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Author |
Rivard, M.J.; Granero, D.; Perez-Calatayud, J.; Ballester, F. |
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Title |
Influence of photon energy spectra from brachytherapy sources on Monte Carlo simulations of kerma and dose rates in water and air |
Type |
Journal Article |
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Year |
2010 |
Publication |
Medical Physics |
Abbreviated Journal |
Med. Phys. |
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Volume |
37 |
Issue  |
2 |
Pages |
869-876 |
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Keywords |
biomedical materials; brachytherapy; dosimetry; iodine; iridium; Monte Carlo methods; palladium; radioisotopes |
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Abstract |
Methods: For Ir-192, I-125, and Pd-103, the authors considered from two to five published spectra. Spherical sources approximating common brachytherapy sources were assessed. Kerma and dose results from GEANT4, MCNP5, and PENELOPE-2008 were compared for water and air. The dosimetric influence of Ir-192, I-125, and Pd-103 spectral choice was determined. Results: For the spectra considered, there were no statistically significant differences between kerma or dose results based on Monte Carlo code choice when using the same spectrum. Water-kerma differences of about 2%, 2%, and 0.7% were observed due to spectrum choice for Ir-192, I-125, and Pd-103, respectively (independent of radial distance), when accounting for photon yield per Bq. Similar differences were observed for air-kerma rate. However, their ratio (as used in the dose-rate constant) did not significantly change when the various photon spectra were selected because the differences compensated each other when dividing dose rate by air-kerma strength. Conclusions: Given the standardization of radionuclide data available from the National Nuclear Data Center (NNDC) and the rigorous infrastructure for performing and maintaining the data set evaluations, NNDC spectra are suggested for brachytherapy simulations in medical physics applications. |
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Address |
[Rivard, Mark J.] Tufts Univ, Sch Med, Dept Radiat Oncol, Boston, MA 02111 USA, Email: mrivard@tuftsmedicalcenter.org |
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Amer Assoc Physicists Medicine Amer Inst Physics |
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English |
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ISSN |
0094-2405 |
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Notes |
ISI:000274075600048 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
504 |
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Author |
Granero, D.; Perez-Calatayud, J.; Vijande, J.; Ballester, F.; Rivard, M.J. |
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Title |
Limitations of the TG-43 formalism for skin high-dose-rate brachytherapy dose calculations |
Type |
Journal Article |
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Year |
2014 |
Publication |
Medical Physics |
Abbreviated Journal |
Med. Phys. |
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Volume |
41 |
Issue |
2 |
Pages |
021703 - 8pp |
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Keywords |
HDR; brachytherapy; skin; Monte Carlo; Geant4; Co-60; Ir-192; Yb-169 |
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Abstract |
Purpose: In skin high-dose-rate (HDR) brachytherapy, sources are located outside, in contact with, or implanted at some depth below the skin surface. Most treatment planning systems use the TG-43 formalism, which is based on single-source dose superposition within an infinite water medium without accounting for the true geometry in which conditions for scattered radiation are altered by the presence of air. The purpose of this study is to evaluate the dosimetric limitations of the TG-43 formalism in HDR skin brachytherapy and the potential clinical impact. Methods: Dose rate distributions of typical configurations used in skin brachytherapy were obtained: a 5 cm x 5 cm superficial mould; a source inside a catheter located at the skin surface with and without backscatter bolus; and a typical interstitial implant consisting of an HDR source in a catheter located at a depth of 0.5 cm. Commercially available HDR Co-60 and Ir-192 sources and a hypothetical Yb-169 source were considered. The Geant4Monte Carlo radiation transport code was used to estimate dose rate distributions for the configurations considered. These results were then compared to those obtained with the TG-43 dose calculation formalism. In particular, the influence of adding bolus material over the implant was studied. Results: For a 5 cm x 5 cm Ir-192 superficial mould and 0.5 cm prescription depth, dose differences in comparison to the TG-43 method were about -3%. When the source was positioned at the skin surface, dose differences were smaller than -1% for Co-60 and Ir-192, yet -3% for Yb-169. For the interstitial implant, dose differences at the skin surface were -7% for Co-60, -0.6% for Ir-192, and -2.5% for Yb-169. Conclusions: This study indicates the following: (i) for the superficial mould, no bolus is needed; (ii) when the source is in contact with the skin surface, no bolus is needed for either Co-60 and Ir-192. For lower energy radionuclides like Yb-169, bolus may be needed; and (iii) for the interstitial case, at least a 0.1 cm bolus is advised for Co-60 to avoid underdosing superficial target layers. For Ir-192 and Yb-169, no bolus is needed. For those cases where no bolus is needed, its use might be detrimental as the lack of radiation scatter may be beneficial to the patient, although the 2% tolerance for dose calculation accuracy recommended in the AAPM TG-56 report is not fulfilled. |
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[Granero, Domingo] Hosp Gen Univ, ERESA, Dept Radiat Phys, Valencia 46014, Spain, Email: dgranero@eresa.com |
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Amer Assoc Physicists Medicine Amer Inst Physics |
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English |
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ISSN |
0094-2405 |
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Notes |
WOS:000331213300006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1704 |
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Author |
Ibanez-Rosello, B.; Bautista-Ballesteros, J.A.; Candela-Juan, C.; Villaescusa, J.I.; Ballester, F.; Vijande, J.; Perez-Calatayud, J. |
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Title |
Evaluation of the shielding in a treatment room with an electronic brachytherapy unit |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of Radiological Protection |
Abbreviated Journal |
J. Radiol. Prot. |
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Volume |
37 |
Issue |
2 |
Pages |
N5-N12 |
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Keywords |
Esteya; electronic brachytherapy; shielding; radiation protection |
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Abstract |
Esteya (R) (Elekta Brachytherapy, Veenendaal, The Netherlands) is an electronic brachytherapy (eBT) system based on a 69.5 kVp x-ray source and a set of collimators of 1 to 3 cm in diameter, used for treating non-melanoma skin cancer lesions. This study aims to estimate room shielding requirements for this unit. The non-primary (scattered and leakage) ambient dose equivalent rates were measured with a Berthold LB-133 monitor (Berthold Technologies, Bad Wildbad, Germany). The latter ranges from 17 mSv h(-1) at 0.25 m distance from the x-ray source to 0.1 mSv h(-1) at 2.5 m. The necessary room shielding was then estimated following US and some European guidelines. The room shielding for all barriers considered was below 2 mmPb. The dose to a companion who, exceptionally, would stay with the patient during all treatment was estimated to be below 1 mSv if a leaded apron is used. In conclusion, Esteya shielding requirements are minimal. |
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Address |
[Ibanez-Rosello, Blanca; Ignacio Villaescusa, Juan] La Fe Univ, Radioprotect Dept, E-46026 Valencia, Spain, Email: blanca.ibanez.rosello@gmail.com |
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Publisher |
Iop Publishing Ltd |
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English |
Summary Language |
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Series Volume |
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ISSN |
0952-4746 |
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Notes |
WOS:000413778600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
3344 |
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Author |
Quintero-Quintero, A.; Patiño-Camargo, G.; Soriano, A.; Palma, J.D.; Vilar-Palop, J.; Pujades, M.C.; Llorca-Domaica, N.; Ballester, F.; Vijande, J.; Candela-Juan, C. |
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Title |
Calibration of a thermoluminescent dosimeter worn over lead aprons in fluoroscopy guided procedures |
Type |
Journal Article |
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Year |
2018 |
Publication |
Journal of Radiological Protection |
Abbreviated Journal |
J. Radiol. Prot. |
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Volume |
38 |
Issue |
2 |
Pages |
549-563 |
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Keywords |
backscatter correction factor; TLD; lead apron; fluoroscopy; eye lens dose |
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Abstract |
Fluoroscopy guided interventional procedures provide remarkable benefits to patients. However, medical staff working near the scattered radiation field may be exposed to high cumulative equivalent doses, thus requiring shielding devices such as lead aprons and thyroid collars. In this situation, it remains an acceptable practice to derive equivalent doses to the eye lenses or other unprotected soft tissues with a dosimeter placed above these protective devices. Nevertheless, the radiation backscattered by the lead shield differs from that generated during dosimeter calibration with a water phantom. In this study, a passive personal thermoluminescent dosimeter (TLD) was modelled by means of the Monte Carlo (MC) code Penelope. The results obtained were validated against measurements performed in reference conditions in a secondary standard dosimetry laboratory. Next, the MC model was used to evaluate the backscatter correction factor needed for the case where the dosimeter is worn over a lead shield to estimate the personal equivalent dose H-p(0.07) to unprotected soft tissues. For this purpose, the TLD was irradiated over a water slab phantom with a photon beam representative of the result of a fluoroscopy beam scattered by a patient. Incident beam angles of 0 degrees and 60 degrees, and lead thicknesses between the TLD and phantom of 0.25 and 0.5 mm Pb were considered. A backscatter correction factor of 1.23 (independent of lead thickness) was calculated comparing the results with those faced in reference conditions (i.e., without lead shield and with an angular incidence of 0 degrees). The corrected dose algorithm was validated in laboratory conditions with dosi-meters irradiated over a thyroid collar and angular incidences of 0 degrees, 40 degrees and 60 degrees, as well as with dosimeters worn by interventional radiologists and cardiologists. The corrected dose algorithm provides a better approach to estimate the equivalent dose to unprotected soft tissues such as eye lenses. Dosimeters that are not shielded from backscatter radiation might underestimate personal equivalent doses when worn over a lead apron and, therefore, should be specifically characterized for this purpose. |
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[Quintero-Quintero, A.; Patino-Camargo, G.] Univ Valencia, Dept Atom Mol & Nucl Phys, E-46100 Burjassot, Valencia, Spain, Email: ccanjuan@gmail.com |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
0952-4746 |
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Notes |
WOS:000428913900001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3552 |
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Author |
Esteve, R.; Toledo, J.F.; Herrero, V.; Simon, A.; Monrabal, F.; Alvarez, V.; Rodriguez, J.; Querol, M.; Ballester, F. |
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Title |
The Event Detection System in the NEXT-White Detector |
Type |
Journal Article |
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Year |
2021 |
Publication |
Sensors |
Abbreviated Journal |
Sensors |
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Volume |
21 |
Issue |
2 |
Pages |
673 - 18pp |
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Keywords |
xenon TPC; trigger concepts; data acquisition circuits; FPGA |
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Abstract |
This article describes the event detection system of the NEXT-White detector, a 5 kg high pressure xenon TPC with electroluminescent amplification, located in the Laboratorio Subterraneo de Canfranc (LSC), Spain. The detector is based on a plane of photomultipliers (PMTs) for energy measurements and a silicon photomultiplier (SiPM) tracking plane for offline topological event filtering. The event detection system, based on the SRS-ATCA data acquisition system developed in the framework of the CERN RD51 collaboration, has been designed to detect multiple events based on online PMT signal energy measurements and a coincidence-detection algorithm. Implemented on FPGA, the system has been successfully running and evolving during NEXT-White operation. The event detection system brings some relevant and new functionalities in the field. A distributed double event processor has been implemented to detect simultaneously two different types of events thus allowing simultaneous calibration and physics runs. This special feature provides constant monitoring of the detector conditions, being especially relevant to the lifetime and geometrical map computations which are needed to correct high-energy physics events. Other features, like primary scintillation event rejection, or a double buffer associated with the type of event being searched, help reduce the unnecessary data throughput thus minimizing dead time and improving trigger efficiency. |
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Address |
[Esteve Bosch, Raul; Toledo Alarcon, Jose F.; Herrero Bosch, Vicente; Alvarez Puerta, Vicente; Rodriguez Samaniego, Javier; Ballester Merelo, Francisco] Univ Politecn Valencia, CSIC, Inst Instrumentac Imagen Mol I3M, Ctr Mixto, Camino Vera S-N, Valencia 46022, Spain, Email: rauesbos@eln.upv.es; |
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Mdpi |
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English |
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Notes |
WOS:000611719600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4693 |
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