Antonio Lopez Medina - Academia.edu (original) (raw)
Papers by Antonio Lopez Medina
Physica Medica, 2022
Training, educating, and fostering of young professionals are key requisites for the progress of ... more Training, educating, and fostering of young professionals are key requisites for the progress of any profession. The young medical physicists (MPs) of today are the medical physics professionals and leaders of tomorrow. It is, therefore, essential that they learn to work collectively and in a coordinated manner at both national and European levels at an early stage in their career. In view of this, EFOMP is planning to create a special interest group (SIG) encompassing early career MPs from across Europe. Methods: A survey was developed by EFOMP and circulated to all National Member Organisations (NMOs) to gather information on the status of early career groups in their respective societies and on the interest to partake in such group within the Federation. Results: Of the 36 NMOs that are part of EFOMP, 32 responded to the survey. Only 9 NMOs have established early career MPs groups within their NMOs, while the remaining countries are either considering setting up young MPs groups in the future (15 NMOs) or do not show such interest (8 NMOs). Of all responders, 59% expressed interest in the creation of the EFOMP SIG, 34% remained neutral towards this issue by not answering the question and for two NMOs the SIG idea had no appeal. Conclusion: Most NMOs showed interest in the creation of an early career MPs group within EFOMP and offered constructive feedbacks on the roles they envisage for the group. EFOMP will use and implement this information when establishing the special interest group.
Physica Medica, 2021
ESTRO-EFOMP intend to update the core curriculum (CC) for education and training of medical physi... more ESTRO-EFOMP intend to update the core curriculum (CC) for education and training of medical physicists in radiotherapy in line with the European Commission (EC) guidelines on Medical Physics Experts (MPE), the CanMEDS methodology and recent developments in radiotherapy. As input, a survey of the current structure of radiotherapy MPE national training schemes (NTS) in Europe was carried out. Methods: A 35-question survey was sent to all European medical physics national societies (NS) with a focus on existence of an NTS, its format and duration, required entry-level education, and financial support for trainees. Results: Twenty-six of 36 NS responded. Twenty had an NTS. Minimum required pre-training education varied from BSc in physics or related sciences (5/2) to MSc in medical physics, physics or related sciences (6/5/2) with 50-210 ECTS in fundamental physics and mathematics. The training period varied from 1 to 5 years (median 3 years with 50% dedicated to radiotherapy). The ratio of time spent on university lectures versus hospital training was most commonly 25%/75%. In 14 of 20 countries with an NTS, a research project was mandatory. Residents were paid in 17 of 20 countries. The recognition was mostly obtained by examination. Medical physics is recognised as a healthcare profession in 19 of 26 countries.
![Research paper thumbnail of Occupational radiation exposure assessment during the management of [68Ga]Ga-DOTA-TOC](https://attachments.academia-assets.com/113137520/thumbnails/1.jpg)
](EJNMMI Physics, Oct 29, 2022
Background: Since it was first approved in Europe in 2016, the gallium-68 (68 Ga) radiopharmaceut... more Background: Since it was first approved in Europe in 2016, the gallium-68 (68 Ga) radiopharmaceutical [ 68 Ga]Ga-DOTA-TOC has been widely used for imaging of somatostatin receptor (SSTR) positive tumours using positron emission tomography-computed tomography (PET/CT). Significant patient benefits have been reported, so its use is rapidly increasing. However, few studies have been published regarding occupational doses to nuclear medicine personnel handling this radiopharmaceutical, despite its manual usage at low distances from the skin and the beta-emission decay scheme, which may result in an increased absorbed dose to their hands. In this context, this study aims to analyse the occupational exposure during the administration of [ 68 Ga] Ga-DOTA-TOC for PET/CT imaging. For this purpose, extremity, eye lens and wholebody dosimetry in terms of Hp(0.07), Hp(3) and Hp(10), respectively, was conducted on six workers with both thermoluminescent dosimeters, and personal electronic dosimeters. Results: The non-dominant hand is more exposed to radiation than the dominant hand, with the thumb and the index fingertip being the most exposed sites on this hand. Qualitative analysis showed that when no shielding is used during injection, doses increase significantly more in the dominant than in the non-dominant hand, so the use of shielding is strongly recommended. While wrist dosimeters may significantly underestimate doses to the hands, placing a ring dosimeter at the base of the ring or middle finger of the non-dominant hand may give a valuable estimation of maximum doses to the hands if at least a correction factor of 5 is applied. Personal equivalent doses for the eyes did not result in measurable values (i.e., above the lowest detection limit) for almost all workers. The extrapolated annual dose estimations showed that there is compliance with the annual dose limits during management of [ 68 Ga] Ga-DOTA-TOC for diagnostics with PET in the hospital included in this study. Conclusions: Imaging with [ 68 Ga]Ga-DOTA-TOC is a safe process for the workers performing the administration of the radiopharmaceutical, including intravenous injection to the patient and the pre-and post-activity control, as it is highly unlikely that annual dose limits will be exceeded if good working practices and shielding are used.
![Research paper thumbnail of Radiation Exposure Assessment of Nuclear Medicine Staff Administering [177Lu]Lu-DOTA-TATE with Active and Passive Dosimetry](https://attachments.academia-assets.com/113137518/thumbnails/1.jpg)
](Research Square (Research Square), Jul 13, 2023
Research Square (Research Square), May 17, 2023
Radiotherapy and Oncology, May 1, 2023
Radiotherapy and Oncology, Apr 1, 2019
Purpose or Objective There is a steady rise in the use of Stereotactic Body RadioTherapy (SBRT) i... more Purpose or Objective There is a steady rise in the use of Stereotactic Body RadioTherapy (SBRT) in oligometastatic disease (OMD). Besides a positive impact on patients' outcome, this may generate important financial consequences for radiotherapy budgets. Awaiting more clinical evidence, the Belgian compulsory health insurance system initiated a coverage with evidence development (CED) project for innovative radiotherapy, including SBRT, in 2011. Consequently, a provisional financing to treat OMD with SBRT was available in Belgium from 2013 onwards. While analysis of the clinical and technical data captured between 9-2013 and 12-2017 is ongoing and inclusion in the formal reimbursement system pending, a costcalculation and budget impact analysis (BIA) was carried out. Material and Methods Using the CED data, the uptake of SBRT in patients with OMD in Belgium between 2013 and 2017 was reviewed. Based on these data, predictive growth scenarios for future uptake were developed. The cost of an SBRT treatment in the OMD setting in Belgium was calculated using the Health Economics in Radiation Oncology Time-Driven Activity-Based Costing (HERO TD-ABC) model developed by ESTRO, alimented with national data on resources, treatments and operational parameters. Combining all this information, the future impact of this novel treatment indication on the radiotherapy budget in Belgium was evaluated. Results The CED data showed a large increase in number of OMD treated with SBRT in Belgium: from 59 in 2013 to 459 in 2017. Based on this, three growth scenarios for uptake were developed: scenario 1, predicting a further linear increase; scenario 2, only accounting for demographic shift; and an 'intermediate' scenario 3 with linear increase for two more years, then plateauing to the demographic trends (Figure 1).
Background Selective internal radiation therapy (SIRT) with 90Y radioembolization aims to selecti... more Background Selective internal radiation therapy (SIRT) with 90Y radioembolization aims to selectively irradiate liver tumors by administering radioactive microspheres under the theragnostic assumption that the pre-therapy injection of 99mTc labeled macro-aggregated albumin (99mTc-MAA) provides an estimation of the 90Y microspheres biodistribution, which is not always the case. Due to the growing interest in theragnostic dosimetry for personalized radionuclide therapy, a robust relationship between the delivered and pre-treatment radiation doses is required. In this work, we aim to investigate the predictive value of absorbed dose metrics calculated from 99mTc-MAA (simulation) compared to those obtained from 90Y post-therapy SPECT/CT.Results A total of 79 patients were analyzed. Pre- and post-therapy 3D-voxel dosimetry was calculated on 99mTc-MAA and 90Y SPECT/CT, respectively, based on Local Deposition Method (LDM). Mean absorbed dose, tumor-to-normal ratio, and dose distribution in...
IFMBE Proceedings, 2018
Intra-tumor variability of oxygenation and clonogenic cell density causes tumor non-uniform spati... more Intra-tumor variability of oxygenation and clonogenic cell density causes tumor non-uniform spatial response to radiation. Strategies like dose redistribution/boosting, whose impact should be quantified in terms of tumor control probability (TCP), have been proposed to improve treatment outcome. In 1999, Sanchez-Nieto et al. developed a tool to evaluate the impact of dose distribution inhomogeneities, compared to a reference homogeneous dose distribution, in terms of TCP. DVH data were used to calculate the so-called ∆TCP, defined as the difference in TCP arising from dose variations in individual DVH-bins. In this work, we develop an open source tool to calculate volumetric ∆TCP and evaluate the impact on TCP of: (i) Spatial dose distribution variations with respect to a reference dose; (ii) Spatial radiosensitivity variations with respect to a reference radiosensitivity; (iii) Simultaneous variation in dose distribution and radiosensitivity. ∆TCP calculations can be evaluated voxel-by-voxel, or in a user defined subvolume basis. The tool capabilities are shown with 2 examples of H&N RT treatments and subvolume contours data providing information about tumor oxygenation status. ΔTCP values are computed for a homogeneous dose to a well oxygenated tumor volume (with a homogeneous 5% vascular fraction), as reference condition, with respect to the same dose now considering 3 oxygenation levels and 3 cell density values (104, 106 and 107 cells/mm3, respectively). ΔTCP values are also computed for the comparison of a homogenous dose distribution vs a redistributed dose distribution delivered to the non-homogeneous tumor.
The Lancet Oncology, 2020
Reimbursement is a key factor in defining which resources are made available to ensure quality, e... more Reimbursement is a key factor in defining which resources are made available to ensure quality, efficiency, availability, and access to specific health-care interventions. This Policy Review assesses publicly funded radiotherapy reimbursement systems in Europe. We did a survey of the national societies of radiation oncology in Europe, focusing on the general features and global structure of the reimbursement system, the coverage scope, and level for typical indications. The annual expenditure covering radiotherapy in each country was also collected. Most countries have a predominantly budgetary-based system. Variability was the major finding, both in the components of the treatment considered for reimbursement, and in the fees paid for specific treatment techniques, fractionations, and indications. Annual expenses for radiotherapy, including capital investment, available in 12 countries, represented between 4•3% and 12•3% (average 7•8%) of the cancer care budget. Although an essential pillar in multidisciplinary oncology, radiotherapy is an inexpensive modality with a modest contribution to total cancer care costs. Scientific societies and policy makers across Europe need to discuss new strategies for reimbursement, combining flexibility with incentives to improve productivity and quality, allowing radiation oncology services to follow evolving evidence.
Revista de Neurología, 2008
ABSTRACT Introducción. Las malformaciones arteriovenosas son comunicaciones anómalas entre arteri... more ABSTRACT Introducción. Las malformaciones arteriovenosas son comunicaciones anómalas entre arterias y venas. El tratamiento puede realizarse mediante cirugía, embolización y/o radiocirugía. Objetivo. Evaluar la influencia de la radiocirugía sobre el riesgo de sangrado y los factores relacionados con éste. Pacientes y métodos. Estudio retrospectivo de 79 pacientes tratados con acelerador lineal de 6 MV. Se recogieron parámetros clínicos, morfológicos y dosimétricos, analizando estadísticamente su relación con el sangrado durante el período de latencia. Resultados. La edad media fue de 33,7 años, y el 56% fueron mujeres. El volumen medio fue de 6,16 cm3. El 52,6% sangró antes del tratamiento. El 25% había sido embolizado y el 7,6% había recibido radiocirugía previamente. Seis pacientes sufrieron hemorragia tras el tratamiento. Sangró el 21% de los embolizados, frente al 3,6% de los no embolizados (p = 0,02). Entre los tratados con más de una radiocirugía sangró el 33,3%, y sólo el 5,7% si se trataron una sola vez (p = 0,02). Sangró el 28,6% de las lesiones mayores de 10 cm3 y el 3,2% de las menores (p < 0,01). Sangró el 16,1% si recibieron menos de 17 Gy, y el 2,22% si recibieron 17 o más (p < 0,01). Todas las hemorragias se produjeron en tratamientos con más de un isocentro (p < 0,01) y con índice de homogeneidad más alto (p < 0,01). Conclusiones. La radiocirugía no modifica el riesgo de sangrado. Los factores asociados con mayores porcentajes de hemorragia se relacionan también con peores resultados de cierre y períodos de latencia más prolongados.
Radiotherapy and Oncology, 2011
Radiotherapy and Oncology, 2011
Contemporary brachytherapy TPS employing advanced dose calculation algorithms have begun phasing ... more Contemporary brachytherapy TPS employing advanced dose calculation algorithms have begun phasing in to clinical practice. This marks a significant departure from the simplified assumptions of conventional TG-43 based TPS dosimetry. New methods are therefore required to affirm the dosimetric accuracy improvement of these TPS. These methods should be readily available and suitable for use in the clinic in order to meet regulatory demands for commissioning and enhance uniform transition from conventional to contemporary planning practice. Materials: A set of virtual phantoms were prepared in DICOM CT image format. Four phantoms comprised homogeneous water geometries appropriate for checking automatic catheter reconstruction, source dosimetry accuracy in TG-43 conditions, altered scatter conditions and the presence of shielded applicators. Two more phantoms were prepared to assess TPS accuracy in inhomogeneous geometries, as well as the efficiency of auto-contouring, volumetric and DVH calculation TPS features. These were imported to the Oncentra v3.3 and Brachyvision v10.0 TPS. TG-43 results from both TPS and results obtained using the Acuros grid based Boltzmann solver of the latter TPS were exported in DICOM-RT format. Reference dose distributions were obtained using MC simulations for the VS2000 and microSelectron-v2 HDR 192 Ir sources. MC and TPS comparison results were performed using custom made tools where necessary. Results: MC and TPS comparison results in homogeneous phantoms yielded very good agreement for both TPS with noticeable differences observed at a limited number of points. Although these differences are of minor clinical significance, they could easily go undetected when using conventional tools that perform comparison at user selected points. Both treatment planning systems were found to perform satisfactorily in terms of catheter reconstruction, contouring and DVH calculations. Comparisons also confirmed the ability of the Brachyvision TPS to accurately account for scatter conditions, applicator and patient inhomogeneities. Differences beyond the acceptance criteria, which were set equal to the statistical uncertainty of MC, were spatially limited in agreement with similar findings in the literature. Conclusions: The tools and procedure proposed in this work are shown appropriate for a thorough QA test of dosimetric performance and other basic features of both conventional and contemporary brachytherapy TPS.
Reports of Practical Oncology & Radiotherapy, 2013
In the last years, there were big steps in the treatment of head and neck cancer (HNC), but local... more In the last years, there were big steps in the treatment of head and neck cancer (HNC), but local relapse rates are still very high. In our hospital, we started a research project (2012-2014) focused on quantifying tumour response of HNC patients (#50) by serial PET/CT and MRI (Apparent Diffusion Coefficient-ADC). The aim of this video is to present our methodology, our preliminary results (#5), and illustrate patient's experiences. For this study we select "oropharynx T3 and T4" patients. The standard dose to the PTV is 66 Gy by IMRT (S&S). The imaging protocol will be as follows; pre-treatment: MRI study (diffusion-weighted MR) and PET/CT study (18F-FDG). First control (10-20 Gy): MRI diffusion study. Second control (20-50 Gy): MRI diffusion study. Three months after the treatment: PET/CT and MRI diffusion studies. For all the studies the patient is positioned using the RT immobilisation devices to ease image registration. For each patient and each set of images the ADC values, SUV, dose and HU per voxel were recorded of each volume. An interview to patients was performed and they can explain freely their experiences. The average initial ADC value obtained for tumour and node volumes was 1.29 × 10 −3 mm 2 /s. The relationship of ADC vs dose is always a rising function. Controls performed three months after treatment shows no local relapses in the only ended patient. ADC can be used not only for treatment assessment, but also for quantification of tumour response voxel by voxel. Even more, the joint use of MRI and PET/CT can be useful for delimiting the hypoxic areas, due to glucose consumption enhancement by Pasteur effect in hypoxic cells. Although most participating patients complain of lost time, all of them will participate again. Supported by ISCIII Grant PI11/02035.
Medical Physics, 2009
Purpose: Modern radiotherapy uses complex treatments that necessitate more complex quality assura... more Purpose: Modern radiotherapy uses complex treatments that necessitate more complex quality assurance procedures. As a continuous medium, GafChromic EBT films offer suitable features for such verification. However, its sensitometric curve is not fully understood in terms of classical theoretical models. In fact, measured optical densities and those predicted by the classical models differ significantly. This difference increases systematically with wider dose ranges. Thus, achieving the accuracy required for intensity-modulated radiotherapy ͑IMRT͒ by classical methods is not possible, plecluding their use. As a result, experimental parametrizations, such as polynomial fits, are replacing phenomenological expressions in modern investigations. This article focuses on identifying new theoretical ways to describe sensitometric curves and on evaluating the quality of fit for experimental data based on four proposed models. Methods: A whole mathematical formalism starting with a geometrical version of the classical theory is used to develop new expressions for the sensitometric curves. General results from the percolation theory are also used. A flat-bed-scanner-based method was chosen for the film analysis. Different tests were performed, such as consistency of the numeric results for the proposed model and double examination using data from independent researchers. Results: Results show that the percolation-theory-based model provides the best theoretical explanation for the sensitometric behavior of GafChromic films. The different sizes of active centers or monomer crystals of the film are the basis of this model, allowing acquisition of information about the internal structure of the films. Values for the mean size of the active centers were obtained in accordance with technical specifications. In this model, the dynamics of the interaction between the active centers of GafChromic film and radiation is also characterized by means of its interaction cross-section value. Conclusions: The percolation model fulfills the accuracy requirements for quality-control procedures when large ranges of doses are used and offers a physical explanation for the film response.
Medical Physics, 2012
Currently, quality control (QC) for each IMRT treatment is performed by dose distribution measure... more Currently, quality control (QC) for each IMRT treatment is performed by dose distribution measurements. These techniques are very time-consuming and require long accelerator downtime. QC could be only based in verification of monitor units and dose distributions, if precise control of MLC is carried out. In such a manner, the e-IMRT platform (http://eimrt.cesga.es/) is a remote distributed computing tool, which allows comparison between the dose distributions calculated by a TPS and those calculated by Monte Carlo (MC). Previously, our linear accelerator (Oncor Impression, Siemens) was commissioned. For this purpose, comparison of experimental and MC simulated data was carried out. Several IMRT treatments plans were calculated in superposition algorithm (TPS Xio®CMS 4.60.00) and used as input data for the e-IMRT platform. These treatment plans were previously verified employing a 2D array MapCheckTM, Sun Nuclear. The gamma index (3%, 3mm) was used for validating results. The platform displays calculated doses using MC, also gamma map (in the CT images, not only statistical data) and histogram shown in Figures 1a), b) and d). The gamma map illustrates the differences between the input and calculated doses. According to the legend in Figure 1 d), these differences correspond to less than 1%. Results show good agreement between the doses calculated by TPS and those computed by e-IMRT platform. If a rigorous quality control is established for MLC and optimisation criteria (number of gantry angles, minimum segment size, levels of intensity for fluency map) are used. Then, QC for IMRT standard treatment plans would be only based on the verification of monitor units and dose distributions using e-IMRT II.This work has been funded by the Xunta de Galicia, Project R&D Grant 09SIN007CT. We would like to thank Centro de SupercomputaciÃ3 n de Galicia for the computational resources and support.
Physica Medica, 2022
Training, educating, and fostering of young professionals are key requisites for the progress of ... more Training, educating, and fostering of young professionals are key requisites for the progress of any profession. The young medical physicists (MPs) of today are the medical physics professionals and leaders of tomorrow. It is, therefore, essential that they learn to work collectively and in a coordinated manner at both national and European levels at an early stage in their career. In view of this, EFOMP is planning to create a special interest group (SIG) encompassing early career MPs from across Europe. Methods: A survey was developed by EFOMP and circulated to all National Member Organisations (NMOs) to gather information on the status of early career groups in their respective societies and on the interest to partake in such group within the Federation. Results: Of the 36 NMOs that are part of EFOMP, 32 responded to the survey. Only 9 NMOs have established early career MPs groups within their NMOs, while the remaining countries are either considering setting up young MPs groups in the future (15 NMOs) or do not show such interest (8 NMOs). Of all responders, 59% expressed interest in the creation of the EFOMP SIG, 34% remained neutral towards this issue by not answering the question and for two NMOs the SIG idea had no appeal. Conclusion: Most NMOs showed interest in the creation of an early career MPs group within EFOMP and offered constructive feedbacks on the roles they envisage for the group. EFOMP will use and implement this information when establishing the special interest group.
Physica Medica, 2021
ESTRO-EFOMP intend to update the core curriculum (CC) for education and training of medical physi... more ESTRO-EFOMP intend to update the core curriculum (CC) for education and training of medical physicists in radiotherapy in line with the European Commission (EC) guidelines on Medical Physics Experts (MPE), the CanMEDS methodology and recent developments in radiotherapy. As input, a survey of the current structure of radiotherapy MPE national training schemes (NTS) in Europe was carried out. Methods: A 35-question survey was sent to all European medical physics national societies (NS) with a focus on existence of an NTS, its format and duration, required entry-level education, and financial support for trainees. Results: Twenty-six of 36 NS responded. Twenty had an NTS. Minimum required pre-training education varied from BSc in physics or related sciences (5/2) to MSc in medical physics, physics or related sciences (6/5/2) with 50-210 ECTS in fundamental physics and mathematics. The training period varied from 1 to 5 years (median 3 years with 50% dedicated to radiotherapy). The ratio of time spent on university lectures versus hospital training was most commonly 25%/75%. In 14 of 20 countries with an NTS, a research project was mandatory. Residents were paid in 17 of 20 countries. The recognition was mostly obtained by examination. Medical physics is recognised as a healthcare profession in 19 of 26 countries.
EJNMMI Physics, Oct 29, 2022
Background: Since it was first approved in Europe in 2016, the gallium-68 (68 Ga) radiopharmaceut... more Background: Since it was first approved in Europe in 2016, the gallium-68 (68 Ga) radiopharmaceutical [ 68 Ga]Ga-DOTA-TOC has been widely used for imaging of somatostatin receptor (SSTR) positive tumours using positron emission tomography-computed tomography (PET/CT). Significant patient benefits have been reported, so its use is rapidly increasing. However, few studies have been published regarding occupational doses to nuclear medicine personnel handling this radiopharmaceutical, despite its manual usage at low distances from the skin and the beta-emission decay scheme, which may result in an increased absorbed dose to their hands. In this context, this study aims to analyse the occupational exposure during the administration of [ 68 Ga] Ga-DOTA-TOC for PET/CT imaging. For this purpose, extremity, eye lens and wholebody dosimetry in terms of Hp(0.07), Hp(3) and Hp(10), respectively, was conducted on six workers with both thermoluminescent dosimeters, and personal electronic dosimeters. Results: The non-dominant hand is more exposed to radiation than the dominant hand, with the thumb and the index fingertip being the most exposed sites on this hand. Qualitative analysis showed that when no shielding is used during injection, doses increase significantly more in the dominant than in the non-dominant hand, so the use of shielding is strongly recommended. While wrist dosimeters may significantly underestimate doses to the hands, placing a ring dosimeter at the base of the ring or middle finger of the non-dominant hand may give a valuable estimation of maximum doses to the hands if at least a correction factor of 5 is applied. Personal equivalent doses for the eyes did not result in measurable values (i.e., above the lowest detection limit) for almost all workers. The extrapolated annual dose estimations showed that there is compliance with the annual dose limits during management of [ 68 Ga] Ga-DOTA-TOC for diagnostics with PET in the hospital included in this study. Conclusions: Imaging with [ 68 Ga]Ga-DOTA-TOC is a safe process for the workers performing the administration of the radiopharmaceutical, including intravenous injection to the patient and the pre-and post-activity control, as it is highly unlikely that annual dose limits will be exceeded if good working practices and shielding are used.
Research Square (Research Square), Jul 13, 2023
Research Square (Research Square), May 17, 2023
Radiotherapy and Oncology, May 1, 2023
Radiotherapy and Oncology, Apr 1, 2019
Purpose or Objective There is a steady rise in the use of Stereotactic Body RadioTherapy (SBRT) i... more Purpose or Objective There is a steady rise in the use of Stereotactic Body RadioTherapy (SBRT) in oligometastatic disease (OMD). Besides a positive impact on patients' outcome, this may generate important financial consequences for radiotherapy budgets. Awaiting more clinical evidence, the Belgian compulsory health insurance system initiated a coverage with evidence development (CED) project for innovative radiotherapy, including SBRT, in 2011. Consequently, a provisional financing to treat OMD with SBRT was available in Belgium from 2013 onwards. While analysis of the clinical and technical data captured between 9-2013 and 12-2017 is ongoing and inclusion in the formal reimbursement system pending, a costcalculation and budget impact analysis (BIA) was carried out. Material and Methods Using the CED data, the uptake of SBRT in patients with OMD in Belgium between 2013 and 2017 was reviewed. Based on these data, predictive growth scenarios for future uptake were developed. The cost of an SBRT treatment in the OMD setting in Belgium was calculated using the Health Economics in Radiation Oncology Time-Driven Activity-Based Costing (HERO TD-ABC) model developed by ESTRO, alimented with national data on resources, treatments and operational parameters. Combining all this information, the future impact of this novel treatment indication on the radiotherapy budget in Belgium was evaluated. Results The CED data showed a large increase in number of OMD treated with SBRT in Belgium: from 59 in 2013 to 459 in 2017. Based on this, three growth scenarios for uptake were developed: scenario 1, predicting a further linear increase; scenario 2, only accounting for demographic shift; and an 'intermediate' scenario 3 with linear increase for two more years, then plateauing to the demographic trends (Figure 1).
Background Selective internal radiation therapy (SIRT) with 90Y radioembolization aims to selecti... more Background Selective internal radiation therapy (SIRT) with 90Y radioembolization aims to selectively irradiate liver tumors by administering radioactive microspheres under the theragnostic assumption that the pre-therapy injection of 99mTc labeled macro-aggregated albumin (99mTc-MAA) provides an estimation of the 90Y microspheres biodistribution, which is not always the case. Due to the growing interest in theragnostic dosimetry for personalized radionuclide therapy, a robust relationship between the delivered and pre-treatment radiation doses is required. In this work, we aim to investigate the predictive value of absorbed dose metrics calculated from 99mTc-MAA (simulation) compared to those obtained from 90Y post-therapy SPECT/CT.Results A total of 79 patients were analyzed. Pre- and post-therapy 3D-voxel dosimetry was calculated on 99mTc-MAA and 90Y SPECT/CT, respectively, based on Local Deposition Method (LDM). Mean absorbed dose, tumor-to-normal ratio, and dose distribution in...
IFMBE Proceedings, 2018
Intra-tumor variability of oxygenation and clonogenic cell density causes tumor non-uniform spati... more Intra-tumor variability of oxygenation and clonogenic cell density causes tumor non-uniform spatial response to radiation. Strategies like dose redistribution/boosting, whose impact should be quantified in terms of tumor control probability (TCP), have been proposed to improve treatment outcome. In 1999, Sanchez-Nieto et al. developed a tool to evaluate the impact of dose distribution inhomogeneities, compared to a reference homogeneous dose distribution, in terms of TCP. DVH data were used to calculate the so-called ∆TCP, defined as the difference in TCP arising from dose variations in individual DVH-bins. In this work, we develop an open source tool to calculate volumetric ∆TCP and evaluate the impact on TCP of: (i) Spatial dose distribution variations with respect to a reference dose; (ii) Spatial radiosensitivity variations with respect to a reference radiosensitivity; (iii) Simultaneous variation in dose distribution and radiosensitivity. ∆TCP calculations can be evaluated voxel-by-voxel, or in a user defined subvolume basis. The tool capabilities are shown with 2 examples of H&N RT treatments and subvolume contours data providing information about tumor oxygenation status. ΔTCP values are computed for a homogeneous dose to a well oxygenated tumor volume (with a homogeneous 5% vascular fraction), as reference condition, with respect to the same dose now considering 3 oxygenation levels and 3 cell density values (104, 106 and 107 cells/mm3, respectively). ΔTCP values are also computed for the comparison of a homogenous dose distribution vs a redistributed dose distribution delivered to the non-homogeneous tumor.
The Lancet Oncology, 2020
Reimbursement is a key factor in defining which resources are made available to ensure quality, e... more Reimbursement is a key factor in defining which resources are made available to ensure quality, efficiency, availability, and access to specific health-care interventions. This Policy Review assesses publicly funded radiotherapy reimbursement systems in Europe. We did a survey of the national societies of radiation oncology in Europe, focusing on the general features and global structure of the reimbursement system, the coverage scope, and level for typical indications. The annual expenditure covering radiotherapy in each country was also collected. Most countries have a predominantly budgetary-based system. Variability was the major finding, both in the components of the treatment considered for reimbursement, and in the fees paid for specific treatment techniques, fractionations, and indications. Annual expenses for radiotherapy, including capital investment, available in 12 countries, represented between 4•3% and 12•3% (average 7•8%) of the cancer care budget. Although an essential pillar in multidisciplinary oncology, radiotherapy is an inexpensive modality with a modest contribution to total cancer care costs. Scientific societies and policy makers across Europe need to discuss new strategies for reimbursement, combining flexibility with incentives to improve productivity and quality, allowing radiation oncology services to follow evolving evidence.
Revista de Neurología, 2008
ABSTRACT Introducción. Las malformaciones arteriovenosas son comunicaciones anómalas entre arteri... more ABSTRACT Introducción. Las malformaciones arteriovenosas son comunicaciones anómalas entre arterias y venas. El tratamiento puede realizarse mediante cirugía, embolización y/o radiocirugía. Objetivo. Evaluar la influencia de la radiocirugía sobre el riesgo de sangrado y los factores relacionados con éste. Pacientes y métodos. Estudio retrospectivo de 79 pacientes tratados con acelerador lineal de 6 MV. Se recogieron parámetros clínicos, morfológicos y dosimétricos, analizando estadísticamente su relación con el sangrado durante el período de latencia. Resultados. La edad media fue de 33,7 años, y el 56% fueron mujeres. El volumen medio fue de 6,16 cm3. El 52,6% sangró antes del tratamiento. El 25% había sido embolizado y el 7,6% había recibido radiocirugía previamente. Seis pacientes sufrieron hemorragia tras el tratamiento. Sangró el 21% de los embolizados, frente al 3,6% de los no embolizados (p = 0,02). Entre los tratados con más de una radiocirugía sangró el 33,3%, y sólo el 5,7% si se trataron una sola vez (p = 0,02). Sangró el 28,6% de las lesiones mayores de 10 cm3 y el 3,2% de las menores (p < 0,01). Sangró el 16,1% si recibieron menos de 17 Gy, y el 2,22% si recibieron 17 o más (p < 0,01). Todas las hemorragias se produjeron en tratamientos con más de un isocentro (p < 0,01) y con índice de homogeneidad más alto (p < 0,01). Conclusiones. La radiocirugía no modifica el riesgo de sangrado. Los factores asociados con mayores porcentajes de hemorragia se relacionan también con peores resultados de cierre y períodos de latencia más prolongados.
Radiotherapy and Oncology, 2011
Radiotherapy and Oncology, 2011
Contemporary brachytherapy TPS employing advanced dose calculation algorithms have begun phasing ... more Contemporary brachytherapy TPS employing advanced dose calculation algorithms have begun phasing in to clinical practice. This marks a significant departure from the simplified assumptions of conventional TG-43 based TPS dosimetry. New methods are therefore required to affirm the dosimetric accuracy improvement of these TPS. These methods should be readily available and suitable for use in the clinic in order to meet regulatory demands for commissioning and enhance uniform transition from conventional to contemporary planning practice. Materials: A set of virtual phantoms were prepared in DICOM CT image format. Four phantoms comprised homogeneous water geometries appropriate for checking automatic catheter reconstruction, source dosimetry accuracy in TG-43 conditions, altered scatter conditions and the presence of shielded applicators. Two more phantoms were prepared to assess TPS accuracy in inhomogeneous geometries, as well as the efficiency of auto-contouring, volumetric and DVH calculation TPS features. These were imported to the Oncentra v3.3 and Brachyvision v10.0 TPS. TG-43 results from both TPS and results obtained using the Acuros grid based Boltzmann solver of the latter TPS were exported in DICOM-RT format. Reference dose distributions were obtained using MC simulations for the VS2000 and microSelectron-v2 HDR 192 Ir sources. MC and TPS comparison results were performed using custom made tools where necessary. Results: MC and TPS comparison results in homogeneous phantoms yielded very good agreement for both TPS with noticeable differences observed at a limited number of points. Although these differences are of minor clinical significance, they could easily go undetected when using conventional tools that perform comparison at user selected points. Both treatment planning systems were found to perform satisfactorily in terms of catheter reconstruction, contouring and DVH calculations. Comparisons also confirmed the ability of the Brachyvision TPS to accurately account for scatter conditions, applicator and patient inhomogeneities. Differences beyond the acceptance criteria, which were set equal to the statistical uncertainty of MC, were spatially limited in agreement with similar findings in the literature. Conclusions: The tools and procedure proposed in this work are shown appropriate for a thorough QA test of dosimetric performance and other basic features of both conventional and contemporary brachytherapy TPS.
Reports of Practical Oncology & Radiotherapy, 2013
In the last years, there were big steps in the treatment of head and neck cancer (HNC), but local... more In the last years, there were big steps in the treatment of head and neck cancer (HNC), but local relapse rates are still very high. In our hospital, we started a research project (2012-2014) focused on quantifying tumour response of HNC patients (#50) by serial PET/CT and MRI (Apparent Diffusion Coefficient-ADC). The aim of this video is to present our methodology, our preliminary results (#5), and illustrate patient's experiences. For this study we select "oropharynx T3 and T4" patients. The standard dose to the PTV is 66 Gy by IMRT (S&S). The imaging protocol will be as follows; pre-treatment: MRI study (diffusion-weighted MR) and PET/CT study (18F-FDG). First control (10-20 Gy): MRI diffusion study. Second control (20-50 Gy): MRI diffusion study. Three months after the treatment: PET/CT and MRI diffusion studies. For all the studies the patient is positioned using the RT immobilisation devices to ease image registration. For each patient and each set of images the ADC values, SUV, dose and HU per voxel were recorded of each volume. An interview to patients was performed and they can explain freely their experiences. The average initial ADC value obtained for tumour and node volumes was 1.29 × 10 −3 mm 2 /s. The relationship of ADC vs dose is always a rising function. Controls performed three months after treatment shows no local relapses in the only ended patient. ADC can be used not only for treatment assessment, but also for quantification of tumour response voxel by voxel. Even more, the joint use of MRI and PET/CT can be useful for delimiting the hypoxic areas, due to glucose consumption enhancement by Pasteur effect in hypoxic cells. Although most participating patients complain of lost time, all of them will participate again. Supported by ISCIII Grant PI11/02035.
Medical Physics, 2009
Purpose: Modern radiotherapy uses complex treatments that necessitate more complex quality assura... more Purpose: Modern radiotherapy uses complex treatments that necessitate more complex quality assurance procedures. As a continuous medium, GafChromic EBT films offer suitable features for such verification. However, its sensitometric curve is not fully understood in terms of classical theoretical models. In fact, measured optical densities and those predicted by the classical models differ significantly. This difference increases systematically with wider dose ranges. Thus, achieving the accuracy required for intensity-modulated radiotherapy ͑IMRT͒ by classical methods is not possible, plecluding their use. As a result, experimental parametrizations, such as polynomial fits, are replacing phenomenological expressions in modern investigations. This article focuses on identifying new theoretical ways to describe sensitometric curves and on evaluating the quality of fit for experimental data based on four proposed models. Methods: A whole mathematical formalism starting with a geometrical version of the classical theory is used to develop new expressions for the sensitometric curves. General results from the percolation theory are also used. A flat-bed-scanner-based method was chosen for the film analysis. Different tests were performed, such as consistency of the numeric results for the proposed model and double examination using data from independent researchers. Results: Results show that the percolation-theory-based model provides the best theoretical explanation for the sensitometric behavior of GafChromic films. The different sizes of active centers or monomer crystals of the film are the basis of this model, allowing acquisition of information about the internal structure of the films. Values for the mean size of the active centers were obtained in accordance with technical specifications. In this model, the dynamics of the interaction between the active centers of GafChromic film and radiation is also characterized by means of its interaction cross-section value. Conclusions: The percolation model fulfills the accuracy requirements for quality-control procedures when large ranges of doses are used and offers a physical explanation for the film response.
Medical Physics, 2012
Currently, quality control (QC) for each IMRT treatment is performed by dose distribution measure... more Currently, quality control (QC) for each IMRT treatment is performed by dose distribution measurements. These techniques are very time-consuming and require long accelerator downtime. QC could be only based in verification of monitor units and dose distributions, if precise control of MLC is carried out. In such a manner, the e-IMRT platform (http://eimrt.cesga.es/) is a remote distributed computing tool, which allows comparison between the dose distributions calculated by a TPS and those calculated by Monte Carlo (MC). Previously, our linear accelerator (Oncor Impression, Siemens) was commissioned. For this purpose, comparison of experimental and MC simulated data was carried out. Several IMRT treatments plans were calculated in superposition algorithm (TPS Xio®CMS 4.60.00) and used as input data for the e-IMRT platform. These treatment plans were previously verified employing a 2D array MapCheckTM, Sun Nuclear. The gamma index (3%, 3mm) was used for validating results. The platform displays calculated doses using MC, also gamma map (in the CT images, not only statistical data) and histogram shown in Figures 1a), b) and d). The gamma map illustrates the differences between the input and calculated doses. According to the legend in Figure 1 d), these differences correspond to less than 1%. Results show good agreement between the doses calculated by TPS and those computed by e-IMRT platform. If a rigorous quality control is established for MLC and optimisation criteria (number of gantry angles, minimum segment size, levels of intensity for fluency map) are used. Then, QC for IMRT standard treatment plans would be only based on the verification of monitor units and dose distributions using e-IMRT II.This work has been funded by the Xunta de Galicia, Project R&D Grant 09SIN007CT. We would like to thank Centro de SupercomputaciÃ3 n de Galicia for the computational resources and support.