ABSTRACT
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.
Subject(s)
Mammography/standards , Breast Neoplasms/diagnostic imaging , Breast Neoplasms/epidemiology , Breast Neoplasms/prevention & control , Female , Humans , Mass Screening , Mexico/epidemiologyABSTRACT
Calculations of fluence and absorbed dose in head tissues due to different photon energies were carried out using the MCNPX code, to simulate two models of a patient's head: one spherical and another more realistic ellipsoidal. Both head models had concentric shells to describe the scalp skin, the cranium and the brain. The tumor was located at the center of the head and it was a 1 cm-radius sphere. The MCNPX code was run for different energies. Results showed that the fluence decreases as the photons pass through the different head tissues. It can be observed that, although the fluence into the tumor is different for both head models, absorbed dose is the same.
Subject(s)
Head and Neck Neoplasms/radiotherapy , Models, Biological , Photons , Radiotherapy Dosage , HumansABSTRACT
OBJECTIVE: To define whether the rs9939609 FTO (fat mass and obesity associated) single nucleotide polymorphism (SNP) is associated with anthropometric measurements and its modulation by educational level in a Mediterranean population. METHODS: We studied 3 independent adult samples: a random sample (n = 1580) from the general population (GP), obese hospital patients (OHP) (n = 203) and elderly subjects (n = 1027) with high cardiovascular risk (HCR). Weight and height were directly measured. Education and physical activity (PA) were measured using questionnaires. RESULTS: The rs9939609 presented heterogeneous associations with BMI. In the GP, the minor A-allele was significantly associated with greater BMI, following a co-dominant pattern (P = 0.009), whereas in the OHP this association was recessive (P = 0.004). Conversely, we did not find a significant association with BMI in the HCR group (P < 0.596). In the GP we found a significant interaction between the FTO SNP and education (P = 0.048). In the stratified analysis, no association of the FTO SNP with greater BMI in university subjects was detected (P = 0.786), whereas the association was observed in non-university subjects (P = 0.001). The FTO × education interaction (P = 0.020) was also observed in determining obesity risk in the GP. A-allele carriers had a greater risk of being obese only if they had no university education (OR: 1.56; 95%CI: 1.09-2.23 for TA and OR: 2.01; 95%CI: 1.27-3.26 for AA subjects). The interaction of the FTO with education remained significant even after adjustment for PA. CONCLUSIONS: The association of the FTO SNP with greater BMI and obesity risk in the GP was strongly modulated by education.
Subject(s)
Body Mass Index , Educational Status , Obesity/genetics , Polymorphism, Single Nucleotide , Proteins/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Alpha-Ketoglutarate-Dependent Dioxygenase FTO , Anthropometry , Chi-Square Distribution , Female , Gene Frequency , Genetic Predisposition to Disease , Humans , Linear Models , Logistic Models , Male , Middle Aged , Motor Activity , Multivariate Analysis , Obesity/diagnosis , Obesity/epidemiology , Odds Ratio , Phenotype , Prevalence , Risk Assessment , Risk Factors , Spain/epidemiology , Surveys and Questionnaires , Young AdultABSTRACT
This work describes an algorithm for absorbed dose evaluation in the region of X-ray diagnostic energy based on the response of CaSO(4):Dy thermoluminescence powder detectors. The absorbed dose was calculated using Monte Carlo simulation code (MCSC) and then compared to the experimental TLD results for X-rays effective energies (60)Co gamma radiation. In order to study the photon interaction in the matter, a cylindrical model of 1 cm(3) was used. The gamma radiation source was placed at 100 cm to the object; the source is considered as an isotropic source of (60)Co. The energy deposited into the cylindrical model was determined by the Monte Carlo N-particle (MCNPX) method. Measurements of the TL phosphors were obtained by irradiating the powder by gamma radiation. TL glow curve of CaSO(4):Dy after gamma irradiated at a 1 Gy of absorbed dose was then obtained.
