The purpose of this work was to revise how well XiO treatment planning system (TPS 4.80 patch 03) Intensity Modulated Radiation Treatment (IMRT) calculations are delivered by an Elekta Synergy Platform-MLCi2 machine using Task Group 119 (TG119) benchmarked data of the American Association of Physicists in Medicine (AAPM) in order to implement future IMRT treatments at the Radiotherapy Center...
Background: Independent external audits play an important role in quality assurance in radiation oncology, for this reason the International Atomic Energy Agency (IAEA), in its technical document IAEA-TECDOC-1583, recommends a procedure to establish quality assurance of Radiotherapy Planning System (RTPS) using the IMRT Thorax Phantom (CIRS - 002LFC). The procedure is based on an anatomical...
Currently at our centre, the stereotactic program uses 6 MV cFF and forward planning techniques: cones for SRS, conformal MLC for SRT. Patients are immobilized with either the non-invasive Aktina stereotactic frame or a thermoplastic mask. Treatment localization is performed with CBCT. We are implementing DCAT and VMAT for SRT with 6 MV FFF to reduce treatment time, treat larger non-spherical...
This study provides dosimetric data from the commissioning of two Sensus SRT-100 50–100 kV X-ray units. Data collected during the commissioning process included: a) HVL, b) output (dose rate), c) applicator cone factors, and d) profiles. Percentages depth dose were not measured due to lack of resources. Farmer-type chambers (iba-FC65-G), and a thin-window parallel plate ion chamber...
Several Monte Carlo (MC) codes are available for performing radiotherapy dose calculations, with acceptable accuracy. The objective of this work is to analyze the differences in the calculations obtained by different MC codes and their impact on the absorbed dose evaluations. In order to evaluate the possible systematic differences, a comparison was made between different electromagnetic...
Relative renal function and differences in the images of kidneys through renal gammagraphy with radiopharmaceutical $^{99m}$Tc-MAG3 and $^{99m}$Tc-DMSA was compared. For the study a sample of 50 patients was analyzed, in which 75% were children. Images were acquired with a double-headed AnyScan SC gamma camera of MEDISO Company. The renal gammagraphy with $^{99m}$Tc-MAG3 was processed as a...
Since its discovery in 1935 by J. Chadwick, neutrons have been used in many fields, from power production to medical applications. In particular, G. L. Locher in 1936 came out with the idea of using neutron capture for cancer treatments. Currently the Neutron Capture Therapy (NCT) stands for a binary treatment method that combines a cancer specific Boron ($^{10}$B) or Gadolinium ($^{157}$Gd)...
After the discovery of neutrons, G. L. Locher proposed the idea of using neutron capture for cancer treatment - Neutron Capture Therapy (NCT). This treatment method combines either a Boron ($^{10}$B) or Gadolinium ($^{157}$Gd) labeled drug and an epithermal neutron beam suitable for neutron capture to take place within the treated tissues. With a branching ratio of approximately 94%, the...
In the last decades the use of the Human Amniotic Membrane (HAM) in regenerative and curative medicine has been significantly increased. The sterilization processes of the HAM are crucial for its clinical use. In order to preserve the main biophysical and biochemical properties of HAM, improvements are required in the sterilization procedures, in which some of the valuable HAM's properties are...
It is recognised worldwide that the security of radioactive materials is very important and that the design of facilities where these sources are used and stored must cater for the implementation of good security measures, including the shielding of some treatment and diagnostic rooms. The radiation protection assessment of a nuclear medicine facility consists of the evaluation of the annual...
Was designed and produced a cylindrical phantom in PMMA material for evaluate the image quality parameters: spatial resolution, high and low contrast, magnification, uniformity and reproducibility of Hounsfield numbers for Computed Tomography (CT) through the formation of images in the acquisition of tomographic images. The phantom was designed and built under the recommendations of...
The $^{85}$Kr isotope is a beta-ray emitter (gas) with a half-life of 10.76 years. It is produced in the fission of Uranium and Plutonium. The sources of this isotope are the nuclear tests, the nuclear reactors and the reprocessing of nuclear fuel. In the gas release events around reactors, the $^{85}$Kr may represent a major hazard. In beta emitters, in order to evaluate the absorbed dose...
14F7 is a murine monoclonal antibody that recognizes the ganglioside N-Glycolil GM3 and induces death in tumor cells that overexpress this ligand. Antibody fragments exhibit improved pharmacokinetic properties as compared to whole antibodies. The study was based on two assumptions: first, the h14F7-F(ab')$_2$ does not lose its biological activity; second, labelled with $^{99m}$Tc, have a more...
In this work the study of the Deposited Dose Distributions in depth by Protons and Carbon Ions in different Phantoms, was made with Monte Carlo Method. Initially, a simulation of the interaction of the charged particles (Protons and Carbon Ions) with water was constructed with the Geant4 tool (Fig.1.). The Bragg peaks and Deposited Dose Maps at multiple energies within the therapeutic range...
In lung cancer, SBRT is used to deliver high doses to a small dense GTV moving into a low-density tissue (margin generating the PTV). If IMRT or VMAT are used to treat such inhomogeneous PTV, a homogeneous dose distribution is achieved generating high photon fluence inside a 3D shell (PTV-GTV). Paradoxically the dose distribution is apparently uniform, but the GTV, which moves into the PTV,...
The availability of tools for visualize, control, and track patient specific respiratory motion could improve the accuracy in radiation therapy for thorax and abdomen tumor lesion. If smaller treatment fields are used, there is the possibility of target may move out of the treatment field resulting in an under dose to the target and surrounding normal will be exposed.The goal of this work is...
There is sufficient information in vitro and in vivo that indicates that AT1 receptor (part of the blood pressure regulated system Renin-Angiotensin) is overexpressed in malignant tumor. The losartan is one of the most studied antagonist of this receptor, for that reason, this study evaluated the fluoro-alkyl losartan-derivatives ($^{18}$FAL) as potential candidates of $^{18}$F-labeled...
Very soon is going to work in Cardiological Center of Villa Clara, Cuba, a new brand of X ray Device, (that is X Ray in C Arm), that includes electrophysiology functions, in which the irradiation time might be longer in comparison with Hemodynamic Machines and interventionist cardiology, where take place several procedures of less duration such as angiographies and angioplasties. It is shown...
This research, propose a monitoring procedure of $^{131}$I intake of nuclear medicine workers using the thyroid probe of the Nuclear Medicine Department. The Thyroid Counter used is a gamma probe, equipped with a lead shielded NaI(Tl) scintillation detector of 30x30, also was studied the gamma camera Phillips Forte with NaI(Tl) 3/8" pinhole collimator-5mm. The efficiency calibration was...
Intra-Operative radiotherapy (IORT) is a very effective technique that has begun to be used in our region. It has proven to be a good alternative as part of the breast conserving surgery. Technical success is based on the administration of high doses to the lesion in a single treatment session of radiotherapy, during the same surgical operation, with multiple clinical advantages that are not...
The optimization of patient-specific treatment planning of hyperthyroidism with $^{131}$I is a desirable goal from medical and radiation protection point of view. The purpose of this work was to develop a software based on MATLAB, capable to handle non-uniform activity distribution at voxel level and made dosimetry calculation using the “S” factor from MIRD methodology, planning the...
Total Body Irradiation (TBI) is a radiotherapy technique that consists of irradiating homogeneously the whole patients body and it is characterized by extended source to surface distances and the use of large irradiation fields. The limitations of the available input data and inherent problems with the calculation procedures make it very difficult to accurately determine the dose distributions...
In radiotherapy and nuclear medicine processes, medical physic have a preponderant participation in the correct administration of prescript doses to a patient, so that if they differ more than a predetermined value to the prescription, become in radiological accident or a mistreatment.
In this paper is exposed a quantitative and qualitative analysis, based on Risk Matrix Method, particularly...
Nanogels are extensively studied for diverse biomedical applications. One of the most relevant is the use as drugs nano-carriers for therapeutic purposes, increasing the bioactivity and transport of active components to specific sites or cells. Nanogels-based drug release formulations improve the effectiveness and safety of certain anticancer drugs and radiopharmaceuticals, minimizing its...
Purpose: The flattening filter free (FFF) mode (Elekta) was recently installed at our institution. We investigated FFF planning and delivery for stereotactic peripheral lung treatment as the increased dose rate of FFF mode can reduce the treatment time.
Methods: Ten lung cancer patients with peripheral lesions previously treated with VMAT SBRT were selected to span a range of target sizes and...
Despite the clear evidence that computed tomography provides very valuable information for diagnosis, there is a potential risk for the use of ionizing radiation. In CT, decreasing the dose of radiation increases the amount of noise in the images; therefore, the noise can hide anatomical details and decrease the detection of injuries. The Bilateral filter, proposed by Tomasi and Manduchi, is...
The Monte Carlo method (MC) has been commonly used in medical physics applications such as radiotherapy, radiation protection and nuclear medicine due to the stochastic nature of radiation and detection processes. In our country, during the last few years, new radiotherapy machines with novel technological advances have been acquired. Among this new equipment, the linear accelerator (linac)...
Sophisticated devices are used in Stereotactic Radiosurgery (SRS) for delivering small radiation beams in specific geometries. Computer planning systems are customized with specific dosimetric data corresponding to the specific machine.
At Instituto Nacional de Oncologia y Radiobiologia, an Apex micro multileafs collimator was adopted together with an Elekta Precise linear accelerator for SRS...
The IAEA is about to publish an IAEA/AAPM protocol for the dosimetry of small photon beams. The present paper inserts into an ongoing IAEA coordinated research project to test the applicability of the new code of practice.
Relative output factors were measured in water (SSD=90cm @10cm depth) for ten field sizes ranging from 0.49 to 11.3 cm of equivalent square. The collimation is made with the...
A NMR based experimental procedure to determine the dynamic viscosity ($\eta$) in Plasma solutionsis presented. An equation relating $\eta$ and the transversal proton magnetic relaxation time (T$_2$) is obtained after considering a fast exchange between the free and associated water inside the Plasma Solution, the dominant role of the associated water in proton magnetic relaxation, the...
A detailed simulation of cross radiation in the PET and CT detectors of the tomographic bimodal system for small animals ClearPET/XPAD3-CT, was made using the Geant4 Monte Carlo code. A positron emitter radioactive point source (FDG-$^{18}$F) was located in the center of the tomographic system, inside a spherical water phantom. Positron-electron annihilations occurring within the phantom...
Real-time dosimetry for radiotherapy with high spatial resolution is a growing research field. Development of new radiotherapy techniques, such as intensity-modulated radiation therapy, stereotactic radiosurgery, and high dose rate brachyterapy among others, require high performance dosimetrics techniques. Even though different kinds of detection systems have been investigated to perform...
The motivation of this analysis was the knowledge of quantitative association between CT dosimetric quantities and operational factors and devise scanner-specific optimization strategies. The measure of indexes of kerma free in air and in standard phantoms (in a Siemens Sensation CT scanner), provided the main data for identification of statistical associations with operational factors and...
The traditional scheme for X-ray production is based on the well known X-ray tube, an evolution in technology started from the experiments performed by Crookes and finally by X-rays discovery by W. Röntgen in 1895. As known, X-ray tubes are mainly based on the impact of accelerated electron onto high atomic number anodes in order to produce photons by means of Bremsstrahlung and characteristic...
In vivo dosimetry is an essential tool for quality assurance programs, being a procedure commonly performed with thermoluminescent dosimeters (TLDs) or diodes. However, a type of dosimeter that has increasing popularity in recent years is metal-oxide-semiconductor field effect transistor (MOSFET) detector. MOSFET dosimeters fulfill all the necessary characteristics to realize a in vivo...
