A new graph of soil Rn-gas transport: Radon-rose plot.

Soil radon gas movement depends on soil geology, environmental thermodynamic parameters and, micro-seismic telluric activity. Mapping radon time dependent concentration at the relaxation depth in a selected area, provide transport direction in a seismically high-risk region. Nuclear track methodology is employed to determine main gradient vector for radon transport. Applying the gradient definition, a "radon rose" graph is constructed from which prone area can be promptly identified. Results show that short time interval, Rn-transport direction may change unpredictably, however, the length of each "spoke" around the circle provides information on the soil Rn-gas probable shifts towards or from a direction per time interval. The new graph is a novelty and provide improved approach for environmental protection and radon dosimetry.

New target with low photoneutron yield for LINAC radiotherapy applications.

This paper presents three new materials composed of TiXV0,035XCuX-1,035 (X = 2, 4 and 6%), is proposed as Linear Accelerator target. Its response to electron beam based on photoneutron production, is assessed by MC simulation and nuclear track-etch methodology. The outcome is compared to a tungsten target irradiated by energetic 16 MeV electron beam. Photoneutron yield, of two energy groups (thermal and epithermal) were determined via converter matter 10B (98%) and Cd-filter by PADC-track density comparison. The multi-metal Ti2V0,07Cu97.93 target related to therapy beam quality, resulted advantageous in comparison to that provided by W-target, commonly used in the LINAC.

Seasonal variation of the S-index as it relates to the concentration of 222Rn inside a bunker that stores radioactive material.

In this work, the seasonal variation of the concentration of radon in soil and its contribution to concentrations inside of a bunker used for the storage and operation of radioactive material was studied. The measurements obtained inside and outside of the installation allowed establish a method for the calculation of the diffusion coefficient for the concrete, variable that directly influences the concentration of radon gas inside of the bunker. With the obtained results of the gamma dose rate and the concentration of radon inside the bunker, the S-index was calculated in order to determine whether the bunker would require some remediation process. The high radon gas concentration rates to which workers are exposed led to study the relative risk of contracting lung cancer (RRLC).

Shielding for transporting an 241Am-Be source for industrial applications.

Paraffin, water and water-extended polyester (WEP) were used as main moderator to design a mobile shielding for a 666 GBq 241Am-Be source used in oil industry. The shielding performance was estimated using Monte Carlo methods where the γ-rays induced by the neutron interaction with the shielding materials were also included. The spectra of neutrons and γ-rays around the shielding were estimated, as well as the total neutron and g-ray total fluences per history. The neutron source strength was used to calculate ambient dose equivalent rates, aiming to satisfy the international recommendation (2 mSv/h at the shielding surface). Moderators modify the neutron spectrum of the source reducing the amount of fast neutrons (0.5-11 MeV) and producing epithermal and thermal neutrons. During neutron transport in the moderator neutron capture and inelastic scattering produce gamma-rays. Paraffin has the best shielding performance however it is not suitable because can be affected by extreme temperatures. WEP and water have similar shielding performance, however water do not satisfy the international recommendations because at one site the neutron and γ-ray doses rates are larger than 2 mSv/h. WEP is the best option because fulfill the international recommendations, it is stable and temperatures where paraffin fails. The WEP-based shielding weights 66 kg.

Radon concentration in hydrogeothermal deposit and spas of Boyacá, Colombia.

Inhaled radon and its progenies induce health concern due to high activity-concentration in selected thermal spas of Boyacá region. Hydrogeothermal water sources in a high risk seismic area, are studied to determine by water bubbling method radon concentration values; their occurrence is between few hundreds and 2000 Bq dm-3. Deposits, existing in this area, reach at the surface soil gas radon concentration up to 210 kBq m-3. Maintenance workers, health tourists and visitor's possible detrimental health effects, are discussed in relation to radon balneotherapy beneficial aspects.

[The costs of treatment with the new antidepressants in clinical practice]. / Costes del tratamiento con nuevos antidepresivos en la práctica clínica.

OBJECTIVE: To assess if, in usual clinical practice, the patterns of use of new antidepressant are associated to different health resource utilisation. DESIGN: Naturalistic, retrospective, observational study. SETTING: Urban health center. PATIENTS: DSM-IIIR diagnostic criteria of depressive disorder and treatment with a new antidepressant (n = 328). INTERVENTIONS: Information on resource utilisation was collected in those patients treated with fluoxetine (FLX), fluvoxamine (FLV) sertraline (SER), paroxetine (PAR) and venlafaxine (VLF). Direct, indirect and total costs were compared according to the different patterns of use (stable therapy, upward dose titration, switching or augmentation) and according to the initially prescribed antidepressant. The follow-up period was 6 months. RESULTS: Direct and total daily costs of those patients with unestable therapy (upward dose titration, switching or augmentation) were 55% (p < 0.01) and 87% (p = 0.001) higher than for patients with stable therapy, respectively. Patients who initiated therapy on SER, VLF and PAR had 35% (p < 0.05), 80% (p < 0.05) and 37% (p < 0.05), respectively, higher average total costs per day than patients who initiated therapy with FLX. Regarding direct costs, patients who initiated therapy on SER and VLF had 48% (p < 0.001) and 58% (p < 0.05) higher average costs per day than patients who initiated therapy with FLX. CONCLUSIONS: New antidepressants show different patterns of use in a clinical practice setting, being FLX the agent more associated to a stable pattern of use. The pattern of use is associated to different health resource utilisation. Patients under stable therapy show lower health costs than those who need upward titration, switching or augmentation strategies. It is necessary to conduct randomized naturalistic studies to confirm these results.