronary syndromes (ACS) has moved rapidly in parallel with our understanding of the pathophysiological basis of the disease. In the eighties, the demonstration of the pivotal role of coronary thrombosis in the etiology of a ACS led to administration of aspirin and unfractionated heparin. In recent years, new medical and invasive therapies have been developed: anti-platelets (thienopyridines and glycoprotein Ilb/IlIa inhibitors), antithrombins (low molecularweight heparins) and most recently, factor Xa inhibitors (pentasaccharides). As new treatments are rapidly added, clinicians are constantly challenged to incorporate new information and guidelines into their practices in a timely fashion.

[Diagnosis and management of deep venous thrombosis]. / Diagnóstico y tratamiento de la trombosis venosa profunda.

Deep-vein thrombosis (DVT) is a common condition that can lead to complications such as postphlebitic syndrome, pulmonary embolism and death. Currently, an algorithm strategy combining pretest probability, D-dimer testing and compression ultrasonography imaging allows for safe and convenient estimation of suspected lower-limb thrombosis. The mainstay of treatment is anticoagulation therapy. The use of low-molecular-weight heparin or pentasaccharide (fondaparinux) allows for outpatient management of most patients with DVT. The duration of anticoagulation depends on whether the primary event was idiopathic or secondary to a transient risk factor. Interventions such as thrombolysis and placement of inferior vena cava filter are reserved for special situations.

[Breakage and embolization of an epicutaneous central catheter with migration ot the right lobar pulmonary artery]. / Rotura y embolización de catéter central epicutáneo con emigración a la arteria pulmonar lobar derecha.

A neonate with meningitis required placement of several catheters for treatment. One catheter broke and a fragment embolized in the lobar branch of a pulmonary artery. This critical situation produced no symptoms and was successfully managed by percutaneous extraction from the femoral artery. Percutaneous central catheters made of silicon are used increasingly for long-term treatment of critically ill neonates. Such catheters are highly useful and effective but are not free of complications that can be serious or even fatal and that must be watched for when catheterization is indicated. The pediatric anesthesiologist should be familiar with the use of silicon catheters, the reasons for their failure and signs of incorrect placement. Although our patient suffered no complication after the break and embolization, the possibility of severe problems means we must monitor catheter use carefully.

Barriers to cervical cancer screening in rural Mexico.

Cervical cancer is a major health problem in Mexico. The national mortality rate due to cervical cancer was estimated at 21.8 per 100,000 among women over 15 years of age in 1994. Reasons for this high prevalence have not been defined, although it may be influenced by lack of access to health care, lack of knowledge about the Pap procedure, or cultural beliefs. While some studies have examined barriers to Pap screening, most have focused on urban samples. We conducted a pilot study using direct interviews to learn about factors that may influence cervical cancer screening among rural Mexican women. We interviewed 97 rural women between the ages of 16 and 66 and found that 52% had not received a Pap smear within the last 2 years (of that group, 62% had never received a Pap smear). In our sample, the most frequent reason for not obtaining a Pap smear was anxiety regarding physical privacy (50%). Less frequent reasons were lack of knowledge (18%) and difficulty accessing health care (14%). Women who had delivered children were significantly more likely to have received a Pap smear (71%) than women who had no children (10%), P < 0.05. The responses of many women suggest that compliance with cervical cancer screening would be enhanced by addressing cultural beliefs, encouraging conversations about women's health issues, and increasing the number of female health care providers.