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Open access

Thanigaimalai Velmurugan, Prabakar Sukumar, Chokkalingam Krishnappan and Raghavendiran Boopathy

Study of dosimetric variation due to interfraction organ movement in High Dose Rate Interstital (MUPIT) brachytherapy for gynecologic malignancies

Ten patients with cancer of uterine cervix who underwent interstitial brachytherapy using MUPIT templates were CT scanned (CT1) using which bladder, rectum and CTV were delineated. The treatment plan PCT1 was generated and optimized geometrically on the volume. CT scan (CT2) was repeated before the second fraction of the treatment CTV and critical organs were delineated. The plan (PCT2) was created by reproducing the Plan PCT1 in the CT2 images and compared with PCT1. Bladder, Rectum and CTV percentage volume variation ranges from +28.6% to -34.3%, 38.4% to -14.9% and 8.5% to -15.2% respectively. Maximum dose variation in bladder was +17.1%, in rectum was up to +410% and in CTV was -13.0%. The dose to these structures varies independently with no strong correlation with the volume variation. Hence it is suggested that repeat CT and re-planning is mandatory before second fraction execution.

Open access

Mohammed Al Asmary and Manickam Ravikumar

Position of effective electron source for shielded electron beams from a therapeutic linear accelerator

The effective electron source positions for the standard electron cones and for the shielded field sizes with cerrobend inserts were measured based on Inverse Square Law (ISL) and the Inverse Slope (IS) method for various electron energies.

The charge measurements were carried out using a 0.6 cc ion chamber (PTW, Type 30001) connected to a PTW Unidos E digital electrometer in a polystyrene phantom for electron beam energies of 6-18 MeV. The resultant charge for 100 MU setting was measured at nominal source to surface distances (SSDs) of 100-120 cm for cone and cerrobend defined field sizes.

The effective SSD (SSDeff) was found to be different for the same field size defined by electron applicator and the cerrobend shield placed in 25×25 cm standard cone. Strong dependency of SSDeff with field size and electron beam energy was noticed.

The results from the ISL and IS method are consistent, hence either of the two methods can be used to determine the effective source position. Whenever treatment is to be given with shielded electron portal, the SSDeff for that field needs to be determined. Same SSDeff as that of the standard cone can be used for minimum shielded electron portals.

Open access

Sajeev Thomas, S. Sampath, B. IndiraDevi, G. Bhanumathy, Sanjay Supe and M. Musthafa

A novel technique to evaluate the geometrical accuracy of CT-MR image fusion in Gamma Knife radiosurgery procedures

In order to optimize the accuracy of imaging in Gamma Knife radiosurgery using the image fusion options available in the Leksell gamma plan. Phantom images from 1.5 Tesla MRI Scan (Magnetom vision - Siemens) and Computed Tomography images from Philips Brilliance 16 CT scanner were used for image fusion in Gammaplan treatment planning system. The images were fused using co-registration technique using multiview and imagemerge modules. Stereotactic coordinates were then calculated for known targets. Vector distances from the centre of the Leksell coordinate system to five known targets were measured in CT, MR and CT-MR fused images and compared with geometrical measurements. The mean values of maximum absolute errors were 0.34 mm, 0.41 mm.0.38 mm (along x-axis), 0.43 mm, 1.53 mm, 0.62 mm (along y-axis) and 0.75 mm 2.02 mm, 0.93 mm (along z-axis) for CT, MR and CT-MR fused image data respectively. The mean error in calculating the vector distances from the center of the Leksell coordinate system (100, 100, 100) to the known target volumes are 0.22 mm, 0.8 mm and 0.43 mm for CT, MR and CT-MR fused images, respectively. Image fusion functions available in gamma plan are useful for combining the features of CT and MR imaging modalities. These methods are highly useful in clinical situations where the error associated with Magnetic Resonance Imaging is beyond acceptable levels.

Open access

Sanjay Supe

Mobile phones and sleep - A review

The increasing use of mobile phones has raised concerns regarding the potential health effects of exposure to the radiofrequency electromagnetic fields. An increasing amount research related to mobile phone use has focussed on the possible effects of mobile phone exposure on human brain activity and function. In particular, the use of sleep research has become a more widely used technique for assessing the possible effects of mobile phones on human health and wellbeing especially in the investigation of potential changes in sleep architecture resulting from mobile phone use. Acute exposure to a mobile phone prior to sleep significantly enhances electroencephalogram spectral power in the sleep spindle frequency range. This mobile phone-induced enhancement in spectral power is largely transitory and does not linger throughout the night. Furthermore, a reduction in rapid eye movement sleep latency following mobile phone exposure was also found, although interestingly, neither this change in rapid eye movement sleep latency or the enhancement in spectral power following mobile phone exposure, led to changes in the overall quality of sleep. In conclusion, a short exposure to the radiofrequency electromagnetic fields emitted by a mobile phone handset immediately prior to sleep is sufficient to induce changes in brain activity in the initial part of sleep. The consequences or functional significance of this effect are currently unknown and it would be premature to draw conclusions about possible health consequences.

Open access

Ciszewska Katarzyna, Dymecka Malgorzata, Pliszczynski Tomasz and Osko Jakub

Improvement of the quality of effective dose estimation by interlaboratory comparisons

Radiation Protection Measurements Laboratory (RPLM) of the Institute of Atomic Energy POLATOM determines radionuclides in human urine to estimate the effective dose. Being an accredited laboratory, RPLM participated in interlaboratory comparisons in order to assure the quality of services concerning monitoring of internal contamination. The purpose of the study was to examine the effect of interlaboratory comparisons on the accuracy of the provided measurements. The results regarding tritium (3H) and strontium (90Sr) determination, obtained within the radiotoxicological intercomparison exercises, organized by PROCORAD, in 2005-2010, were analyzed and the methods used by the laboratory were verified and improved.

Open access

Chong Zhang and Xiaolin Yu

Estimating mental fatigue based on electroencephalogram and heart rate variability

The effects of long term mental arithmetic task on psychology are investigated by subjective self-reporting measures and action performance test. Based on electroencephalogram (EEG) and heart rate variability (HRV), the impacts of prolonged cognitive activity on central nervous system and autonomic nervous system are observed and analyzed. Wavelet packet parameters of EEG and power spectral indices of HRV are combined to estimate the change of mental fatigue. Then wavelet packet parameters of EEG which change significantly are extracted as the features of brain activity in different mental fatigue state, support vector machine (SVM) algorithm is applied to differentiate two mental fatigue states. The experimental results show that long term mental arithmetic task induces the mental fatigue. The wavelet packet parameters of EEG and power spectral indices of HRV are strongly correlated with mental fatigue. The predominant activity of autonomic nervous system of subjects turns to the sympathetic activity from parasympathetic activity after the task. Moreover, the slow waves of EEG increase, the fast waves of EEG and the degree of disorder of brain decrease compared with the pre-task. The SVM algorithm can effectively differentiate two mental fatigue states, which achieves the maximum classification accuracy (91%). The SVM algorithm could be a promising tool for the evaluation of mental fatigue.

Fatigue, especially mental fatigue, is a common phenomenon in modern life, is a persistent occupational hazard for professional. Mental fatigue is usually accompanied with a sense of weariness, reduced alertness, and reduced mental performance, which would lead the accidents in life, decrease productivity in workplace and harm the health. Therefore, the evaluation of mental fatigue is important for the occupational risk protection, productivity, and occupational health.

Open access

S. Inyang, N. Egbe, I. Inyang and D. Oshi

Baseline survey of level of quality control in medical radiology in Cross River State, Nigeria

Quality control (QC) in radiology is meant to ensure that accurate diagnoses are obtained with radiation doses kept as low as reasonably achievable. It is also a fundamental requirement by the Regulatory Authorities in issuing operational license to operators of radiology facilities. In Nigeria, QC issues in Radiation Medicine have recently been introduced and are being enforced by the Nigerian Nuclear Regulatory Authority (NNRA). The level of QC practice in the radiology facilities in Cross River State, Nigeria was evaluated to obtain baseline information that could be relied on in the future to determine the level of improvement. It was observed that radiology practitioners appreciate QC and its importance in their practice, the present low level of its implementation notwithstanding.

Open access

Alicja Siewnicka, Bartlomiej Fajdek and Krzysztof Janiszowski

Application of a PExSim for modeling a POLVAD artificial heart and the human circulatory system with left ventricle assistance

This paper presents a model of the human circulatory system with the possible addition of a parallel assist device, which was developed for the purpose of artificial heart monitoring. Information about an identification experiment of an extracorporeal ventricle assist device POLVAD is included. The modelling methods applied and the corresponding functional blocks in a PExSim package are presented. The results of the simulation for physiological conditions, left ventricle failure and pathological conditions with parallel assistance are included.

Open access

Katarzyna Tyminska, Karol Jezierski and Jakub Osko

A virtual model of the patient's head for BNCT

The aim of the present work was creating a virtual phantom of a human head for BNCT, as a part of the BNCT programme project. This model is an amplification of the simple model described in earlier publications. It takes into account the major head organs as well as the scalp and skull. The chemical composition of all tissues was modelled according to the recommendations of the ICRP. The organs were parameterized using mathematical formulas based on the human head magnetic resonance images. The model was used for calculating the thermal neutron flux and the injuring (fast neutron, nitrogen and gamma) dose components for the head irradiated using the therapeutic neutron beam, whose parameters were obtained as the result of the modelling of the filter/moderator system for the BNCT therapeutic beam from the MARIA reactor.

Open access

Ryszard Krzyminiewski, Zdzislaw Kruczynski, Aleksander Stepien and Bernadeta Dobosz

Spin traps in the detection of free radicals in the blood of patients with ischemia

Electron Paramagnetic Resonance and a nitrosobenzene spin trap were used to investigate free radicals in the human blood after angioplasty treatment. The nitrosobenzene anion radical was determined using EPR measurements and quantum-mechanical calculations. Differences were observed in the concentration of free radicals before and after angioplasty treatment. These results were compared with myocardium damage parameters (CPK, MB and TnT).