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Pereira L, Ferreira MT, Lima AGF, Salata C, Ferreira-Machado SC, Lima I, Morandi V, Magalhães LAG. Biological effects induced by doses of mammographic screening. Phys Med 2021; 87:90-98. [PMID: 34130221 DOI: 10.1016/j.ejmp.2021.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 05/31/2021] [Accepted: 06/04/2021] [Indexed: 10/21/2022] Open
Abstract
PURPOSE Mammography is the diagnostic imaging practice used in screening to detect early lesions suspected of malignancy. It uses a low energy X-ray beam in which a low dose in the order of 2-3 mGy is delivered to patient breast cells. However, it has been speculated that it could lead to significant cell damage, when compared to conventional X-ray. We investigated the biological effects of low doses, with mean glandular doses (MGDs) of 2.5 mGy and 2.5 + 2.5 mGy, on mammary cells in vitro. METHODS We used the non-tumorigenic cell line (MCF-10A) and two tumor cells lines (MCF-7 and MDA-MB-231). Colony formation, apoptosis, and double-strand DNA breaks (DSBs) were quantified. RESULTS The selected MGD regimens did not alter the formation of colonies by any of the cell lines. MCF-7 cells exhibited a markedly increase in apoptosis, 24 h after the single-dose protocol; MCF-10A cells underwent apoptosis only after 72 h, with both irradiation regimens, while MDA-MB-231 cells (highly invasive and metastatic) were not susceptible to apoptosis. The detection of γH2AX histone in the nuclei of irradiated cells showed that the double-dose resulted in increase of DSBs, especially in tumor cell lines. CONCLUSIONS Although the health benefits of early breast screening remain indisputable, our future perspective is to better understand the biological basis for the effects of low dose radiation on breast cells and to investigate if and under what conditions there would be a risky situation in repeated mammography screening, in both asymptomatic and symptomatic women.
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Affiliation(s)
- Leslie Pereira
- Department of Medical Physics, Institute of Radiation Protection and Dosimetry (IRD), Av. Salvador Allende, 3773, Barra da Tijuca, Rio de Janeiro, RJ CEP 22783-127, Brazil; Nuclear Engineering Department (DNC), Federal University of Rio de Janeiro (UFRJ), sala 206, Centro de Tecnologia, Av. Horácio Macedo, 2030, Bloco G, Fundão, Rio de Janeiro, RJ CEP 21941-941, Brazil.
| | - Marcella T Ferreira
- Department of Cell Biology, University of the State of Rio de Janeiro (UERJ), Pavilhão Haroldo Lisboa da Cunha, LabAngio, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro, RJ CEP 20550-900, Brazil
| | - Antonio Gilcler F Lima
- Department of Cell Biology, University of the State of Rio de Janeiro (UERJ), Pavilhão Haroldo Lisboa da Cunha, LabAngio, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro, RJ CEP 20550-900, Brazil
| | - Camila Salata
- CGMI/DRS, Brazilian National Nuclear Energy Comission (CNEN), Rua General Severiano, 90, Botafogo, Rio de Janeiro, RJ CEP 22290-901, Brazil.
| | - Samara C Ferreira-Machado
- Department of Radiological Sciences (LCR), State University of Rio de Janeiro (UERJ), Pavilhão Haroldo Lisboa da Cunha, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro, RJ CEP 20550-900, Brazil; Department of General Biology, Federal Fluminense University, Niterói, RJ CEP 21045-900, Brazil
| | - I Lima
- Nuclear Engineering Department (DNC), Federal University of Rio de Janeiro (UFRJ), sala 206, Centro de Tecnologia, Av. Horácio Macedo, 2030, Bloco G, Fundão, Rio de Janeiro, RJ CEP 21941-941, Brazil.
| | - Verônica Morandi
- Department of Cell Biology, University of the State of Rio de Janeiro (UERJ), Pavilhão Haroldo Lisboa da Cunha, LabAngio, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro, RJ CEP 20550-900, Brazil.
| | - Luís A G Magalhães
- Department of Radiological Sciences (LCR), State University of Rio de Janeiro (UERJ), Pavilhão Haroldo Lisboa da Cunha, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro, RJ CEP 20550-900, Brazil
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Kyriakou I, Tremi I, Georgakilas AG, Emfietzoglou D. Microdosimetric investigation of the radiation quality of low-medium energy electrons using Geant4-DNA. Appl Radiat Isot 2021; 172:109654. [PMID: 33676082 DOI: 10.1016/j.apradiso.2021.109654] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 02/17/2021] [Accepted: 02/20/2021] [Indexed: 02/06/2023]
Abstract
The increasing clinical use of low-energy photon and electron sources (below few tens of keV) has raised concerns on the adequacy of the existing approximation of an energy-independent radiobiological effectiveness. In this work, the variation of the quality factor (Q) and relative biological effectiveness (RBE) of electrons over the low-medium energy range (0.1 keV-1 MeV) is examined using several microdosimetry-based Monte Carlo methodologies with input data obtained from Geant4-DNA track-structure simulations. The sensitivity of the results to the different methodologies, Geant4-DNA physics models, and target sizes is examined. Calculations of Q and RBE are based on the ICRU Report 40 recommendations, the Kellerer-Hahn approximation, the site version of the theory of dual radiation action (TDRA), the microdosimetric kinetic model (MKM) of cell survival, and the calculated yield of DNA double strand breaks (DSB). The stochastic energy deposition spectra needed as input in the above approaches have been calculated for nanometer spherical volumes using the different electron physics models of Geant4-DNA. Results are normalized at 100 keV electrons which is here considered the reference radiation. It is shown that in the energy range ~50 keV-1 MeV, the calculated Q and RBE are approximately unity (to within 1-2%) irrespective of the methodology, Geant4-DNA physics model, and target size. At lower energies, Q and RBE become energy-dependent reaching a maximum value of ~1.5-2.5 between ~200 and 700 eV. The detailed variation of Q and RBE at low energies depends mostly upon the adopted methodology and target size, and less so upon the Geant4-DNA physics model. Overall, the DSB yield predicts the highest RBE values (with RBEmax≈2.5) whereas the MKM the lowest RBE values (with RBEmax≈1.5). The ICRU Report 40, Kellerer-Hahn, and TDRA methods are in excellent agreement (to within 1-2%) over the whole energy range predicting a Qmax≈2. In conclusion, the approximation Q=RBE=1 was found to be valid only above ~50 keV whereas at lower energies both Q and RBE become strongly energy-dependent. It is envisioned that the present work will contribute towards establishing robust methodologies to determine theoretically the energy-dependence of radiation quality of individual electrons which may then be used in subsequent calculations involving practical electron and photon radiation sources.
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Affiliation(s)
- Ioanna Kyriakou
- Medical Physics Laboratory, University of Ioannina Medical School, 45110, Ioannina, Greece.
| | - Ioanna Tremi
- DNA Damage Laboratory, Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens (NTUA), Zografou, Athens, Greece
| | - Alexandros G Georgakilas
- DNA Damage Laboratory, Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens (NTUA), Zografou, Athens, Greece
| | - Dimitris Emfietzoglou
- Medical Physics Laboratory, University of Ioannina Medical School, 45110, Ioannina, Greece
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Oliver PAK, Thomson RM. Investigating energy deposition in glandular tissues for mammography using multiscale Monte Carlo simulations. Med Phys 2019; 46:1426-1436. [PMID: 30657190 DOI: 10.1002/mp.13372] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/29/2018] [Accepted: 12/22/2018] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To investigate energy deposition in glandular tissues of the breast on macro- and microscopic length scales in the context of mammography. METHODS Multiscale mammography models of breasts are developed, which include segmented, voxelized macroscopic tissue structure as well as nine regions of interest (ROIs) embedded throughout the breast tissue containing explicitly-modelled cells. Using a 30 kVp Mo/Mo spectrum, Monte Carlo (MC) techniques are used to calculate dose to ∼mm voxels containing glandular and/or adipose tissues, as well as energy deposition on cellular length scales. ROIs consist of at least 1000 mammary epithelial cells and ∼200 adipocytes; specific energy (energy imparted per unit mass; stochastic analogue of the absorbed dose) is calculated within mammary epithelial cell nuclei. RESULTS Macroscopic dose distributions within segmented breast tissue demonstrate considerable variation in energy deposition depending on depth and tissue structure. Doses to voxels containing glandular tissue vary between ∼0.1 and ∼4 times the mean glandular dose (MGD, averaged over the entire breast). Considering microscopic length scales, mean specific energies for mammary epithelial cell nuclei are ∼30% higher than the corresponding glandular voxel dose. Additionally, due to the stochastic nature of radiation, there is considerable variation in energy deposition throughout a cell population within a ROI: for a typical glandular voxel dose of 4 mGy, the standard deviation of the specific energy for mammary epithelial cell nuclei is 85% relative to the mean. Thus, for a glandular voxel dose of 4 mGy at the centre of the breast, corresponding mammary epithelial cell nuclei will receive specific energies up to ∼9 mGy (considering the upper end of the 1σ standard deviation of the specific energy), while a ROI located 2 cm closer to the radiation source will receive specific energies up to ∼40 mGy. Energy deposition within mammary epithelial cell nuclei is sensitive to cell model details including cellular elemental compositions and nucleus size, underlining the importance of realistic cellular models. CONCLUSIONS There is considerable variation in energy deposition on both macro- and microscopic length scales for mammography, with glandular voxel doses and corresponding cell nuclei specific energies many times higher than the MGD in parts of the breast. These results should be considered for radiation-induced cancer risk evaluation in mammography which has traditionally focused on a single metric such as the MGD.
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Affiliation(s)
- Patricia A K Oliver
- Carleton Laboratory for Radiotherapy Physics, Physics Dept., Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Rowan M Thomson
- Carleton Laboratory for Radiotherapy Physics, Physics Dept., Carleton University, Ottawa, ON, K1S 5B6, Canada
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Navin P, Murray AM, Nandikumar K, Waldron R, Tuohy B, Casey M. Shaped-bolus protocol reduces contrast medium volume in abdominal CT while maintaining image quality. Clin Radiol 2016; 72:265.e1-265.e5. [PMID: 27884388 DOI: 10.1016/j.crad.2016.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 09/10/2016] [Accepted: 10/18/2016] [Indexed: 01/29/2023]
Abstract
AIM To prospectively assess whether bolus shaping to exponentially decrease the contrast medium injection rate leads to alteration in image validity or renal function. MATERIALS AND METHODS In this prospective study, patients alternatively received 100 ml contrast medium versus 75 ml via bolus shaping. Image quality was assessed via measurement of attenuation values in the aorta, liver, and spleen and also blinded subjective assessment of image sharpness, low contrast detectability, image noise, and overall quality. Renal function was assessed by change in creatinine levels up to 72 hours post-contrast medium administration. RESULTS Of 190 abdominal computed tomography (CT) studies performed in the 3-month period, 98 received the 75 ml dose. There was no significant difference in renal function or objective image quality with a significant improvement in image sharpness in the 100 ml group. CONCLUSIONS By using bolus-shaping software, it is possible to maintain objective image quality while reducing the contrast medium load to the patient. This has significant implications regarding clinical practice in decreasing cost and risks associated with iodinated contrast media.
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Affiliation(s)
- P Navin
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland.
| | - A M Murray
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland
| | - K Nandikumar
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland
| | - R Waldron
- Department of General Surgery, Mayo General Hospital, Castlebar, County Mayo, Ireland
| | - B Tuohy
- Department of Physics, Saolta University Healthcare Group, Galway, Ireland
| | - M Casey
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland
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Electronic brachytherapy for superficial and nodular basal cell carcinoma: a report of two prospective pilot trials using different doses. J Contemp Brachytherapy 2016; 8:48-55. [PMID: 26985197 PMCID: PMC4793064 DOI: 10.5114/jcb.2016.57531] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 12/18/2015] [Indexed: 12/25/2022] Open
Abstract
Purpose Basal cell carcinoma (BCC) is a very common cancer in the Caucasian population. Treatment aims to eradicate the tumor with the lowest possible functional and aesthetic impact. Electronic brachytherapy (EBT) is a treatment technique currently emerging. This study aims to show the outcomes of two consecutive prospective pilot clinical trials using different radiation doses of EBT with Esteya® EB system for the treatment of superficial and nodular basal cell carcinoma. Material and methods Two prospective, single-center, non-randomized, pilot studies were conducted. Twenty patients were treated in each study with different doses. The first group (1) was treated with 36.6 Gy in 6 fractions of 6.1 Gy, and the second group (2) with 42 Gy in 6 fractions of 7 Gy. Cure rate, acute toxicity, and late toxicity related to cosmesis were analyzed in the two treatment groups. Results In group 1, a complete response in 90% of cases was observed at the first year of follow-up, whereas in group 2, the complete response was 95%. The differences with reference to acute toxicity and the cosmetic results between the two treatment groups were not statistically significant. Conclusions Our initial experience with Esteya® EB system to treat superficial and nodular BCC shows that a dose of 36.6 Gy and 42 Gy delivered in 6 fraction of 7 Gy achieves a 90% and 95% clinical cure rate at 1 year, respectively. Both groups had a tolerable toxicity and a very good cosmesis. The role of EBT in the treatment of BCC is still to be defined. It will probably become an established option for selected patients in the near future.
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Amato E, Asero G, Leotta S, Auditore L, Salamone I, Mannino G, Privitera S, Gueli A. Influence of the X-ray beam quality on the dose increment in CT with iodinated contrast medium. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2016; 24:267-278. [PMID: 27002906 DOI: 10.3233/xst-160551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
BACKGROUND In computed tomography (CT), the image contrast is given by the difference in X-ray attenuation in the various tissues of the patient and contrast media are used to enhance image contrast in anatomic regions characterized by similar attenuation coefficients. OBJECTIVE Aim of the present work is to enlarge the range of applicability of the method previously introduced for organ dosimetry in contrast-enhanced CT, by studying the effects of X-ray beam quality on the parameters of the model. Furthermore, an experimental method for the evaluation of the attenuation properties of iodinated solutions is proposed. METHODS Monte Carlo simulations of anthropomorphic phantoms were carried out to determine a bi-parametrical (a and b) analytical relationship between iodine concentration and dose increase in organs of interest as a function of the tube kilo-voltage peak potential (kVp) and filtration. Experimental measurements of increments in Hounsfield Units (HU) were conducted in several CT scanners, at all the kVp available, in order to determine the parameter γ which relates the HU increment with the iodine mass fraction. A cylindrical phantom that can be filled with iodine solutions provided with an axial housing for a pencil ionization chamber was designed and assembled in order to measure the attenuation properties of iodine solutions under irradiation of a CT scanner and to obtain a further validation of Monte Carlo simulations. RESULTS The simulation-derived parameters of the model, a and b, are only slightly dependent upon the tube kilo-voltage peak potential and filtration, while such scanner-dependent features influence mainly the experimentally-derived γ parameter. Relative dose variations registered by the ionization chamber inside the iodine-filled cylindrical phantom decrease when the X-ray mean energy increases, and reaches about 50% for 10 mg/ml of iodine. CONCLUSIONS The dosimetric method for contrast-enhanced CT can be applied to all CT scanners by adopting average simulative parameters and by carrying out a simple measurement with a series of iodine contrast solutions. The novel experimental methodology introduced can provide a direct measurement of iodine attenuation properties.
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Affiliation(s)
- Ernesto Amato
- Department of Biomedical Sciences and of Morphologic and Functional Imaging, Section of Radiological Sciences, University of Messina, Messina, Italy
| | - Grazia Asero
- PH3DRA (Physics for Dating Diagnostic Dosimetry Research and Applications) Laboratories, Department of Physics and Astronomy, University of Catania, Catania, Italy
| | - Salvatore Leotta
- Department of Physics and Earth Sciences, University of Messina, Messina, Italy
| | - Lucrezia Auditore
- Department of Physics and Earth Sciences, University of Messina, Messina, Italy
| | - Ignazio Salamone
- Department of Biomedical Sciences and of Morphologic and Functional Imaging, Section of Radiological Sciences, University of Messina, Messina, Italy
- University Hospital "Policlinico Gaetano Martino", Messina, Italy
| | - Giovanni Mannino
- University Hospital "Policlinico - Vittorio Emanuele", Catania, Italy
| | - Salvatore Privitera
- PH3DRA (Physics for Dating Diagnostic Dosimetry Research and Applications) Laboratories, Department of Physics and Astronomy, University of Catania, Catania, Italy
| | - Anna Gueli
- PH3DRA (Physics for Dating Diagnostic Dosimetry Research and Applications) Laboratories, Department of Physics and Astronomy, University of Catania, Catania, Italy
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White SA, Reniers B, de Jong EEC, Rusch T, Verhaegen F. A comparison of the relative biological effectiveness of low energy electronic brachytherapy sources in breast tissue: a Monte Carlo study. Phys Med Biol 2015; 61:383-99. [DOI: 10.1088/0031-9155/61/1/383] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Muñoz ID, Avila O, Gamboa-deBuen I, Brandan ME. Evolution of the CaF₂:Tm (TLD-300) glow curve as an indicator of beam quality for low-energy photon beams. Phys Med Biol 2015; 60:2135-44. [PMID: 25683355 DOI: 10.1088/0031-9155/60/6/2135] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We study the high- to low- temperature signal ratio (HLTR) of the CaF2:Tm glow curve as a function of beam quality for low-energy photon beams with effective energy between 15.2 and 33.6 keV, generated with W, Mo and Rh anodes. CaF2:Tm dosemeters (TLD-300) were exposed to x-rays and (60)Co gamma-rays. Glow curves were deconvoluted into 7 peaks, using computerized glow curve deconvolution and HLTR was evaluated. Air kerma and dose in water were between 2.1-15.0 mGy and 49.8-373.8 mGy, respectively. All peaks in the glow curve showed a linear response with respect to air kerma and dose in water. HLTR values decreased monotonically between 1.029 ± 0.010 (at 15.2 keV) and 0.821 ± 0.011 (33.6 keV), and no effects due to the use of different anode/filter combinations were observed. The results indicate a relatively high value of HLTR (about 1 for 17 keV effective energy, or 3 keV μm(-1) track-average LET) and a measurable dependence on the photon beam quality. Comparison of these photon data with HLTR for ions shows good quantitative agreement. The reported evolution of the CaF2:Tm glow curve could facilitate the estimation of the effective energy of unknown photon fields by this technique.
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Affiliation(s)
- I D Muñoz
- Instituto de Física, Universidad Nacional Autónoma de México, 04510 DF, Mexico
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Mills CE, Thome C, Koff D, Andrews DW, Boreham DR. The Relative Biological Effectiveness of Low-Dose Mammography Quality X Rays in the Human Breast MCF-10A Cell Line. Radiat Res 2015; 183:42-51. [DOI: 10.1667/rr13821.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Abolfath RM, Carlson DJ, Chen ZJ, Nath R. A molecular dynamics simulation of DNA damage induction by ionizing radiation. Phys Med Biol 2013; 58:7143-57. [DOI: 10.1088/0031-9155/58/20/7143] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Can contrast media increase organ doses in CT examinations? A clinical study. AJR Am J Roentgenol 2013; 200:1288-93. [PMID: 23701066 DOI: 10.2214/ajr.12.8958] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The purpose of this article is to quantify the CT radiation dose increment in five organs resulting from the administration of iodinated contrast medium. MATERIALS AND METHODS Forty consecutive patients who underwent both un-enhanced and contrast-enhanced thoracoabdominal CT were included in our retrospective study. The dose increase between CT before and after contrast agent administration was evaluated in the portal phase for the thyroid, liver, spleen, pancreas, and kidneys by applying a previously validated method. RESULTS An increase in radiation dose was noted in all organs studied. Average dose increments were 19% for liver, 71% for kidneys, 33% for spleen and pancreas, and 41% for thyroid. Kidneys exhibited the maximum dose increment, whereas the pancreas showed the widest variance because of the differences in fibro-fatty involution. Finally, thyroids with high attenuation values on unenhanced CT showed a lower Hounsfield unit increase and, thus, a smaller increment in the dose. CONCLUSION Our study showed an increase in radiation dose in several parenchymatous tissues on contrast-enhanced CT. Our method allowed us to evaluate the dose increase from the change in attenuation measured in Hounsfield units. Because diagnostic protocols require multiple acquisitions after the contrast agent administration, such a dose increase should be considered when optimizing these protocols.
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El Naqa I, Pater P, Seuntjens J. Monte Carlo role in radiobiological modelling of radiotherapy outcomes. Phys Med Biol 2012; 57:R75-97. [PMID: 22571871 DOI: 10.1088/0031-9155/57/11/r75] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Radiobiological models are essential components of modern radiotherapy. They are increasingly applied to optimize and evaluate the quality of different treatment planning modalities. They are frequently used in designing new radiotherapy clinical trials by estimating the expected therapeutic ratio of new protocols. In radiobiology, the therapeutic ratio is estimated from the expected gain in tumour control probability (TCP) to the risk of normal tissue complication probability (NTCP). However, estimates of TCP/NTCP are currently based on the deterministic and simplistic linear-quadratic formalism with limited prediction power when applied prospectively. Given the complex and stochastic nature of the physical, chemical and biological interactions associated with spatial and temporal radiation induced effects in living tissues, it is conjectured that methods based on Monte Carlo (MC) analysis may provide better estimates of TCP/NTCP for radiotherapy treatment planning and trial design. Indeed, over the past few decades, methods based on MC have demonstrated superior performance for accurate simulation of radiation transport, tumour growth and particle track structures; however, successful application of modelling radiobiological response and outcomes in radiotherapy is still hampered with several challenges. In this review, we provide an overview of some of the main techniques used in radiobiological modelling for radiotherapy, with focus on the MC role as a promising computational vehicle. We highlight the current challenges, issues and future potentials of the MC approach towards a comprehensive systems-based framework in radiobiological modelling for radiotherapy.
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Affiliation(s)
- Issam El Naqa
- Department of Oncology, Medical Physics Unit, Montreal, QC, Canada.
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Bernal MA, deAlmeida CE, David M, Pires E. Estimation of the RBE of mammography-quality beams using a combination of a Monte Carlo code with a B-DNA geometrical model. Phys Med Biol 2011; 56:7393-403. [DOI: 10.1088/0031-9155/56/23/004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Relative biological effectiveness (RBE) compares the severity of damage induced by a radiation under test at a dose D relative to the reference radiation D(x) for the same biological endpoint. RBE is an important parameter in estimation of risk from exposure to ionizing radiation (IR). The present work provides a review of the recently published data and the knowledge of the RBE of low energy electrons and photons. The review presents RBE values derived from experimental data and model calculations including cell inactivation, chromosome aberration, cell transformation, micronuclei formation and induction of double-strand breaks. Biophysical models, including physical features of radiation track, and microdosimetry parameters are presented, analysed and compared with experimental data. The biological effects of low energy electrons and photons are of particular interest in radiation biology as these are strongly absorbed in micrometer and sub-micrometer layers of tissue. RBE values not only depend on the electron and photon energies but also on the irradiation condition, cell type and experimental conditions.
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Affiliation(s)
- Hooshang Nikjoo
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
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Reniers B, Liu D, Rusch T, Verhaegen F. Calculation of relative biological effectiveness of a low-energy electronic brachytherapy source. Phys Med Biol 2008; 53:7125-35. [PMID: 19033642 DOI: 10.1088/0031-9155/53/24/008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Low-energy x-rays are known to have a higher relative biological effectiveness (RBE) than higher energy photons such as the gamma rays from 192Ir and 60Co. In this work the initial yield of single- and double-strand DNA breaks (SSB and DSB) and the RBE was estimated for a novel electronic brachytherapy source (EBS), emitting 40-50 kVp photons. An EGSnrc Monte Carlo model of the source was used in combination with the 'Monte Carlo damage simulation' program (Semenenko and Stewart 2004 Radiat. Res. 161 451-57; 2006 Phys. Med. Biol. 51 1693-706). The results indicate a substantially reduced SSB yield and increased DSB yield for the EBS compared to 60Co or 192Ir, leading to an enhanced RBE by 40-50%. The RBE estimate for the low-energy x-ray EBS was found to be very similar to the low-energy gamma ray brachytherapy isotope 125I. Biological damage was estimated in several human tissues: muscle, breast, calcified breast and cortical bone. SSB and DSB yields were similar in all media, except in bone. These findings should be taken into account if the EBS is intended to replace brachytherapy with the commonly used 192Ir isotope.
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Affiliation(s)
- Brigitte Reniers
- Medical Physics Department, McGill University, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Québec, H3G 1A4, Canada
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Mestres M, Caballín MR, Barrios L, Ribas M, Barquinero JF. RBE of X Rays of Different Energies: A Cytogenetic Evaluation by FISH. Radiat Res 2008; 170:93-100. [DOI: 10.1667/rr1280.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Accepted: 02/27/2008] [Indexed: 11/03/2022]
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Lehnert A, Lessmann E, Pawelke J, Dörr W. RBE of 25 kV X-rays for the survival and induction of micronuclei in the human mammary epithelial cell line MCF-12A. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2006; 45:253-60. [PMID: 16960687 DOI: 10.1007/s00411-006-0062-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 08/03/2006] [Indexed: 05/11/2023]
Abstract
The broad application of low energy X-rays below about 50 keV in radiation therapy and diagnostics and especially in mammography substantiates the precise determination of their relative biological effectiveness (RBE). A quality factor of 1 is stated for photons of all energies in the International Commission on Radiological Protection Recommendations. However, the RBE of low-energy X-rays compared to high-energy photons was found to be dependent on photon energy, cell line and endpoints studied, hence varying from less than one up to about four. In the present study, the human mammary epithelial cell line MCF-12A has been chosen due to the implementation of the results in the estimation of risk from mammography procedures. The RBE of 25 kV X-rays (W anode, 0.3 mm Al filter) relative to 200 kV X-rays (W anode, 0.5 mm Cu filter) was determined for clonogenic survival in the dose range 1-10 Gy and micronuclei (MN) induction in the range 0.5-3.5 Gy. The RBE for clonogenic survival was found to be significantly higher than 1 for surviving fractions in the range 0.005<S<0.2. The RBE decreased with increasing survival, with an RBE0.1 at 10% survival of 1.13+/-0.03. The effectiveness of soft X-rays for MN induction was found to be 1.40+/-0.07 for the fraction of binuclear cells (BNC) with MN and 1.44+/-0.17 for the number of MN per BNC. In contrast, the RBE determined from the number of MN per MN-bearing BNC was found to be 1.08+/-0.32. This indicates that the effectiveness of 25 kV X-rays results from an increase in the number of damaged cells, which, however, do not have higher number of MN per cell.
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Affiliation(s)
- Anna Lehnert
- Institute of Nuclear and Hadron Physics, Forschungszentrum Rossendorf, P.O. Box 510119, 01314, Dresden, Germany.
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Reniers B, Verhaegen F. The microdosimetry of low-energy photons in radiotherapy. RADIATION PROTECTION DOSIMETRY 2006; 122:401-3. [PMID: 17287204 DOI: 10.1093/rpd/ncl488] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Low energy photons are more and more in use in clinical practice, for treatment in radiotherapy as well as for imaging purposes. Their relative biological effectiveness is however still debated. In this paper, some microdosimetric parameters have been calculated for different sources: (125)I, (103)Pd, (131)Cs, an electronic brachytherapy source and various clinical mammography X-ray qualities. These parameters have been used to deduce the quality factors as defined in ICRU 40.
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Affiliation(s)
- B Reniers
- Hôpital Maisonneuve-Rosemont, Montréal, Quebec, Canada.
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Lehnert S, Reniers B, Verhaegen F. Relative biologic effectiveness in terms of tumor response of 125I implants compared with 60Co gamma rays. Int J Radiat Oncol Biol Phys 2005; 63:224-9. [PMID: 16111593 DOI: 10.1016/j.ijrobp.2005.05.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 04/01/2005] [Accepted: 05/06/2005] [Indexed: 11/26/2022]
Abstract
PURPOSE To measure the relative biologic effectiveness (RBE) for 125I seeds compared with external beam radiotherapy using a clinically relevant in vivo system. METHODS AND MATERIALS Photon emission from a detailed source model was simulated using the Monte Carlo code MCNP4C, sampling from a 125I spectrum. The mouse RIF-1 tumor was treated with either temporary implant of an 125I seed or with 60Co gamma rays. The tumors were always the same size at the initiation of treatment, and the endpoint was growth inhibition. RESULTS The dose-response curve for both modalities was close to linear and was independent of the initial 125I activity (dose rate) for the range investigated. Calculation of the RBE for tumor response requires assigning a unique value for the tumor dose that is not homogenous but depends on the distance from the 125I source. Because tumor regrowth will depend on the subpopulation of cells that have the greatest probability of survival (i.e., those at the greatest distance from the 125I source), one approach is to use the dose to this population. On this basis, the RBE for 125I compared with 60Co gamma rays is 1.5. If the 125I dose is computed as the average dose to the tumor, corrected for the dose that is wasted as overkill in the cell population closest to the center of the 125I seed, the RBE is 1.4. CONCLUSION The result, an RBE of 1.4-1.5 is similar to findings obtained by other methods, supporting the validity of this approach to derive an RBE with validity in a clinical context.
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Verhaegen F, Reniers B, Deblois F, Devic S, Seuntjens J, Hristov D. Dosimetric and microdosimetric study of contrast-enhanced radiotherapy with kilovolt x-rays. Phys Med Biol 2005; 50:3555-69. [PMID: 16030382 DOI: 10.1088/0031-9155/50/15/005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Kilovolt x-rays are clearly suboptimal compared to MV photon beams for radiotherapy of deep-seated tumours because of the increased attenuation in tissue, causing a rapid dose fall-off. This picture could change drastically when tumours can be labelled with contrast medium, containing high atomic number elements. This causes a significant dose enhancement to the tumour by exploiting the high cross sections for the photo-electric effect for kV x-rays. In this work, we have investigated the dosimetric and microdosimetric characteristics of kV contrast-enhanced radiation therapy (CERT) for different photon energies, contrast-medium concentrations and types (I and Gd). Two idealized patient treatment plans (head and lung) for irradiation with CT-arc beams were calculated. It is shown that the dose enhancement in tumours can be highly significant (up to about sixfold for realistic 80-120 kVp x-ray spectra and an iodine concentration of 50 mg ml-1) but that dose homogeneity in the tumour depends on photon energy, contrast-medium concentration and type, and irradiation scheme. An attempt to optimize the irradiation scheme is discussed. The microdosimetric study of the dose mean lineal energy shows that radiation quality changes in the contrast-medium-labelled region compared to homogeneous tissue are fairly small and limited to 10%. It is concluded that kV-CERT is a promising radiotherapy technique, provided contrast medium can be delivered reliably to tumours.
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Affiliation(s)
- Frank Verhaegen
- Medical Physics Department, McGill University Health Centre, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Québec, H3G 1A4, Canada.
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