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Papers by marta casati

Journal of Applied Clinical Medical Physics

Purpose: Patient-specific quality assurance (QA) is very important in radiotherapy, especially fo... more Purpose: Patient-specific quality assurance (QA) is very important in radiotherapy, especially for patients with highly conformed treatment plans like VMAT plans. Traditional QA protocols for these plans are time-consuming reducing considerably the time available for patient treatments. In this work, a new MC-based secondary dose check software (SciMoCa) is evaluated and benchmarked against well-established TPS (Monaco and Pinnacle 3) by means of treatment plans and dose measurements. Methods: Fifty VMAT plans have been computed using same calculation parameters with SciMoCa and the two primary TPSs. Plans were validated with measurements performed with a 3D diode detector (ArcCHECK) by translating patient plans to phantom geometry. Calculation accuracy was assessed by measuring point dose differences and gamma passing rates (GPR) from a 3D gamma analysis with 3%-2 mm criteria. Comparison between SciMoCa and primary TPS calculations was made using the same estimators and using both patient and phantom geometry plans. Results: TPS and SciMoCa calculations were found to be in very good agreement with validation measurements with average point dose differences of 0.7 AE 1.7% and −0.2 AE 1.6% for SciMoCa and two TPSs, respectively. Comparison between SciMoCa calculations and the two primary TPS plans did not show any statistically significant difference with average point dose differences compatible with zero within error for both patient and phantom geometry plans and GPR (98.0 AE 3.0% and 99.0 AE 3.0% respectively) well in excess of the typical 95%clinical tolerance threshold. Conclusion: This work presents results obtained with a significantly larger sample than other similar analyses and, to the authors' knowledge, compares SciMoCa with a MC-based TPS for the first time. Results show that a MC-based secondary patient-specific QA is a clinically viable, reliable, and promising technique, that potentially allows significant time saving that can be used for patient treatment and a per-plan basis QA that effectively complements traditional commissioning and calibration protocols.

Radiotherapy and Oncology, 2021

Radiotherapy and Oncology, 2021

Physica Medica, 2021

PURPOSE The influence of basic plan parameters such as slice thickness, grid resolution, algorith... more PURPOSE The influence of basic plan parameters such as slice thickness, grid resolution, algorithm type and field size on calculated small field output factors (OFs) was evaluated in a multicentric study. METHODS AND MATERIALS Three computational homogeneous water phantoms with slice thicknesses (ST) 1, 2 and 3 mm were shared among twenty-one centers to calculate OFs for 1x1, 2x2 and 3x3 cm2 field sizes (FSs) (normalized to 10x10 cm2 FS), with their own treatment planning system (TPS) and the energy clinically used for stereotactic body radiation therapy delivery. OFs were calculated for each combination of grid resolution (GR) (1, 2 and 3 mm) and ST and finally compared with the OFs measured for the TPS commissioning. A multivariate analysis was performed to test the effect of basic plan parameters on calculated OFs. RESULTS A total of 509 data points were collected. Calculated OFs are slightly higher than measured ones. The multivariate analysis showed that Center, GR, algorithm type, and FS are predictive variables of the difference between calculated and measured OFs (p < 0.001). As FS decreases, the spread in the difference between calculated and measured OFs became larger when increasing the GR. Monte Carlo and Analytical Anisotropic Algorithms, presented a dependence on GR (p < 0.01), while Collapsed Cone Convolution and Acuros did not. The effect of the ST was found to be negligible. CONCLUSIONS Modern TPSs slightly overestimate the calculated small field OFs compared with measured ones. Grid resolution, algorithm, center number and field size influence the calculation of small field OFs.

Radiotherapy and Oncology, 2019

Radiotherapy and Oncology, 2019

Physica Medica, 2018

sion/shape/shrinkage. Only 3 patients experienced >1 cc change of SL95%-105% during treatment (ma... more sion/shape/shrinkage. Only 3 patients experienced >1 cc change of SL95%-105% during treatment (maximum variation: 6 cc) while negative DSL95%-105% > 1 cc, up to 17 cc, were seen in 15/33 patients. A negative change was correlated with the presence of some overlap between PTV and SL at planning (p = 0.03). DSL 95% are shown for all patients in Fig. 1. Conclusions. Most patients treated with a SIB approach with Tomotherapy for HN cancer showed negative or irrelevant changes to the dose delivered to the skin. Less than 10% of patients seem to be candidate to ART to counteract any significant skin dose increase during therapy.

Physica Medica, 2016

Os autores agradecem à equipe do Núcleo de Pesquisas Proluta/UFG, em especial a Lira Furtado More... more Os autores agradecem à equipe do Núcleo de Pesquisas Proluta/UFG, em especial a Lira Furtado Moreno, pelas contribuições aos estudos que fundamentam este artigo.

Radiotherapy and Oncology, 2016

ESTRO 35 2016 S215 ______________________________________________________________________________... more ESTRO 35 2016 S215 ______________________________________________________________________________________________________ technology. Imaging using MRI shows advantages compared to CT or CBCT offering superior soft tissue contrast without additional dose. Also in particle beam therapy integrated MR guided treatment units have great potential. A complete understanding of the particle beam characteristics in the presence of magnetic fields is required. So far, studies in this area are limited. Material and Methods: Protons (60-250MeV) and carbon ions (120-400MeV/u) in the clinically required energy range impinging on a phantom of 35x35x50cm³ size were simulated using the MC framework GATE 7. Homogeneous magnetic fields of 0.35T, 1T and 3T perpendicular to the initial beam axis were applied. The beam deflection, shape, and the energy spectrum at the Bragg peak area was analyzed. A numerical algorithm was developed for deflection curve generation solving the relativistic equations of motion taking into account the Lorentz force and particle energy loss. Additionally, dose variations on material boundaries induced by magnetic fields were investigated for 250MeV protons. Results: Transverse deflections up to 99mm were observed for 250MeV protons at 3T. Deflections for lower field strengths (e.g. future hybrid open-MRI proton delivery systems) yielded 12mm for 0.35T and 34mm for 1T. A change in the dose distribution at the Bragg-peak region was observed for protons. Energy spectrum analysis showed an asymmetric lateral energy distribution. The different particle ranges resulted in a tilted dose distribution, see Fig.1.The numerical algorithm successfully modeled the deflection curve, with a maximum deviation of 1.8% and calculation times of less than 5ms. For a 250MeV proton beam passing in a 3T field through multiple slabs (water-air-water), only a 4% local dose increase at the first boundary was observed in single voxels due to the electron return effect.

Radiotherapy and Oncology, 2015

Journal of Applied Clinical Medical Physics

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, Jan 30, 2018

Reported plan quality improvements with autoplanning of radiotherapy of the prostate and seminal ... more Reported plan quality improvements with autoplanning of radiotherapy of the prostate and seminal vesicles are poor. A system for automated multi-criterial planning has been validated for this treatment in a large international multi-center study. The system is configured with training plans using a mechanism that strives for quality improvements relative to those plans. Each of the four participating centers included thirty manually generated clinical Volumetric Modulated Arc Therapy prostate plans (manVMAT). Ten plans were used for autoplanning training. The other twenty were compared with an automatically generated plan (autoVMAT). Plan evaluations considered dosimetric plan parameters and blinded side-by-side plan comparisons by clinicians. With equivalent Planning Target Volume (PTV) V, D, D, and dose homogeneity autoVMAT was overall superior for rectum with median differences of 3.4 Gy (p < 0.001) in D, 4.0% (p < 0.001) in V, and 1.5% (p = 0.001) in V, and for bladder D (...

Radiotherapy and Oncology, 2020

Critical Reviews in Oncology/Hematology

Journal of Applied Clinical Medical Physics

Purpose: Patient-specific quality assurance (QA) is very important in radiotherapy, especially fo... more Purpose: Patient-specific quality assurance (QA) is very important in radiotherapy, especially for patients with highly conformed treatment plans like VMAT plans. Traditional QA protocols for these plans are time-consuming reducing considerably the time available for patient treatments. In this work, a new MC-based secondary dose check software (SciMoCa) is evaluated and benchmarked against well-established TPS (Monaco and Pinnacle 3) by means of treatment plans and dose measurements. Methods: Fifty VMAT plans have been computed using same calculation parameters with SciMoCa and the two primary TPSs. Plans were validated with measurements performed with a 3D diode detector (ArcCHECK) by translating patient plans to phantom geometry. Calculation accuracy was assessed by measuring point dose differences and gamma passing rates (GPR) from a 3D gamma analysis with 3%-2 mm criteria. Comparison between SciMoCa and primary TPS calculations was made using the same estimators and using both patient and phantom geometry plans. Results: TPS and SciMoCa calculations were found to be in very good agreement with validation measurements with average point dose differences of 0.7 AE 1.7% and −0.2 AE 1.6% for SciMoCa and two TPSs, respectively. Comparison between SciMoCa calculations and the two primary TPS plans did not show any statistically significant difference with average point dose differences compatible with zero within error for both patient and phantom geometry plans and GPR (98.0 AE 3.0% and 99.0 AE 3.0% respectively) well in excess of the typical 95%clinical tolerance threshold. Conclusion: This work presents results obtained with a significantly larger sample than other similar analyses and, to the authors' knowledge, compares SciMoCa with a MC-based TPS for the first time. Results show that a MC-based secondary patient-specific QA is a clinically viable, reliable, and promising technique, that potentially allows significant time saving that can be used for patient treatment and a per-plan basis QA that effectively complements traditional commissioning and calibration protocols.

Radiotherapy and Oncology, 2021

Radiotherapy and Oncology, 2021

Physica Medica, 2021

PURPOSE The influence of basic plan parameters such as slice thickness, grid resolution, algorith... more PURPOSE The influence of basic plan parameters such as slice thickness, grid resolution, algorithm type and field size on calculated small field output factors (OFs) was evaluated in a multicentric study. METHODS AND MATERIALS Three computational homogeneous water phantoms with slice thicknesses (ST) 1, 2 and 3 mm were shared among twenty-one centers to calculate OFs for 1x1, 2x2 and 3x3 cm2 field sizes (FSs) (normalized to 10x10 cm2 FS), with their own treatment planning system (TPS) and the energy clinically used for stereotactic body radiation therapy delivery. OFs were calculated for each combination of grid resolution (GR) (1, 2 and 3 mm) and ST and finally compared with the OFs measured for the TPS commissioning. A multivariate analysis was performed to test the effect of basic plan parameters on calculated OFs. RESULTS A total of 509 data points were collected. Calculated OFs are slightly higher than measured ones. The multivariate analysis showed that Center, GR, algorithm type, and FS are predictive variables of the difference between calculated and measured OFs (p < 0.001). As FS decreases, the spread in the difference between calculated and measured OFs became larger when increasing the GR. Monte Carlo and Analytical Anisotropic Algorithms, presented a dependence on GR (p < 0.01), while Collapsed Cone Convolution and Acuros did not. The effect of the ST was found to be negligible. CONCLUSIONS Modern TPSs slightly overestimate the calculated small field OFs compared with measured ones. Grid resolution, algorithm, center number and field size influence the calculation of small field OFs.

Radiotherapy and Oncology, 2019

Radiotherapy and Oncology, 2019

Physica Medica, 2018

sion/shape/shrinkage. Only 3 patients experienced >1 cc change of SL95%-105% during treatment (ma... more sion/shape/shrinkage. Only 3 patients experienced >1 cc change of SL95%-105% during treatment (maximum variation: 6 cc) while negative DSL95%-105% > 1 cc, up to 17 cc, were seen in 15/33 patients. A negative change was correlated with the presence of some overlap between PTV and SL at planning (p = 0.03). DSL 95% are shown for all patients in Fig. 1. Conclusions. Most patients treated with a SIB approach with Tomotherapy for HN cancer showed negative or irrelevant changes to the dose delivered to the skin. Less than 10% of patients seem to be candidate to ART to counteract any significant skin dose increase during therapy.

Physica Medica, 2016

Os autores agradecem à equipe do Núcleo de Pesquisas Proluta/UFG, em especial a Lira Furtado More... more Os autores agradecem à equipe do Núcleo de Pesquisas Proluta/UFG, em especial a Lira Furtado Moreno, pelas contribuições aos estudos que fundamentam este artigo.

Radiotherapy and Oncology, 2016

ESTRO 35 2016 S215 ______________________________________________________________________________... more ESTRO 35 2016 S215 ______________________________________________________________________________________________________ technology. Imaging using MRI shows advantages compared to CT or CBCT offering superior soft tissue contrast without additional dose. Also in particle beam therapy integrated MR guided treatment units have great potential. A complete understanding of the particle beam characteristics in the presence of magnetic fields is required. So far, studies in this area are limited. Material and Methods: Protons (60-250MeV) and carbon ions (120-400MeV/u) in the clinically required energy range impinging on a phantom of 35x35x50cm³ size were simulated using the MC framework GATE 7. Homogeneous magnetic fields of 0.35T, 1T and 3T perpendicular to the initial beam axis were applied. The beam deflection, shape, and the energy spectrum at the Bragg peak area was analyzed. A numerical algorithm was developed for deflection curve generation solving the relativistic equations of motion taking into account the Lorentz force and particle energy loss. Additionally, dose variations on material boundaries induced by magnetic fields were investigated for 250MeV protons. Results: Transverse deflections up to 99mm were observed for 250MeV protons at 3T. Deflections for lower field strengths (e.g. future hybrid open-MRI proton delivery systems) yielded 12mm for 0.35T and 34mm for 1T. A change in the dose distribution at the Bragg-peak region was observed for protons. Energy spectrum analysis showed an asymmetric lateral energy distribution. The different particle ranges resulted in a tilted dose distribution, see Fig.1.The numerical algorithm successfully modeled the deflection curve, with a maximum deviation of 1.8% and calculation times of less than 5ms. For a 250MeV proton beam passing in a 3T field through multiple slabs (water-air-water), only a 4% local dose increase at the first boundary was observed in single voxels due to the electron return effect.

Radiotherapy and Oncology, 2015

Journal of Applied Clinical Medical Physics

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, Jan 30, 2018

Reported plan quality improvements with autoplanning of radiotherapy of the prostate and seminal ... more Reported plan quality improvements with autoplanning of radiotherapy of the prostate and seminal vesicles are poor. A system for automated multi-criterial planning has been validated for this treatment in a large international multi-center study. The system is configured with training plans using a mechanism that strives for quality improvements relative to those plans. Each of the four participating centers included thirty manually generated clinical Volumetric Modulated Arc Therapy prostate plans (manVMAT). Ten plans were used for autoplanning training. The other twenty were compared with an automatically generated plan (autoVMAT). Plan evaluations considered dosimetric plan parameters and blinded side-by-side plan comparisons by clinicians. With equivalent Planning Target Volume (PTV) V, D, D, and dose homogeneity autoVMAT was overall superior for rectum with median differences of 3.4 Gy (p < 0.001) in D, 4.0% (p < 0.001) in V, and 1.5% (p = 0.001) in V, and for bladder D (...

Radiotherapy and Oncology, 2020

Critical Reviews in Oncology/Hematology