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6 pages, 191 KiB

Open AccessEditorial

Applications of Medical Physics

by Salvatore Gallo and Ivan Veronese

Appl. Sci. 2022, 12(4), 1852; https://doi.org/10.3390/app12041852 - 11 Feb 2022

Cited by 1 | Viewed by 4342

Abstract

Since the discovery of X-rays, the use of the principles and methods of physics in medicine has contributed to the improvement of human health [...] Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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14 pages, 1207 KiB

Open AccessFeature PaperArticle

Radiobiological Outcomes, Microdosimetric Evaluations and Monte Carlo Predictions in Eye Proton Therapy

by Giada Petringa, Marco Calvaruso, Valeria Conte, Pavel Bláha, Valentina Bravatà, Francesco Paolo Cammarata, Giacomo Cuttone, Giusi Irma Forte, Otilija Keta, Lorenzo Manti, Luigi Minafra, Vladana Petković, Ivan Petrović, Selene Richiusa, Aleksandra Ristić Fira, Giorgio Russo and Giuseppe Antonio Pablo Cirrone

Appl. Sci. 2021, 11(19), 8822; https://doi.org/10.3390/app11198822 - 23 Sep 2021

Cited by 3 | Viewed by 2589

Abstract

CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) was the first Italian protontherapy facility dedicated to the treatment of ocular neoplastic pathologies. It is in operation at the LNS Laboratories of the Italian Institute for Nuclear Physics (INFN-LNS) and to date, 500 patients [...] Read more.

CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) was the first Italian protontherapy facility dedicated to the treatment of ocular neoplastic pathologies. It is in operation at the LNS Laboratories of the Italian Institute for Nuclear Physics (INFN-LNS) and to date, 500 patients have been successfully treated. Even though proton therapy has demonstrated success in clinical settings, there is still a need for more accurate models because they are crucial for the estimation of clinically relevant RBE values. Since RBE can vary depending on several physical and biological parameters, there is a clear need for more experimental data to generate predictions. Establishing a database of cell survival experiments is therefore useful to accurately predict the effects of irradiations on both cancerous and normal tissue. The main aim of this work was to compare RBE values obtained from in-vitro experimental data with predictions made by the LEM II (Local Effect Model), Monte Carlo approaches, and semi-empirical models based on LET experimental measurements. For this purpose, the 92.1 uveal melanoma and ARPE-19 cells derived from normal retinal pigmented epithelium were selected and irradiated in the middle of clinical SOBP of the CATANA proton therapy facility. The remarkable results show the potentiality of using microdosimetric spectrum, Monte Carlo simulations and LEM model to predict not only the RBE but also the survival curves. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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11 pages, 11180 KiB

Open AccessArticle

On the Possibility to Use the Charge Imbalance in Patients Undergoing Radiotherapy: A New Online, In Vivo, Noninvasive Dose Monitoring System

by G A Pablo Cirrone, Nino Amato, Roberto Catalano, Alessandro Di Domenico, Giacomo Cuttone, Pietro Lojacono, Alfio Mazzaglia, Fabrizio Pace, Giuseppe Pittà, Luigi Raffaele, Vincenzo Salamone, Corrado Spatola and Giada Petringa

Appl. Sci. 2021, 11(15), 7005; https://doi.org/10.3390/app11157005 - 29 Jul 2021

Cited by 3 | Viewed by 1884

Abstract

This paper describes a new real-time, in vivo, noninvasive, biasless detector system acting as a beam monitoring and relative dose measurement system. The detector is based on the idea that when a beam current is injected into the body of a patient undergoing [...] Read more.

This paper describes a new real-time, in vivo, noninvasive, biasless detector system acting as a beam monitoring and relative dose measurement system. The detector is based on the idea that when a beam current is injected into the body of a patient undergoing a charged particle therapy, the current itself can be collected using a conductive electrode in contact with the patient’s skin. This new approach was studied in vitro using an electrically isolated water tank irradiated with monoenergetic proton beams. The conductive electrode was immersed in water and positioned outside the irradiation field. The detection system performance was evaluated by comparing its response against a SEM (Secondary Emission Monitor) detector, used as a reference beam current monitor, and an Advanced Markus ionization chamber. Short-, mid- and long-term reproducibility, current monitoring capability, field size dependence, electrode position and environment temperature dependence, linearity with dose, and dose rate dependence were investigated. Few preliminary in vivo tests were also performed that demonstrated the possibility to apply the system in clinical practice. The potential of the proposed method is considerable, representing a simple and economical system for online, in vivo, and noninvasive monitoring of the beam current and relative released dose into the patient during treatment, without perturbing the irradiation field. The system presented in this work is protected with both a National Italian (N. 102017000087851) and an International N. WO 2019/025933 patent. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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14 pages, 13671 KiB

Open AccessFeature PaperArticle

A Voxel-Based Assessment of Noise Properties in Computed Tomography Imaging with the ASiR-V and ASiR Iterative Reconstruction Algorithms

by Patrizio Barca, Daniela Marfisi, Chiara Marzi, Sabino Cozza, Stefano Diciotti, Antonio Claudio Traino and Marco Giannelli

Appl. Sci. 2021, 11(14), 6561; https://doi.org/10.3390/app11146561 - 16 Jul 2021

Cited by 4 | Viewed by 2956

Abstract

Given the inherent characteristics of nonlinearity and nonstationarity of iterative reconstruction algorithms in computed tomography (CT) imaging, this study aimed to perform, for the first time, a voxel-based characterization of noise properties in CT imaging with the ASiR-V and ASiR algorithms as compared [...] Read more.

Given the inherent characteristics of nonlinearity and nonstationarity of iterative reconstruction algorithms in computed tomography (CT) imaging, this study aimed to perform, for the first time, a voxel-based characterization of noise properties in CT imaging with the ASiR-V and ASiR algorithms as compared with conventional filtered back projection (FBP). Multiple repeated scans of the Catphan-504 phantom were carried out. CT images were reconstructed using FBP and ASiR/ASiR-V with different blending levels of reconstruction (20%, 40%, 60%, 80%, 100%). Noise maps and their nonuniformity index (NUI) were obtained according to the approach proposed by the report of AAPM TG-233. For the homogeneous CTP486 module, ASiR-V/ASiR allowed a noise reduction of up to 63.7%/52.9% relative to FBP. While the noise reduction values of ASiR-V-/ASiR-reconstructed images ranged up to 33.8%/39.9% and 31.2%/35.5% for air and Teflon contrast objects, respectively, these values were approximately 60%/50% for other contrast objects (PMP, LDPE, polystyrene, acrylic, Delrin). Moreover, for all contrast objects but air and Teflon, ASiR-V showed a greater noise reduction potential than ASiR when the blending level was ≥40%. While noise maps of the homogenous CTP486 module showed only a slight spatial variation of noise (NUI < 5.2%) for all reconstruction algorithms, the NUI values of iterative-reconstructed images of the nonhomogeneous CTP404 module increased nonlinearly with blending level and were 19%/15% and 6.7% for pure ASiR-V/ASiR and FBP, respectively. Overall, these results confirm the potential of ASiR-V and ASiR in reducing noise as compared with conventional FBP, suggesting, however, that the use of pure ASiR-V or ASiR might be suboptimal for specific clinical applications. Full article

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14 pages, 1749 KiB

Open AccessArticle

Correction for the Partial Volume Effects (PVE) in Nuclear Medicine Imaging: A Post-Reconstruction Analytic Method

by Fabio Di Martino, Patrizio Barca, Eleonora Bortoli, Alessia Giuliano and Duccio Volterrani

Appl. Sci. 2021, 11(14), 6460; https://doi.org/10.3390/app11146460 - 13 Jul 2021

Cited by 3 | Viewed by 2460

Abstract

Quantitative analyses in nuclear medicine are increasingly used, both for diagnostic and therapeutic purposes. The Partial Volume Effect (PVE) is the most important factor of loss of quantification in Nuclear Medicine, especially for evaluation in Region of Interest (ROI) smaller than the Full [...] Read more.

Quantitative analyses in nuclear medicine are increasingly used, both for diagnostic and therapeutic purposes. The Partial Volume Effect (PVE) is the most important factor of loss of quantification in Nuclear Medicine, especially for evaluation in Region of Interest (ROI) smaller than the Full Width at Half Maximum (FWHM) of the PSF. The aim of this work is to present a new approach for the correction of PVE, using a post-reconstruction process starting from a mathematical expression, which only requires the knowledge of the FWHM of the final PSF of the imaging system used. After the presentation of the theoretical derivation, the experimental evaluation of this method is performed using a PET/CT hybrid system and acquiring the IEC NEMA phantom with six spherical “hot” ROIs (with diameters of 10, 13, 17, 22, 28, and 37 mm) and a homogeneous “colder” background. In order to evaluate the recovery of quantitative data, the effect of statistical noise (different acquisition times), tomographic reconstruction algorithm with and without time-of-flight (TOF) and different signal-to-background activity concentration ratio (3:1 and 10:1) was studied. The application of the corrective method allows recovering the loss of quantification due to PVE for all sizes of spheres acquired, with a final accuracy less than 17%, for lesion dimensions larger than two FWHM and for acquisition times equal to or greater than two minutes. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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24 pages, 4118 KiB

Open AccessArticle

Classification Performance for COVID Patient Prognosis from Automatic AI Segmentation—A Single-Center Study

by Riccardo Biondi, Nico Curti, Francesca Coppola, Enrico Giampieri, Giulio Vara, Michele Bartoletti, Arrigo Cattabriga, Maria Adriana Cocozza, Federica Ciccarese, Caterina De Benedittis, Laura Cercenelli, Barbara Bortolani, Emanuela Marcelli, Luisa Pierotti, Lidia Strigari, Pierluigi Viale, Rita Golfieri and Gastone Castellani

Appl. Sci. 2021, 11(12), 5438; https://doi.org/10.3390/app11125438 - 11 Jun 2021

Cited by 7 | Viewed by 3388

Abstract

Background: COVID assessment can be performed using the recently developed individual risk score (prediction of severe respiratory failure in hospitalized patients with SARS-COV2 infection, PREDI-CO score) based on High Resolution Computed Tomography. In this study, we evaluated the possibility of automatizing this estimation [...] Read more.

Background: COVID assessment can be performed using the recently developed individual risk score (prediction of severe respiratory failure in hospitalized patients with SARS-COV2 infection, PREDI-CO score) based on High Resolution Computed Tomography. In this study, we evaluated the possibility of automatizing this estimation using semi-supervised AI-based Radiomics, leveraging the possibility of performing non-supervised segmentation of ground-glass areas. Methods: We collected 92 from patients treated in the IRCCS Sant’Orsola-Malpighi Policlinic and public databases; each lung was segmented using a pre-trained AI method; ground-glass opacity was identified using a novel, non-supervised approach; radiomic measurements were collected and used to predict clinically relevant scores, with particular focus on mortality and the PREDI-CO score. We compared the prediction obtained through different machine learning approaches. Results: All the methods obtained a well-balanced accuracy (70%) on the PREDI-CO score but did not obtain satisfying results on other clinical characteristics due to unbalance between the classes. Conclusions: Semi-supervised segmentation, implemented using a combination of non-supervised segmentation and feature extraction, seems to be a viable approach for patient stratification and could be leveraged to train more complex models. This would be useful in a high-demand situation similar to the current pandemic to support gold-standard segmentation for AI training. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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12 pages, 8299 KiB

Open AccessArticle

The Impact of Radiation to Epicardial Adipose Tissue on Prognosis of Esophageal Squamous Cell Carcinoma Receiving Neoadjuvant Chemoradiotherapy and Esophagectomy

by Hung-Chi Tai, Jie Lee, Wen-Chien Huang, Hung-Chang Liu, Chao-Hung Chen, Yu-Chuen Huang, Chi-Jung Lee, Chun-Ho Yun, Shih-Ming Hsu and Yu-Jen Chen

Appl. Sci. 2021, 11(9), 4023; https://doi.org/10.3390/app11094023 - 28 Apr 2021

Cited by 2 | Viewed by 1858

Abstract

The epicardial adipose tissue (EAT), mainly composed of brown adipose tissue, is a metabolically active tissue releasing various bioactive factors with a critical role in metabolic diseases. The EAT is often irradiated during radiotherapy in patients with esophageal cancer due to its proximity [...] Read more.

The epicardial adipose tissue (EAT), mainly composed of brown adipose tissue, is a metabolically active tissue releasing various bioactive factors with a critical role in metabolic diseases. The EAT is often irradiated during radiotherapy in patients with esophageal cancer due to its proximity to the target region. We aimed to evaluate the effect of radiation to the EAT on survival outcomes in patients with esophageal cancer receiving neoadjuvant chemoradiotherapy followed by esophagectomy. We analyzed data on 36 patients with esophageal cancer treated with trimodal therapy between 2012 and 2017. The median follow-up period was 22.0 months. The 3-year overall survival and progression-free survival rates were 39.7% and 32.5%, respectively. Multivariate analysis revealed that higher EAT-REI was independently associated with worse overall survival (hazard ratio: 1.002, p = 0.028) and progression-free survival (hazard ratio: 1.002, p = 0.03). The cutoff value with the highest accuracy for avoiding mortality was EAT-REI = 68.8 cGy/mL (area under the curve, 0.78, p = 0.006). The 3-year overall survival rate in patients with EAT-REI ≥68.8 and <68.8 was 21.7% and 71.9%, respectively (p = 0.003). The EAT should be considered an organ at risk during radiotherapy in patients with esophageal cancer. EAT-REI might serve as a biomarker of survival outcomes in these patients. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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10 pages, 2034 KiB

Open AccessArticle

[99mTc]Tc-Sestamibi Bioaccumulation Can Induce Apoptosis in Breast Cancer Cells: Molecular and Clinical Perspectives

by Nicoletta Urbano, Manuel Scimeca, Rita Bonfiglio, Alessandro Mauriello, Elena Bonanno and Orazio Schillaci

Appl. Sci. 2021, 11(6), 2733; https://doi.org/10.3390/app11062733 - 18 Mar 2021

Cited by 3 | Viewed by 2433

Abstract

The aim of this study was to investigate the possible role of [99mTc]Tc-Sestamibi in the regulation of cancer cell proliferation and apoptosis. To this end, the in vivo values of [99mTc]Tc-Sestamibi uptake have been associated with the in-situ expression of both Ki67 and [...] Read more.

The aim of this study was to investigate the possible role of [99mTc]Tc-Sestamibi in the regulation of cancer cell proliferation and apoptosis. To this end, the in vivo values of [99mTc]Tc-Sestamibi uptake have been associated with the in-situ expression of both Ki67 and caspase-3. For in vitro investigations, BT-474 cells were incubated with three different concentrations of [99mTc]Tc-Sestamibi: 10 µg/mL, 1 µg/mL, and 0.1 µg/mL. Expression of caspase-3 and Ki67, as well as the ultrastructure of cancer cells, was evaluated at T0 and after 24, 48, 72, and 120 h after [99mTc]Tc-Sestamibi incubation. Ex vivo data strengthened the known association between sestamibi uptake and Ki67 expression. Linear regression analysis showed a significant association between sestamibi uptake and the number of apoptotic cells evaluated as caspase-3-positive breast cancer cells. As concerning the in vitro data, a significant decrease of the proliferation index was observed in breast cancer cells incubated with a high concentration of [99mTc]Tc-Sestamibi (10 µg/mL). Amazingly, a significant increase in caspase-3-positive cells in cultures incubated with 10 µg/mL [99mTc]Tc-Sestamibi was observed. This study suggested the possible role of sestamibi in the regulation of pathophysiological processes involved in breast cancer. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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16 pages, 4365 KiB

Open AccessArticle

Feasibility Study of Robust Optimization to Reduce Dose Delivery Uncertainty by Potential Applicator Displacements for a Cervix Brachytherapy

by Byungdu Jo, Kyeongyun Park, Dongho Shin, Young Kyung Lim, Jong Hwi Jeong, Se Byeong Lee, Hee-Joung Kim and Haksoo Kim

Appl. Sci. 2021, 11(6), 2592; https://doi.org/10.3390/app11062592 - 14 Mar 2021

Cited by 5 | Viewed by 2905

Abstract

Brachytherapy is an important technique to increase the overall survival of cervical cancer patients. However, a possible shift of the applicators in relation to the target and organs at risk may occur between imaging and treatment. Without daily adaptive brachytherapy planning, these applicator [...] Read more.

Brachytherapy is an important technique to increase the overall survival of cervical cancer patients. However, a possible shift of the applicators in relation to the target and organs at risk may occur between imaging and treatment. Without daily adaptive brachytherapy planning, these applicator displacements can lead to a significant change in dose distribution. In order to resolve it, a robust optimization method had been developed using a genetic algorithm combined with a median absolute deviation as a robustness evaluation function. The resulting robustness plans from our strategy might be worth considering according to the GEC-ESTRO guidelines. From the point of view of dose delivery uncertainty from applicator displacement, the robust optimization may be considered with caution in a single-plan approach for High Dose Rate brachytherapy treatment planning and should be confirmed by a more thorough investigation. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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13 pages, 1751 KiB

Open AccessArticle

Evaluation of Organ Dose and Image Quality Metrics of Pediatric CT Chest-Abdomen-Pelvis (CAP) Examination: An Anthropomorphic Phantom Study

by Nor Azura Muhammad, Zunaide Kayun, Hasyma Abu Hassan, Jeannie Hsiu Ding Wong, Kwan Hoong Ng and Muhammad Khalis Abdul Karim

Appl. Sci. 2021, 11(5), 2047; https://doi.org/10.3390/app11052047 - 25 Feb 2021

Cited by 9 | Viewed by 3372

Abstract

The aim of this study is to investigate the impact of CT acquisition parameter setting on organ dose and its influence on image quality metrics in pediatric phantom during CT examination. The study was performed on 64-slice multidetector CT scanner (MDCT) Siemens Definition [...] Read more.

The aim of this study is to investigate the impact of CT acquisition parameter setting on organ dose and its influence on image quality metrics in pediatric phantom during CT examination. The study was performed on 64-slice multidetector CT scanner (MDCT) Siemens Definition AS (Siemens Sector Healthcare, Forchheim, Germany) using various CT CAP protocols (P1–P9). Tube potential for P1, P2, and P3 protocols were fixed at 100 kVp while P4, P5, and P6 were fixed at 80 kVp with used of various reference noise values. P7, P8, and P9 were the modification of P1 with changes on slice collimation, pitch factor, and tube current modulation (TCM), respectively. TLD-100 chips were inserted into the phantom slab number 7, 9, 10, 12, 13, and 14 to represent thyroid, lung, liver, stomach, gonads, and skin, respectively. The image quality metrics, signal to noise ratio (SNR) and contrast to noise ratio (CNR) values were obtained from the CT console. As a result, this study indicates a potential reduction in the absorbed dose up to 20% to 50% along with reducing tube voltage, tube current, and increasing the slice collimation. There is no significant difference (p > 0.05) observed between the protocols and image metrics. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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16 pages, 17713 KiB

Open AccessArticle

In Silico Validation of MCID Platform for Monte Carlo-Based Voxel Dosimetry Applied to ⁹⁰Y-Radioembolization of Liver Malignancies

by Alessia Milano, Alex Vergara Gil, Enrico Fabrizi, Marta Cremonesi, Ivan Veronese, Salvatore Gallo, Nico Lanconelli, Riccardo Faccini and Massimiliano Pacilio

Appl. Sci. 2021, 11(4), 1939; https://doi.org/10.3390/app11041939 - 23 Feb 2021

Cited by 12 | Viewed by 2594

Abstract

The aim was the validation of a platform for internal dosimetry, named MCID, based on patient-specific images and direct Monte Carlo (MC) simulations, for radioembolization of liver tumors with ⁹⁰Y-labeled microspheres. CT of real patients were used to create voxelized phantoms with [...] Read more.

The aim was the validation of a platform for internal dosimetry, named MCID, based on patient-specific images and direct Monte Carlo (MC) simulations, for radioembolization of liver tumors with ⁹⁰Y-labeled microspheres. CT of real patients were used to create voxelized phantoms with different density and activity maps. SPECT acquisitions were simulated by the SIMIND MC code. Input macros for the GATE/Geant4 code were generated by MCID, loading coregistered morphological and functional images and performing image segmentation. The dosimetric results obtained from the direct MC simulations and from conventional MIRD approach at both organ and voxel level, in condition of homogeneous tissues, were compared, obtaining differences of about 0.3% and within 3%, respectively, whereas differences increased (up to 14%) introducing tissue heterogeneities in phantoms. Mean absorbed dose for spherical regions of different sizes (10 mm ≤ r ≤ 30 mm) from MC code and from OLINDA/EXM were also compared obtaining differences varying in the range 7–69%, which decreased to 2–9% after correcting for partial volume effects (PVEs) from imaging, confirming that differences were mostly due to PVEs, even though a still high difference for the smallest sphere suggested possible source description mismatching. This study validated the MCID platform, which allows the fast implementation of a patient-specific GATE simulation, avoiding complex and time-consuming manual coding. It also points out the relevance of personalized dosimetry, accounting for inhomogeneities, in order to avoid absorbed dose misestimations. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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15 pages, 3539 KiB

Open AccessArticle

An Automatic Approach for Individual HU-Based Characterization of Lungs in COVID-19 Patients

by Aldo Mazzilli, Claudio Fiorino, Alessandro Loria, Martina Mori, Pier Giorgio Esposito, Diego Palumbo, Francesco de Cobelli and Antonella del Vecchio

Appl. Sci. 2021, 11(3), 1238; https://doi.org/10.3390/app11031238 - 29 Jan 2021

Cited by 7 | Viewed by 2500

Abstract

The ongoing COVID-19 pandemic currently involves millions of people worldwide. Radiology plays an important role in the diagnosis and management of patients, and chest computed tomography (CT) is the most widely used imaging modality. An automatic method to characterize the lungs of COVID-19 [...] Read more.

The ongoing COVID-19 pandemic currently involves millions of people worldwide. Radiology plays an important role in the diagnosis and management of patients, and chest computed tomography (CT) is the most widely used imaging modality. An automatic method to characterize the lungs of COVID-19 patients based on individually optimized Hounsfield unit (HU) thresholds was developed and implemented. Lungs were considered as composed of three components—aerated, intermediate, and consolidated. Three methods based on analytic fit (Gaussian) and maximum gradient search (using polynomial and original data fits) were implemented. The methods were applied to a population of 166 patients scanned during the first wave of the pandemic. Preliminarily, the impact of the inter-scanner variability of the HU-density calibration curve was investigated. Results showed that inter-scanner variability was negligible. The median values of individual thresholds th1 (between aerated and intermediate components) were −768, −780, and −798 HU for the three methods, respectively. A significantly lower median value for th2 (between intermediate and consolidated components) was found for the maximum gradient on the data (−34 HU) compared to the other two methods (−114 and −87 HU). The maximum gradient on the data method was applied to quantify the three components in our population—the aerated, intermediate, and consolidation components showed median values of 793 ± 499 cc, 914 ± 291 cc, and 126 ± 111 cc, respectively, while the median value of the first peak was −853 ± 56 HU. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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12 pages, 1542 KiB

Open AccessArticle

An Attempt to Reduce the Background Free Radicals in Fingernails for Monitoring Accidental Hand Exposure of Medical Workers

by Chryzel Angelica B. Gonzales, Jolan E. Taño and Hiroshi Yasuda

Appl. Sci. 2020, 10(24), 8949; https://doi.org/10.3390/app10248949 - 15 Dec 2020

Cited by 7 | Viewed by 2061

Abstract

While it is recognized that some medical workers could receive significantly higher radiation doses to their hands than the routinely monitored personal doses, accurate retrospective dosimetry of their hand exposure is still challenging. To solve this issue, a combination of electron spin resonance [...] Read more.

While it is recognized that some medical workers could receive significantly higher radiation doses to their hands than the routinely monitored personal doses, accurate retrospective dosimetry of their hand exposure is still challenging. To solve this issue, a combination of electron spin resonance (ESR) measurement and fingernails is worth to be investigated. However, the application of fingernail ESR dosimetry requires establishing an effective protocol to eliminate the background signal (BKG) which changes due to mechanical stress and other unclear factors, so that the radiation doses would be precisely evaluated from the radiation-induced signals (RIS) only. Thus, the authors investigated possible applications of antioxidants to remove or reduce the BKG in fingernails. In the present study, the effectiveness of chemical treatment using the dithiothreitol (DTT) reducing reagent was examined in irradiated and unirradiated fingernails. Chemically and non-chemically treated fingernails were subsequently exposed to 20 Gy of ¹³⁷Cs γ-rays and the time changes of the BKG and RIS were confirmed in two different storage conditions: vacuum chamber and freezer. The results show that the non-chemically treated fingernails displayed significant intra-individual variations in the peak-to-peak intensities of both BKG and RIS. RIS from chemically and non-chemically treated samples showed correlations after freezer storage; signals were more stable than the samples stored in the vacuum chamber. Moreover, while the BKG of non-chemically treated samples demonstrated higher levels than those chemically treated, the intra-individual variations were further reduced by the DTT treatment. Our results imply that the use of an antioxidant for hand washing of medical workers prior to starting their work could be effective in reducing the pre-existing free radicals in their fingernails. This also suggests a practical application of hand exposure monitoring using fingernails as a part of radiological emergency preparedness in occupations where radiation or radionuclides are used. Research for finding safer and easier-to-handle antioxidants is to be focused on in future studies. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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8 pages, 1251 KiB

Open AccessFeature PaperArticle

Diagnostic Performance and Radiation Dose of the EOS System to Image Enchondromatosis: A Phantom Study

by Domenico Albano, Alessandro Loria, Cristiana Fanciullo, Alberto Bruno, Carmelo Messina, Antonella del Vecchio and Luca Maria Sconfienza

Appl. Sci. 2020, 10(24), 8941; https://doi.org/10.3390/app10248941 - 15 Dec 2020

Cited by 6 | Viewed by 2317

Abstract

Background: Radiation doses and capability of EOS, conventional radiography (CR), and computed tomography (CT) to detect and measure enchondromas in a dedicated five-year-old anthropomorphic phantom were compared. Methods: To simulate enchondromas, minced pieces of chicken bone and cartilage were packed in conventional kitchen [...] Read more.

Background: Radiation doses and capability of EOS, conventional radiography (CR), and computed tomography (CT) to detect and measure enchondromas in a dedicated five-year-old anthropomorphic phantom were compared. Methods: To simulate enchondromas, minced pieces of chicken bone and cartilage were packed in conventional kitchen plastic foil to create ovoidal/rounded masses and randomly hung on the phantom. The phantom was imaged five times with CR, CT, and EOS, each time changing the number and position of inserts. All images were reviewed by a senior radiologist and a radiology resident. Results: EOS and CR detected all inserts in 4/5 cases (80%), while in one case 1/17 inserts was not seen. Excellent agreement of EOS with CR (88% reproducibility; bias = 14 mm; repeatability coefficient (CoR) 2.9; 95% CI from −2.8 to 3.1 mm; p = 0.5) and CT (81% reproducibility; bias = 15 mm; CoR 5.2; 95% CI from −5.5 to 5.2 mm; p = 0.7) was found. EOS showed 71% interobserver reproducibility (CoR 7.2; bias = 0.6 mm; 95% CI from −6.6 to 7.8 mm; p = 0.25). The EOS-Fast radiation dose was also significantly lower than the median radiation dose of CR (644.7 (599.4–651.97) mGy•cm², p = 0.004). Conclusions: Low-dose EOS has the same capability as CR to detect and measure enchondroma-like inserts on a phantom and may be considered to monitor patients with multiple enchondromas. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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10 pages, 1422 KiB

Open AccessFeature PaperArticle

Evaluation of an Early Regression Index (ERI_TCP) as Predictor of Pathological Complete Response in Cervical Cancer: A Pilot-Study

by Davide Cusumano, Francesco Catucci, Angela Romano, Luca Boldrini, Antonio Piras, Sara Broggi, Claudio Votta, Lorenzo Placidi, Matteo Nardini, Giuditta Chiloiro, Alessia Nardangeli, Viola De Luca, Bruno Fionda, Maura Campitelli, Rosa Autorino, Maria Antonietta Gambacorta, Luca Indovina, Claudio Fiorino and Vincenzo Valentini

Appl. Sci. 2020, 10(22), 8001; https://doi.org/10.3390/app10228001 - 11 Nov 2020

Cited by 13 | Viewed by 3071

Abstract

Background: Recent studies have highlighted the potentialities of a radiobiological parameter, the early regression index (ERI_TCP), in the treatment response prediction for rectal cancer patients treated with chemoradiotherapy followed by surgery. The aim of this study is to evaluate the performance [...] Read more.

Background: Recent studies have highlighted the potentialities of a radiobiological parameter, the early regression index (ERI_TCP), in the treatment response prediction for rectal cancer patients treated with chemoradiotherapy followed by surgery. The aim of this study is to evaluate the performance of this parameter in predicting pathological complete response (pCR) in the context of low field MR guided radiotherapy (MRgRT) for cervical cancer (CC). Methods: A total of 16 patients affected by CC were enrolled. All patients underwent a MRgRT treatment, with prescription of 50.6 Gy in 22 fractions. A daily MR acquisition was performed at simulation and on each treatment fraction. Gross tumor volume (GTV) was delineated on the MR images acquired at the following biological effective dose (BED) levels: 14, 28, 42, 54 and 62 Gy. The ERI_TCP was calculated at the different BED levels and its predictive performance was quantified in terms of receiver operating characteristic (ROC) curve. Results: pCR was observed in 11/16 cases. The highest discriminative power of ERI_TCP was reported when a BED value of 28 Gy is reached, obtaining an area under curve (AUC) of 0.84. Conclusion: This study confirmed ERI_TCP as a promising response biomarker also for CC, although further studies with larger cohort of patients are recommended. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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12 pages, 1191 KiB

Open AccessFeature PaperArticle

Combined Use of a Transmission Detector and an EPID-Based In Vivo Dose Monitoring System in External Beam Whole Breast Irradiation: A Study with an Anthropomorphic Female Phantom

by Chiara Arilli, Yannik Wandael, Chiara Galeotti, Livia Marrazzo, Silvia Calusi, Mattia Grusio, Isacco Desideri, Franco Fusi, Angelo Piermattei, Stefania Pallotta and Cinzia Talamonti

Appl. Sci. 2020, 10(21), 7611; https://doi.org/10.3390/app10217611 - 28 Oct 2020

Cited by 4 | Viewed by 3009

Abstract

We evaluate the combined usage of two systems, the Integral Quality Monitor (IQM) transmission detector and SoftDiso software, for in vivo dose monitoring by simultaneous detection of delivery and patient setup errors in whole breast irradiation. An Alderson RANDO phantom was adapted with [...] Read more.

We evaluate the combined usage of two systems, the Integral Quality Monitor (IQM) transmission detector and SoftDiso software, for in vivo dose monitoring by simultaneous detection of delivery and patient setup errors in whole breast irradiation. An Alderson RANDO phantom was adapted with silicon breast prostheses to mimic the female anatomy. Plans with simulated delivery errors were created from a reference left breast plan, and patient setup errors were simulated by moving the phantom. Deviations from reference values recorded by both monitoring systems were measured for all plans and phantom positions. A 2D global gamma analysis was performed in SoftDiso for all phantom displacements. Both IQM signals and SoftDiso R-values are sensitive to small MU variations. However, only IQM is sensitive to jaw position variations. Conversely, IQM is unable to detect patient positioning errors, and the R-value has good sensitivity to phantom displacements. A gamma comparison analysis allows one to determine alert thresholds to detect phantom shifts or relatively large rotations. The combined use of the IQM and SoftDiso allows for fast identification of both delivery and setup errors and substantially reduces the impact of error identification and correction on the treatment workflow. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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12 pages, 670 KiB

Open AccessArticle

Dosimetric Issues Associated with Percutaneous Ablation of Small Liver Lesions with ⁹⁰Y

by Marco D’Arienzo, Anna Sarnelli, Emilio Mezzenga, Laura Chiacchiararelli, Antonino Amato, Massimo Romanelli, Roberto Cianni, Marta Cremonesi and Giovanni Paganelli

Appl. Sci. 2020, 10(18), 6605; https://doi.org/10.3390/app10186605 - 22 Sep 2020

Cited by 3 | Viewed by 2648

Abstract

The aim of the present paper is twofold. Firstly, to assess the absorbed dose in small lesions using Monte Carlo calculations in a scenario of intratumoral injection of ⁹⁰Y (e.g., percutaneous ablation). Secondly, to derive a practical analytical formula for the calculation [...] Read more.

The aim of the present paper is twofold. Firstly, to assess the absorbed dose in small lesions using Monte Carlo calculations in a scenario of intratumoral injection of ⁹⁰Y (e.g., percutaneous ablation). Secondly, to derive a practical analytical formula for the calculation of the absorbed dose that incorporates the absorbed fractions for ⁹⁰Y. The absorbed dose per unit administered activity was assessed using Monte Carlo calculations in spheres of different size (diameter 0.5–20 cm). The spheres are representative of tumor regions and are assumed to be uniformly filled with ⁹⁰Y. Monte Carlo results were compared with the macrodosimetric approach used for dose calculation in liver radioembolization. The results of this analysis indicate that the use of the analytic model provides dose overestimates below 10% for lesions with diameter larger than approximately 2 cm. However, for lesions smaller than 2 cm the analytic model is likely to deviate significantly (>10%) from Monte Carlo results, providing dose overestimations larger than 50% for lesions of 0.5 cm diameter. In this paper an analytical formula derived from MC calculations that incorporates the absorbed fractions for ⁹⁰Y is proposed. In a scenario of intratumoral injection of microspheres, the proposed equation can be usefully employed in the treatment planning of spherical lesions of small size (down to 0.5 cm diameter) providing dose estimates in close agreement with Monte Carlo calculations (maximum deviation below 0.5%). Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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9 pages, 1312 KiB

Open AccessArticle

The Role of Acquisition Angle in Digital Breast Tomosynthesis: A Texture Analysis Study

by Alessandro Savini, Giacomo Feliciani, Michele Amadori, Stefano Rivetti, Marta Cremonesi, Francesco Cesarini, Tiziana Licciardello, Daniela Severi, Valentina Ravaglia, Alessandro Vagheggini, Anna Sarnelli and Fabio Falcini

Appl. Sci. 2020, 10(17), 6047; https://doi.org/10.3390/app10176047 - 31 Aug 2020

Cited by 2 | Viewed by 2390

Abstract

Background: Digital breast tomosynthesis (DBT) systems employ a sophisticated set of acquisition parameters to generate an image set, and the DBT acquisition angle is considered to be one of the most important parameters. The aim of this study was to use texture analysis [...] Read more.

Background: Digital breast tomosynthesis (DBT) systems employ a sophisticated set of acquisition parameters to generate an image set, and the DBT acquisition angle is considered to be one of the most important parameters. The aim of this study was to use texture analysis to assess how the DBT acquisition angle might influence DBT images of breast parenchyma. Methods: Thirty-four patients were selected from a clinical study conducted at IRST Institute. Each patient underwent a dual DBT scan performed with Fujifilm Amulet Innovality (Fujifilm Corp, Tokyo, Japan) in standard (ST, angular range = 15°) and high-resolution (HR, angular range = 40°) modalities. Texture analysis was applied on the paired dataset using histogram-based features and gray level co-occurrence matrix (GLCM) features. Wilcoxon-signed rank and Pearson-rank tests were used to assess the statistical differences and correlations between extracted features. Results: The DBT acquisition angle did not affect histogram-based features, whereas there was a significant difference in five GLCM features (p < 0.05) between DBT images generated with 15° and 40° acquisition angles. Correlation analysis showed that two GLCM features were not correlated at a p < 0.05 significance level. Conclusions: DBT acquisition angle affects the textures extracted from DBT images and this dependence should be considered when establishing baselines for classifiers of malignant tissue. Furthermore, texture analysis could be proposed as a quantitative method for comparing and scoring the contrast of DBT images. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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Review

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27 pages, 3605 KiB

Open AccessReview

Co-Adjuvant Nanoparticles for Radiotherapy Treatments of Oncological Diseases

by Roberta Crapanzano, Valeria Secchi and Irene Villa

Appl. Sci. 2021, 11(15), 7073; https://doi.org/10.3390/app11157073 - 30 Jul 2021

Cited by 18 | Viewed by 3672

Abstract

Nanomedicine is emerging as promising approach for the implementation of oncological methods. In this review, we describe the most recent methods exploiting heavy nanoparticles and hybrid nanomaterials aiming at improving the traditional X-rays-based treatments. High-Z nanoparticles are proposed as radiosensitizers due to their [...] Read more.

Nanomedicine is emerging as promising approach for the implementation of oncological methods. In this review, we describe the most recent methods exploiting heavy nanoparticles and hybrid nanomaterials aiming at improving the traditional X-rays-based treatments. High-Z nanoparticles are proposed as radiosensitizers due to their ability to stop the ionizing radiation and to increase the locally delivered therapeutic dose. Other nanoparticles working as catalysts can generate reactive oxygen species upon X-rays exposure. Thanks to their high toxicity and reactivity, these species promote DNA cancer cells damage and apoptosis. Hybrid nanoparticles, composed by scintillators coupled to organic molecules, are suitable in X-rays activated photodynamic therapy. This work highlights the roles played by the diverse nanoparticles, upon ionizing radiation irradiation, according to their physico-chemical properties, surface functionalization, and targeting strategies. The description of nanoparticle qualities demanded by the oncological nanomedicine is presented in relation to the processes occurring in biological medium when X-ray radiation interacts with heavy nanoparticles, including the scintillation mechanisms, the stopping power amplification, and the disputed modeling of the effective deposit of energy within nanomaterials. The comprehension of these issues in nanomedicine drives the strategies of nanoparticles engineering and paves the way for the development of advanced medical therapies. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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17 pages, 362 KiB

Open AccessReview

Artificial Intelligence and the Medical Physicist: Welcome to the Machine

by Michele Avanzo, Annalisa Trianni, Francesca Botta, Cinzia Talamonti, Michele Stasi and Mauro Iori

Appl. Sci. 2021, 11(4), 1691; https://doi.org/10.3390/app11041691 - 13 Feb 2021

Cited by 36 | Viewed by 9082

Abstract

Artificial intelligence (AI) is a branch of computer science dedicated to giving machines or computers the ability to perform human-like cognitive functions, such as learning, problem-solving, and decision making. Since it is showing superior performance than well-trained human beings in many areas, such [...] Read more.

Artificial intelligence (AI) is a branch of computer science dedicated to giving machines or computers the ability to perform human-like cognitive functions, such as learning, problem-solving, and decision making. Since it is showing superior performance than well-trained human beings in many areas, such as image classification, object detection, speech recognition, and decision-making, AI is expected to change profoundly every area of science, including healthcare and the clinical application of physics to healthcare, referred to as medical physics. As a result, the Italian Association of Medical Physics (AIFM) has created the “AI for Medical Physics” (AI4MP) group with the aims of coordinating the efforts, facilitating the communication, and sharing of the knowledge on AI of the medical physicists (MPs) in Italy. The purpose of this review is to summarize the main applications of AI in medical physics, describe the skills of the MPs in research and clinical applications of AI, and define the major challenges of AI in healthcare. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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Open AccessReview

Medical Applications of the GEMPix

by Johannes Leidner, Fabrizio Murtas and Marco Silari

Appl. Sci. 2021, 11(1), 440; https://doi.org/10.3390/app11010440 - 5 Jan 2021

Cited by 6 | Viewed by 3106

Abstract

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. A continuous flow [...] Read more.

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. A continuous flow of a gas mixture such as Ar:CO₂:CF₄, Ar:CO₂ or propane-based tissue equivalent gas is supplied externally at a rate of 5 L/h. This article reviews the medical applications of the GEMPix. These include relative dose measurements in conventional photon radiation therapy and in carbon ion beams, by which on-line 2D dose images provided a similar or better performance compared to gafchromic films. Depth scans in a water phantom with ¹²C ions allowed measuring the 3D energy deposition and reconstructing the Bragg curve of a pencil beam. Microdosimetric measurements performed in neutron and photon fields allowed comparing dose spectra with those from Tissue Equivalent Proportional Counters and, additionally, to obtain particle track images. Some preliminary measurements performed to check the capabilities as the detector in proton tomography are also illustrated. The most important on-going developments are: (1) a new, larger area readout to cover the typical maximum field size in radiation therapy of 20 × 20 cm²; (2) a sealed and low-pressure version to facilitate measurements and to increase the equivalent spatial resolution for microdosimetry; (3) 3D particle track reconstruction when operating the GEMPix as a Time Projection Chamber. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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