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Néa Ionía, Greece

Schwarz M.,Trento Hospital | Schwarz M.,National Institute of Nuclear Physics, Italy | Molinelli S.,Medical Physics Unit
Physica Medica | Year: 2016

The treatment of prostate cancer with either protons or carbon ions is not a novelty, and several thousands of patients were treated with hadrontherapy in the past decades. The standard treatment approach consisted in two lateral opposed fields for both protons and carbon ions, mostly delivered with scattered beams and using conventional fractionation and hypofractionation for protons and carbon ions, respectively. Similar (RBE-weighted and BED) doses to photon therapy (XRT) have been delivered, with comparable results in terms of both local control and toxicity. The advancements in dose deposition and image guidance of the early '00s that improved the quality of XRT treatments and then allowed for hypofractionation, are being matched with some delay by hadrontherapy in these very years. Pencil beam scanning is now the norm in proton therapy, and volumetric image guidance is being developed in all new hadrontherapy facilities. There is therefore the possibility of truly taking advantage of superior dose distributions of hadrons and safely apply it to innovative treatment protocols, such as an intraprostatic boost and the treatment of larger volume for advanced stage disease. This full integration between the best of technology and new clinical approaches is probably necessary in order to obtain clinical results that are truly superior to the current state of the art of XRT. © 2016 Associazione Italiana di Fisica Medica. Source

Tsapaki V.,Medical Physics Unit | Rehani M.,International Atomic Energy Agency | Saini S.,Massachusetts General Hospital
Seminars in Ultrasound, CT and MRI | Year: 2010

The rapid technological developments in computed tomography (CT) have enabled many new clinical applications in the abdominal region. Abdomen CT is considered as a high radiation dose examination due to the large number of radiosensitive organs in the field of view. CT radiation dose has received a lot of attention not only by the medical specialties and researchers, but also by patients and media. This article reviews the situation on radiation dose and risk and provides practical guidelines to effectively manage the radiation dose without losing the benefits and maintaining diagnostic confidence in CT procedures. © 2010 Elsevier Inc. All rights reserved. Source

Singh M.,University of Delhi | Sahare P.D.,University of Delhi | Kumar P.,Medical Physics Unit
Radiation Measurements | Year: 2013

A new highly sensitive, low-Z (Zeff ≈ 10.8) TLD phosphor, Eu3+ doped NaLi2PO4, was successfully synthesized via solid state diffusion method. The formation of the single phase compound was confirmed by Powder X-Ray diffraction (PXRD) analysis. Variation of the doping level has shown that the impurity (Eu3+) concentration for maximum TL sensitivity is 0.5 mol%. Heat treatments given to achieve the high TL sensitivity of this phosphor also showed that it needs to be annealed at 973 K for 1 h. Incorporation of the impurity in the Eu+3 states was confirmed by the PL emission peaks. The TL glow curve consists of a prominent dosimetry peak at around 458 K besides small shoulders on both sides at around 400 and 500 K. The dose response of the phosphor was found to be sub-linear up to 10 Gy of the dose and later it becomes linear till it start saturating beyond 1 kGy. The TL sensitivity of the newly developed NaLi2PO 4:Eu3+ phosphor to γ radiation from 137Cs (in the linear dose range) was compared to some standard commercially available phosphors, such as, TLD-100, TLD-400, TLD-700H and TLD-900. It was found to be much more sensitive than these phosphors except TLD-700H, which is ∼2 times more sensitive. Easy method of synthesis, simple glow curve structure, high sensitivity, low fading, wide range of doses and very good reusability make the phosphor a suitable candidate for the TL dosimetry. © 2013 Elsevier Ltd. All rights reserved. Source

Tsapaki V.,Medical Physics Unit
Imaging in Medicine | Year: 2010

Interventional procedures are becoming routine around the world, owing to their successful clinical outcome and improved patient safety. However, they can be difficult and demanding, since the physician must simultaneously consider many technical and clinical aspects. Although the patients condition carries a more substantial risk compared with radiation dose, the increasing number of reports of adult radiation injuries has highlighted various issues of patient radiation safety. Unfortunately, most operators are unaware of the high doses delivered and possible radiation injuries. This article summarizes current, available information regarding benefits and risks of radiation exposure during interventional cardiology procedures, clarifies dose descriptors and presents current levels of patient radiation doses for various interventional cardiology procedures. © 2010 Future Medicine Ltd. Source

Fiandra C.,University of Turin | Fusella M.,University of Turin | Giglioli F.R.,Medical Physics Unit | Filippi A.R.,University of Turin | And 2 more authors.
Medical Physics | Year: 2013

Purpose: Patient-specific quality assurance in volumetric modulated arc therapy (VMAT) brain stereotactic radiosurgery raises specific issues on dosimetric procedures, mainly represented by the small radiation fields associated with the lack of lateral electronic equilibrium, the need of small detectors and the high dose delivered (up to 30 Gy). Gafchromic™ EBT2 and EBT3 films may be considered the dosimeter of choice, and the authors here provide some additional data about uniformity correction for this new generation of radiochromic films. Methods: A new analysis method using blue channel for marker dye correction was proposed for uniformity correction both for EBT2 and EBT3 films. Symmetry, flatness, and field-width of a reference field were analyzed to provide an evaluation in a high-spatial resolution of the film uniformity for EBT3. Absolute doses were compared with thermoluminescent dosimeters (TLD) as baseline. VMAT plans with multiple noncoplanar arcs were generated with a treatment planning system on a selected pool of eleven patients with cranial lesions and then recalculated on a water-equivalent plastic phantom by Monte Carlo algorithm for patient-specific QA. 2D quantitative dose comparison parameters were calculated, for the computed and measured dose distributions, and tested for statistically significant differences. Results: Sensitometric curves showed a different behavior above dose of 5 Gy for EBT2 and EBT3 films; with the use of inhouse marker-dye correction method, the authors obtained values of 2.5% for flatness, 1.5% of symmetry, and a field width of 4.8 cm for a 5 × 5 cm2 reference field. Compared with TLD and selecting a 5% dose tolerance, the percentage of points with ICRU index below 1 was 100% for EBT2 and 83% for EBT3. Patients analysis revealed statistically significant differences (p < 0.05) between EBT2 and EBT3 in the percentage of points with gamma values <1 (p = 0.009 and p = 0.016); the percent difference as well as the mean difference between calculated and measured isodoses (20% and 80%) were found not to be significant (p = 0.074, p = 0.185, and p = 0.57). Conclusions: Excellent performances in terms of dose homogeneity were obtained using a new blue channel method for marker-dye correction on both EBT2 and EBT3 Gafchromic™ films. In comparison with TLD, the passing rates for the EBT2 film were higher than for EBT3; a good agreement with estimated data by Monte Carlo algorithm was found for both films, with some statistically significant differences again in favor of EBT2. These results suggest that the use of Gafchromic™ EBT2 and EBT3 films is appropriate for dose verification measurements in VMAT stereotactic radiosurgery; taking into account the uncertainty associated with Gafchromic film dosimetry, the use of adequate action levels is strongly advised, in particular, for EBT3. © 2013 American Association of Physicists in Medicine. Source

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