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Author  |
Candela-Juan, C.; Niatsetski, Y.; van der Laarse, R.; Granero, D.; Ballester, F.; Perez-Calatayud, J.; Vijande, J. |
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Title |
Design and characterization of a new high-dose-rate brachytherapy Valencia applicator for larger skin lesions |
Type |
Journal Article |
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Year |
2016 |
Publication |
Medical Physics |
Abbreviated Journal |
Med. Phys. |
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Volume |
43 |
Issue |
4 |
Pages |
1639-1648 |
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Keywords |
skin applicator; Valencia applicator; HDR brachytherapy; dosimetry; Monte Carlo |
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Abstract |
Purpose: The aims of this study were (i) to design a new high-dose-rate (HDR) brachytherapy applicator for treating surface lesions with planning target volumes larger than 3 cm in diameter and up to 5 cm in size, using the microSelectron-HDR or Flexitron afterloader (Elekta Brachytherapy) with a Ir-192 source; (ii) to calculate by means of the Monte Carlo (MC) method the dose distribution for the new applicator when it is placed against a water phantom; and (iii) to validate experimentally the dose distributions in water. Methods: The PENELOPE2008 MC code was used to optimize dwell positions and dwell times. Next, the dose distribution in a water phantom and the leakage dose distribution around the applicator were calculated. Finally, MC data were validated experimentally for a 192Ir mHDR-v2 source by measuring (i) dose distributions with radiochromic EBT3 films (ISP); (ii) percentage depth-dose (PDD) curve with the parallel-plate ionization chamber Advanced Markus (PTW); and (iii) absolute dose rate with EBT3 films and the PinPoint T31016 (PTW) ionization chamber. Results: The new applicator is made of tungsten alloy (Densimet) and consists of a set of interchangeable collimators. Three catheters are used to allocate the source at prefixed dwell positions with preset weights to produce a homogenous dose distribution at the typical prescription depth of 3 mm in water. The same plan is used for all available collimators. PDD, absolute dose rate per unit of air kerma strength, and off-axis profiles in a cylindrical water phantom are reported. These data can be used for treatment planning. Leakage around the applicator was also scored. The dose distributions, PDD, and absolute dose rate calculated agree within experimental uncertainties with the doses measured: differences of MC data with chamber measurements are up to 0.8% and with radiochromic films are up to 3.5%. Conclusions: The new applicator and the dosimetric data provided here will be a valuable tool in clinical practice, making treatment of large skin lesions simpler, faster, and safer. Also the dose to surrounding healthy tissues is minimal. |
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Address |
[Candela-Juan, C.; Perez-Calatayud, J.] La Fe Univ & Polytech Hosp, Dept Radiat Oncol, Valencia 46026, Spain, Email: ccanjuan@gmail.com |
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Publisher |
Amer Assoc Physicists Medicine Amer Inst Physics |
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Language |
English |
Summary Language |
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Original Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0094-2405 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000373711000007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2620 |
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Author |
Candela-Juan, C.; Vijande, J.; Garcia-Martinez, T.; Niatsetski, Y.; Nauta, G.; Schuurman, J.; Ouhib, Z.; Ballester, F.; Perez-Calatayud, J. |
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Title |
Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry |
Type |
Journal Article |
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Year |
2015 |
Publication |
Medical Physics |
Abbreviated Journal |
Med. Phys. |
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Volume |
42 |
Issue |
8 |
Pages |
4954-4964 |
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Keywords |
x-ray beams; electronic brachytherapy; surface applicators; dosimetry; uncertainty |
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Abstract |
Purpose: A surface electronic brachytherapy (EBT) device is in fact an x-ray source collimated with specific applicators. Low-energy (<100 kVp) x-ray beam dosimetry faces several challenges that need to be addressed. A number of calibration protocols have been published for x-ray beam dosimetry. The media in which measurements are performed are the fundamental difference between them. The aim of this study was to evaluate the surface dose rate of a low-energy x-ray source with small field applicators using different calibration standards and different small-volume ionization chambers, comparing the values and uncertainties of each methodology. Methods: The surface dose rate of the EBT unit Esteya (Elekta Brachytherapy, The Netherlands), a 69.5 kVp x-ray source with applicators of 10, 15, 20, 25, and 30 mm diameter, was evaluated using the AAPM TG-61 (based on air kerma) and International Atomic Energy Agency (IAEA) TRS-398 (based on absorbed dose to water) dosimetry protocols for low-energy photon beams. A plane parallel T34013 ionization chamber (PTW Freiburg, Germany) calibrated in terms of both absorbed dose to water and air kerma was used to compare the two dosimetry protocols. Another PTW chamber of the same model was used to evaluate the reproducibility between these chambers. Measurements were also performed with two different Exradin A20 (Standard Imaging, Inc., Middleton, WI) chambers calibrated in terms of air kerma. Results: Differences between surface dose rates measured in air and in water using the T34013 chamber range from 1.6% to 3.3%. No field size dependence has been observed. Differences are below 3.7% when measurements with the A20 and the T34013 chambers calibrated in air are compared. Estimated uncertainty (with coverage factor k = 1) for the T34013 chamber calibrated in water is 2.2%-2.4%, whereas it increases to 2.5% and 2.7% for the A20 and T34013 chambers calibrated in air, respectively. The output factors, measured with the PTW chambers, differ by less than 1.1% for any applicator size when compared to the output factors that were measured with the A20 chamber. Conclusions: Measurements using both dosimetric protocols are consistent, once the overall uncertainties are considered. There is also consistency between measurements performed with both chambers calibrated in air. Both the T34013 and A20 chambers have negligible stem effect. Any x-ray surface brachytherapy system, including Esteya, can be characterized using either one of these calibration protocols and ionization chambers. Having less correction factors, lower uncertainty, and based on measurements, performed in closer to clinical conditions, the TRS-398 protocol seems to be the preferred option. |
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Address |
[Candela-Juan, C.; Perez-Calatayud, J.] La Fe Univ, Dept Radiat Oncol, Valencia 46026, Spain, Email: ccanjuan@gmail.com |
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Corporate Author |
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Thesis |
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Publisher |
Amer Assoc Physicists Medicine Amer Inst Physics |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0094-2405 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000358933000051 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2323 |
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Author |
Carames, T.F.; Fontoura, C.E.; Krein, G.; Tsushima, K.; Vijande, J.; Valcarce, A. |
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Title |
Hadronic molecules with a (D)over-bar meson in a medium |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
94 |
Issue |
3 |
Pages |
034009 - 10pp |
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Keywords |
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Abstract |
We study the effect of a hot and dense medium on the binding energy of hadronic molecules with open-charm mesons. We focus on a recent chiral quark-model-based prediction of a molecular state in the N (D) over bar system. We analyze how the two-body thresholds and the hadron-hadron interactions are modified when quark and meson masses and quark-meson couplings change in a function of the temperature and baryon density according to predictions of the Nambu-Jona-Lasinio model. We find that in some cases the molecular binding is enhanced in medium as compared to their free-space binding. We discuss the consequences of our findings for the search for exotic hadrons in high-energy heavy-ion collisions as well as in the forthcoming facilities FAIR or J-PARC. |
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Address |
[Carames, T. F.; Valcarce, A.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain, Email: carames@usal.es; |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2470-0010 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000380961500002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2780 |
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Author |
Carames, T.F.; Fontoura, C.E.; Krein, G.; Vijande, J.; Valcarce, A. |
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Title |
Charmed baryons in nuclear matter |
Type |
Journal Article |
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Year |
2018 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
98 |
Issue |
11 |
Pages |
114019 - 9pp |
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Keywords |
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Abstract |
We study the temperature and baryon density dependence of the masses of the lightest charmed baryons Lambda(c), Sigma(c) and Sigma(c)*. We also look at the effects of the temperature and baryon density on the binding energies of the Lambda N-c and Lambda(c)Lambda(c) systems. Baryon masses and baryon-baryon interactions are evaluated within a chiral constituent quark model. Medium effects are incorporated in those parameters of the model related to the dynamical breaking of chiral symmetry, which are the masses of the constituent quarks, the sigma and pi meson masses, and quark-meson couplings. We find that while the in-medium Lambda(c) mass decreases monotonically with temperature, those of Sigma(c) and Sigma(c)* have a nonmonotonic dependence. These features can be understood in terms of a simple group theory analysis regarding the one-gluon exchange interaction in those hadrons. The in-medium Lambda N-c and Lambda(c)Lambda(c) interactions are governed by a delicate balance involving a stronger attraction due to the decrease of the sigma meson mass, suppression of coupled-channel effects and lower thresholds, leading to shallow bound states with binding energies of a few MeV. The Lambda(c) baryon could possibly be bound to a large nucleus, in qualitative agreement with results based on relativistic mean field models or QCD sum rules. Ongoing experiments at RHIC or LHCb or the planned ones at FAIR and J-PARC may take advantage of the present results. |
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Address |
[Carames, T. F.; Valcarce, A.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain, Email: carames@usal.es; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2470-0010 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000454167100004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3854 |
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Author |
Carames, T.F.; Valcarce, A.; Vijande, J. |
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Title |
Too many X's, Y's and Z's? |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
709 |
Issue |
4-5 |
Pages |
358-361 |
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Keywords |
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Abstract |
A large number of new states have been reported during the last few years in charmonium spectroscopy above the charmed meson production threshold. They have been called X's, Y's, and Z's. We reflect on the influence of thresholds on heavy meson spectroscopy comparing different flavor sectors and quantum numbers. The validity of a quark-model picture above open-flavor thresholds would severely restrict the number of channels that may lodge meson-meson molecules. |
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Address |
[Carames, T. F.; Valcarce, A.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain, Email: valcarce@usal.es |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0370-2693 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000302454700005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
978 |
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