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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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Address |
[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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Conference |
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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 |
Garcia-Cases, F.; Perez-Calatayud, J.; Ballester, F.; Vijande, J.; Granero, D. |
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Title |
Peripheral dose around a mobile linac for intraoperative radiotherapy: radiation protection aspects |
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 |
4 |
Pages |
1393-1411 |
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Keywords |
Mobetron; mobile electron linear accelerator; radiotherapy intraoperative |
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Abstract |
The aim of this work is to analyse the scattered radiation produced by the mobile accelerator Mobetron 1000. To do so, detailed Monte Carlo simulations using two different codes, Penelope2008 and Geant4, were performed. Measurements were also done. To quantify the attenuation due to the internal structures, present in the accelerator head, on the scattered radiation produced, some of the main structural shielding in the Mobetron 1000 has been incorporated into the geometry simulation. Results are compared with measurements. Some discrepancies between the calculated and measured dose values were found. These differences can be traced back to the importance of the radiation component due to low energy scattered electrons. This encouraged us to perform additional calculations to separate the role played by this component. Ambient dose equivalent, H*(10), outside of the operating room (OR) has been evaluated using Geant4. H*(10) has been measured inside and outside the OR, being its values compatible with those reported in the literature once the low energy electron component is removed. With respect to the role played by neutrons, estimations of neutron H*(10) using Geant4 together with H*(10) measurements has been performed for the case of the 12 MeV electron beam. The values obtained agree with the experimental values existing in the literature, being much smaller than those registered in conventional accelerators. This study is a useful tool for the clinical user to investigate the radiation protection issues arising with the use of these accelerators in ORs without structural shielding. These results will also enable to better fix the maximum number of treatments that could be performed while insuring adequate radiological protection of workers and public in the hospital. |
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Address |
[Garcia-Cases, F.] Hosp Univ San Juan de Alicante, Serv Radiofis & Protecc Radiol, Alacant, Spain, Email: garcia_frad@gva.es |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
0952-4746 |
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Conference |
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Notes |
WOS:000448769200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
3784 |
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Author |
Richart, J.; Otal, A.; Rodriguez, S.; Nicolas, A.I.; DePiaggio, M.; Santos, M.; Vijande, J.; Ballester, F.; Perez-Calatayud, J. |
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Title |
A practical MRI-based reconstruction method for a new endocavitary and interstitial gynaecological template |
Type |
Journal Article |
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Year |
2015 |
Publication |
Journal of Contemporary Brachytherapy |
Abbreviated Journal |
J. Contemp. Brachytherapy |
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Volume |
7 |
Issue |
5 |
Pages |
407-414 |
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Keywords |
brachytherapy template; catheter reconstruction; gynecological template; interstitial implants |
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Abstract |
Purpose: There are perineal templates for interstitial implants such as MUPIT and Syed applicators. Their limitations are the intracavitary component deficit and the necessity to use computed tomography (CT) for treatment planning since both applicators are non-magnetic resonance imaging (MRI) compatibles. To overcome these problems, a new template named Template Benidorm (TB) has been recently developed. Titanium needles are usually reconstructed based on their own artifacts, mainly in T1-weighted sequence, using the void on the tip as the needle tip position. Nevertheless, patient tissues surrounding the needles present heterogeneities that complicate the accurate identification of these artifact patterns. The purpose of this work is to improve the titanium needle reconstruction uncertainty for the TB case using a simple method based on the free needle lengths and typical MRI pellets markers. Material and methods: The proposed procedure consists on the inclusion of three small A-vitamin pellets (hyper-intense on MRI images) compressed by both applicator plates defining the central plane of the plate's arrangement. The needles used are typically 20 cm in length. For each needle, two points are selected defining the straight line. From such line and the plane equations, the intersection can be obtained, and using the free length (knowing the offset distance), the coordinates of the needle tip can be obtained. The method is applied in both T1W and T2W acquisition sequences. To evaluate the inter-observer variation of the method, three implants of T1W and another three of T2W have been reconstructed by two different medical physicists with experience on these reconstructions. Results and conclusions: The differences observed in the positioning were significantly smaller than 1 mm in all cases. The presented algorithm also allows the use of only T2W sequence either for contouring or reconstruction purposes. The proposed method is robust and independent of the visibility of the artifact at the tip of the needle. |
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Address |
[Richart, Jose; Otal, Antonio; Rodriguez, Silvia; DePiaggio, Marina; Santos, Manuel; Perez-Calatayud, Jose] Benidorm Hosp, Dept Radiotherapy, Alicante, Spain, Email: fballest@uv.es |
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Corporate Author |
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Publisher |
Termedia Publishing House Ltd |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Volume |
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Edition |
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ISSN |
1689-832x |
ISBN |
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Conference |
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Notes |
WOS:000365247600012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
2476 |
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| Permanent link to this record |
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Author |
Candela-Juan, C.; Ballester, F.; Perez-Calatayud, J.; Vijande, J. |
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Title |
Assaying multiple I-125 seeds with the well-ionization chamber SourceCheck(4 Pi) 33005 and a new insert |
Type |
Journal Article |
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Year |
2015 |
Publication |
Journal of Contemporary Brachytherapy |
Abbreviated Journal |
J. Contemp. Brachytherapy |
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Volume |
7 |
Issue |
6 |
Pages |
492-496 |
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Keywords |
brachytherapy; insert; quality assurance; prostate; seeds; well chamber |
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Abstract |
Purpose: To provide a practical solution that can be adopted in clinical routine to fulfill the AAPM-ESTRO recommendations regarding quality assurance of seeds used in prostate permanent brachytherapy. The aim is to design a new insert for the well-ionization chamber SourceCheck(4 Pi) 33005 (PTW, Germany) that allows evaluating the mean air-kerma strength of up to ten I-125 seeds with one single measurement instead of measuring each seed individually. Material and methods: The material required is: a) the SourceCheck(4 Pi) 33005 well-ionization chamber provided with a PTW insert to measure the air-kerma strength S-K of one single seed at a time; b) a newly designed insert that accommodates ten seeds in one column, which allows measuring the mean S-K of the ten seeds in one single measurement; and c) a container with ten seeds from the same batch and class of the seeds used for the patient implant, and a set of nine non-radioactive seeds.The new insert is characterized by determining its calibration coefficient, used to convert the reading of the well-chamber when ten seeds are measured to their mean S-K. The proposed method is validated by comparing the mean S-K of the ten seeds obtained from the new insert with the individual measurement of S-K of each seed, evaluated with the PTW insert. Results: The ratio between the calibration coefficient of the new insert and the calibration coefficient of the PTW insert for the SourceCheck(4 Pi) 33005 is 1.135 +/- 0.007 (k = 1). The mean S-K of a set of ten seeds evaluated with this new system is in agreement with the mean value obtained from measuring independently the S-K of each seed. Conclusions: The new insert and procedure allow evaluating the mean S-K of ten seeds prior to the implant in a single measurement. The method is faster and more efficient from radiation protection point of view than measuring the individual S-K of each seed. |
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Address |
[Candela-Juan, Cristian; Perez-Calatayud, Jose] La Fe Univ, Dept Radiat Oncol, Phys Sect, E-46026 Valencia, Spain, Email: ccanjuan@gmail.com |
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Corporate Author |
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Publisher |
Termedia Publishing House Ltd |
Place of Publication |
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Language |
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 |
1689-832x |
ISBN |
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Conference |
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Notes |
WOS:000368381300010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
2533 |
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Author |
Vijande, J.; Carmona, V.; Lliso, F.; Ballester, F.; Perez-Calatayud, J. |
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Title |
An efficient component of the redundancy calibration program to ensure equipment stability by assaying HDR Ir-192 sources at the time of replacement |
Type |
Journal Article |
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Year |
2024 |
Publication |
Journal of Applied Clinical Medical Physics |
Abbreviated Journal |
J. Appl. Clin. Med. Phys |
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Volume |
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Issue |
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Pages |
5pp |
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Keywords |
brachytherapy |
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Abstract |
BackgroundBrachytherapy (BT) treatments involving temporary high-dose rate (HDR) sources are extensively employed in clinical practice. Ensuring the consistency of all measurement equipment at the hospital level is crucial, requiring a robust redundancy and consistency program. This enables the institution to verify the stability of the dosimetry system over time.PurposeTo describe, justify, and analyze a component of the redundancy program of the calibration protocols followed by the Radiotherapy Department of the Hospital Universitari i Polit & egrave;cnic La Fe (Val & egrave;ncia, Spain) during the last 10 years for the case of HDR BT as an additional component to ensure long term stability of the measurement equipment.MethodsAt the time the HDR BT source is replaced, its Air Kerma Strength (SK) is measured. By comparing this value with the one obtained at the time of installation (corrected by decay), a clear determination of the stability of the measurement equipment can be performed.ResultsDifference between SK,vendor and SK,hosp as a function of the measurement date is reported for a 10 years' period. All measurements are well within the +/- 3% tolerance level recommended in current international guidelines. Percentage differences of SK,hosp values at the time of replacement compared to SK,hosp ones at the time when the source was installed are within the +/- 0.5% range, reflecting oscillations around a null deviation.ConclusionsThe method proposed allows any hospital to ensure a redundancy component of the long-term stability of all equipment involved in BT measurements in a very simple and time efficient manner. Additionally, it enables the hospital to maintain a detailed log of historical differences, facilitating the identification and correction of potential systematic deviations over time. |
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Address |
[Vijande, Javier; Ballester, Facundo] Univ Valencia UV, Dept Fis Atom Mol & Nucl, Burjassot, Spain, Email: Javier.Vijande@uv.es |
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Corporate Author |
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Thesis |
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Publisher |
Wiley |
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 |
1526-9914 |
ISBN |
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Area |
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Conference |
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Notes |
WOS:001306138000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
6250 |
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