Article
Radiology, Nuclear Medicine & Medical Imaging
Mengying Shi, Cynthia F. Chuang, Nataliya Kovalchuk, Karl Bush, Daniel Zaks, Lei Xing, Murat Surucu, Bin Han
Summary: This study validates the small-field dosimetry of the RefleXion X1 system and establishes an accurate MC model. Through measured and simulated data, parameters such as output factors and dose distributions under different field sizes were obtained, demonstrating the reliability and accuracy of the system.
Article
Radiology, Nuclear Medicine & Medical Imaging
Tae Hoon Kim, Hye Jeong Yang, Jae Young Jeong, Thomas Schaarschmidt, Yong Kyun Kim, Hyun-Tai Chung
Summary: This study calculated the volume averaging effect using scintillation detectors based on a gamma knife dose distribution. The results showed that the output factors measured by the scintillation detectors were consistent with a commercial synthetic micro-diamond detector and recent studies.
Article
Radiology, Nuclear Medicine & Medical Imaging
Nikola Segedin, Hrvoje Hrsak, Sanja Dolanski Babic, Slaven Jurkovic
Summary: The purpose of this study is to calculate volume averaging correction factors for detectors used in Gamma Knife's dosimetry and determine its impact on the field output correction factor. Simulations were conducted using an elliptical dose model and compared with Leksell GammaPlan calculations. Volume averaging correction factors were determined for different detectors, and the dominant contribution of volume averaging to the field output correction factor was demonstrated.
JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS
(2023)
Article
Multidisciplinary Sciences
Ali Ameri, Ghazale Geraily, Mehdi Shojaei, Amir Hossein Karimi
Summary: This study investigates the feasibility of using Magnetic Resonance Imaging (MRI) in combination with the Gamma Knife Icon (GKITM) for real-time monitoring during radiosurgery. A Monte Carlo simulation was conducted to examine the effects of the MRI scanner Magnetic Field (MF) on the dose distribution of GKITM. The study found that the MF has a significant impact on the dose distribution, with higher intensities and smaller collimator sizes showing more prominent effects.
JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES
(2023)
Article
Engineering, Multidisciplinary
T. Medjadj, A. I. Ksenofontov, V. A. Klimanov, A. V. Dalechina, Y. S. Kirpichev
Summary: This study validates the penEasy Monte Carlo model for Leksell Gamma Knife Perfexion through experimental measurements, showing excellent agreement between penEasy and EBT3 results. The differences in output factors and dose profiles were found to be minimal, indicating the potential for clinical application in radiotherapy.
INSTRUMENTS AND EXPERIMENTAL TECHNIQUES
(2021)
Article
Radiology, Nuclear Medicine & Medical Imaging
George X. X. Ding, Indra J. J. Das
Summary: This study investigates the validity of the field size definition by FWHM and by MLC/Jaw opening and finds the pros and cons between these two methods to resolve the controversial issue.
Article
Radiology, Nuclear Medicine & Medical Imaging
Yona Choi, Kook Jin Chun, Eun San Kim, Jungbae Bahng, Hye Jeong Yang, Tae Hoon Kim, Gyu Seok Cho, Sang Hyoun Choi, Young Chan Seo, Hyun-Tai Chung
Summary: This study aimed to assess the role and accuracy of k(Qmsr,Q0)(fmsr,fref) values in determining the absorbed dose rates to water in the reference dosimetry of Gamma Knife. The dose rates were measured using three ionization chambers and various correction factors were applied. The study found that the averaged correction factors reduced the variations in dose rates significantly.
Article
Chemistry, Inorganic & Nuclear
Md Abdullah Al Kafi, Mehenna Arib, Akram Al Moussa, Faisal Alzorkany, Mamoun Shehadeh, Mohd Fahmi Mohd Yusof, Belal Moftah
Summary: The dosimetry of small fields is crucial in IMRT and stereotactic radiosurgery, and it faces challenges due to lack of lateral electronic equilibrium, x-ray source occlusion, and detector volume averaging. Tissue-equivalent detectors are recommended to overcome these challenges, but there are ongoing studies and uncertainties. The IAEA and AAPM CoP provides guidelines and recommendations for small field dosimetry, with a focus on CyberKnife system and the use of various detectors.
APPLIED RADIATION AND ISOTOPES
(2023)
Article
Chemistry, Physical
F. Moradi, S. F. Abdul Sani, M. H. Norazri, N. M. Ung, K. S. Almugren, Kh. Rezaee Ebrahim Saraee, D. A. Bradley
Summary: Small field treatments in radiotherapy have become increasingly important for better control of target volume dose and improved therapeutic ratio. However, the dosimetry of small field techniques is more challenging due to the production of high dose areas with rapid dose rate fall off margins. In this study, Monte Carlo simulations were used to investigate the perturbation effect caused by dosimeter size in radiation fields. The results showed that small size silica fibre TL dosimeters have advantages in small field dosimetry, while conventional LiF TLDs produced significant perturbations, especially in small radiation fields.
RADIATION PHYSICS AND CHEMISTRY
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Miguel Lopez-Sanchez, Maria Perez-Fernandez, Eduardo Pardo, Jose M. Fandino, Antonio Teijeiro, Nicolas Gomez-Fernandez, Faustino Gomez, Diego M. Gonzalez-Castano
Summary: This study used Monte Carlo simulation to evaluate the response of the four smallest active volume ionization chambers when measuring SRS cone collimated FFF fields. The IBA RAZOR Nano Chamber was found to be an excellent choice for narrow beam output factor measurement due to its minimum correction requirement and advantages of tiny size and tissue equivalence materials.
PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
S. Dufreneix, J. Bellec, S. Josset, L. Vieillevigne
Summary: A working group of the French medical physicist society was created to collect small field output factors from 23 centers, with standard deviations of mean factors ranging from less than 1.5% to 5%. The data obtained can serve as external cross verification and help minimize systematic errors in determining small field output factors for SRT programs.
PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS
(2021)
Article
Clinical Neurology
Beong Ik Hur, Seong Jin Jin, Gyeong Rip Kim, Jong Hyeok Kwak, Young Ha Kim, Sang Weon Lee, Soon Ki Sung
Summary: This study investigated the validity of the 5th generation Gamma Knife Perfexion's Leksell Gamma plan 10.1.1 system with a modified variable ellipsoid modeling technique (VEMT), showing consistent results. The modified VEMT method can be used as a stable tool for testing and operating the Gamma Knife Perfexion treatment planning system.
JOURNAL OF KOREAN NEUROSURGICAL SOCIETY
(2021)
Article
Radiology, Nuclear Medicine & Medical Imaging
Mohamad Alissa, Klemens Zink, Ralf-Peter Kapsch, Andreas A. A. Schoenfeld, Stephan Frick, Damian Czarnecki
Summary: This study aimed to determine the correction factors kB,Q for ion chambers in the presence of external magnetic fields in high-energy photon fields. The results showed that the magnitude of the correction factor depends on the chamber volume and orientation, and the preferred chamber orientation is when the magnetic field direction and the chamber axis coincide and are perpendicular to the beam direction. The correction factors can be applied in clinical reference dosimetry for existing MRI-linear accelerators.
Article
Oncology
Mari Partanen, Jarkko Niemela, Jarkko Ojala, Jani Keyrilainen, Mika Kapanen
Summary: The study investigated the properties of the Nano chamber for small-field dosimetry using measurements and MC simulations. Results showed that the Nano chamber is suitable for small field profile measurements down to 2 x 2 cm(2) and appropriate for PDD measurements. Correction factors and field output factors determined for the Nano chamber in TrueBeam fields demonstrated good accuracy and consistency.
Article
Radiology, Nuclear Medicine & Medical Imaging
J. Sempau, P. Kazantsev, J. Izewska, L. Brualla
Summary: The IAEA has operated a global postal dosimetry audit program for radiotherapy centers in collaboration with the WHO since 1969. In 2017, a new methodology based on radiophotoluminescent dosimetry was introduced for these audits.
PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS
(2021)
Article
Radiology, Nuclear Medicine & Medical Imaging
P. Kouris, A. Moutsatsos, E. P. Pappas, I Beli, P. Pantelakos, P. Karaiskos, E. Pantelis
Summary: The dose rate distributions delivered to prostate and head & neck cancer patients treated with a helical TomoTherapy system were analyzed. The analysis showed that treatment time and dose rate varied under different treatment planning conditions. Changing field width and pitch settings can affect dose rate and treatment time.
BIOMEDICAL PHYSICS & ENGINEERING EXPRESS
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Georgia Prentou, Eleftherios P. Pappas, Eleni Prentou, Nikolaos Yakoumakis, Chryssa Paraskevopoulou, Efi Koutsouveli, Evaggelos Pantelis, Panagiotis Papagiannis, Pantelis Karaiskos
Summary: The impact of systematic MLC leaf positional uncertainties on the quality of intracranial single-isocenter multi-target VMAT-SRS treatment plans is studied in this research. The study attempts to estimate appropriate tolerance levels and finds that plan quality indices and dose-volume metrics are very sensitive to systematic sub-millimeter leaf positional inaccuracies. Tailoring acceptable and tolerance levels to VMAT-SRS spatial and dosimetric accuracy requirements is necessary.
JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS
(2022)
Article
Engineering, Biomedical
A. Moutsatsos, P. Kouris, M. Zoros, O. Athanasiou, C. Koutsarnakis, P. Pantelakos, E. Pantelis
Summary: This study found that CyberKnife radiosurgery delivers highly inhomogeneous dose rate distributions in the temporo-spatial domain, and demonstrated the impact of treatment time on the biological effect. It was shown that each physical dose iso-surface is associated with a range of BEDslr values, which changes with increasing treatment time.
PHYSICS IN MEDICINE AND BIOLOGY
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Panagiotis Archontakis, Argyris Moutsatsos, Panagiotis Papagiannis, Ioannis Seimenis, Evaggelos Pantelis
Summary: In this study, the imaging dose and scattered radiation in CyberKnife radiosurgery applications were calculated and analyzed. The amount of scattered radiation reaching each detector was found to depend on the size of the imaged anatomical region. For head applications, the maximum organ dose at the nasal bones was 1.5 mGy, and the average dose to the eye lenses was 0.37 mGy. For extracranial applications, the entrance imaging dose was 0.4 mGy. Sequentially acquiring radiograph pairs instead of simultaneous acquisition can reduce scattered radiation. An estimated dose of 3.7 cGy to the eye lenses is assumed for 100 image pair exposures required for treatment completion.
PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS
(2022)
Article
Health Care Sciences & Services
Ekaterini Matsali, Eleftherios P. Pappas, Efrossyni Lyraraki, Georgia Lymperopoulou, Michalis Mazonakis, Pantelis Karaiskos
Summary: This study aims to compare different radiotherapy methods for the preoperative management of rectal carcinoma, with a focus on the risk of radiation-induced second cancer to the bladder and bowel. The analysis of CT scans and radiotherapy contours from 16 patients showed similar risks of bowel cancer for all techniques and patient ages.
JOURNAL OF PERSONALIZED MEDICINE
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Evaggelos Pantelis, Andreas Logothetis, Emmanouil Zoros, Eleftherios P. Pappas, Panagiotis Papagiannis, Ian Paddick, Hakan Nordstrom, George Kollias, Pantelis Karaiskos
Summary: In this study, the accuracy of the LGP-Convolution algorithm was evaluated in scenarios involving bone and/or air inhomogeneities. The results demonstrated excellent agreement between LGP-Convolution calculations and experimental as well as Monte Carlo results of dose to medium. It was confirmed that the LGP-Convolution algorithm reports the dose to medium, and the air inhomogeneity was found to have no clinical significance.
JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Vasiliki Margaroni, Eleftherios P. Pappas, Anastasios Episkopakis, Evaggelos Pantelis, Panagiotis Papagiannis, Nikolas Marinos, Pantelis Karaiskos
Summary: This study develops a Monte Carlo-based framework to determine correction factors for ionization chambers in MR-Linac dosimetry protocols and quality assurance checks. The study also investigates the dependencies of these factors on irradiation setup conditions and explores the impact of small asymmetrical air gaps on detector readings in solid phantoms.
Article
Health Care Sciences & Services
Ioannis Kantemiris, Eleftherios P. P. Pappas, Georgia Lymperopoulou, Dimitrios Thanasas, Pantelis Karaiskos
Summary: This study used Monte Carlo simulations to estimate the relative biological effectiveness (RBE) of various ions for cancer therapy. The results showed that C-12 ions have a higher dose distribution, while Li-7 ions have a lower dose tail. This work contributes to the identification of the most optimal ion beam for cancer treatment.
JOURNAL OF PERSONALIZED MEDICINE
(2023)
Article
Oncology
Anastasia Stergioula, Evaggelos Pantelis, Theodoros Kormas, Georgios Agrogiannis
Summary: Differentiated thyroid carcinomas usually have slow progression and good long-term survival, but distant metastases can occur in locations such as cervical lymph nodes, lungs, and bones. However, skeletal muscle metastases are extremely rare. This report presents a case of a 42-year-old woman with follicular thyroid cancer who had a thigh mass that was initially misdiagnosed as synovial sarcoma. Further analysis confirmed the mass to be a skeletal muscle metastasis from thyroid cancer. This study aims to raise awareness that skeletal muscle metastases can occur in clinical settings, despite their low probability.
FRONTIERS IN ONCOLOGY
(2023)
Review
Oncology
Anastasia Stergioula, Panagiotis Pantelakos, Ioannis Varthalitis, Georgios Agrogiannis, Evaggelos Pantelis
Summary: Primary cardiac angiosarcomas (PCAs) are rare tumors that are typically found in the right atrium. Most patients present with unresectable tumors and a dismal prognosis. In this report, we present the successful management of an unresectable PCA using weekly paclitaxel combined with radiotherapy delivered by a helical TomoTherapy system. Follow-up imaging studies showed remarkable tumor regression, and the patient remains disease-free 12 months post treatment.
CLINICAL AND TRANSLATIONAL RADIATION ONCOLOGY
(2023)
Review
Oncology
Anastasia Stergioula, Stefania Kokkali, Evaggelos Pantelis
Summary: This systematic review examines the treatment outcome of primary cardiac angiosarcoma patients and finds that multimodality treatment including surgery and chemo-radiotherapy offers the greatest survival benefit.
CANCER TREATMENT REVIEWS
(2023)
Article
Engineering, Biomedical
Anastasios Episkopakis, Vasiliki Margaroni, Stamatiki Kanellopoulou, Nikolas Marinos, Efi Koutsouveli, Pantelis Karaiskos, Eleftherios P. Pappas
Summary: This study focuses on the dose-response characterization of optically stimulated luminescence dosimetry (OSLD), with emphasis on 1.5T MR-Linacs. The results show that the dose-response supralinearity in an MR-Linac setting agrees with that in a conventional linac. The signal fading rate of OSLD does not depend on irradiation conditions. The angular dependence of OSLD is more pronounced under the presence of a magnetic field. OSLDs irradiated with and without real-time MR imaging yield the same response. Correction factors for different detector orientations were determined.
PHYSICS IN MEDICINE AND BIOLOGY
(2023)
Meeting Abstract
Oncology
P. Archontakis, P. Papagiannis, I. Seimenis, E. Pantelis
RADIOTHERAPY AND ONCOLOGY
(2022)
