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Doss M. Facilitating the End of the Linear No-Threshold Model Era. J Nucl Med 2024; 65:1173-1174. [PMID: 38906558 DOI: 10.2967/jnumed.124.267868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 06/05/2024] [Indexed: 06/23/2024] Open
Abstract
The linear no-threshold (LNT) model, which asserts that any level of ionizing radiation increases cancer risk, has been the basis of global radiation protection policies since the 1950s. Despite ongoing endorsements, a growing body of evidence challenges the LNT model, suggesting instead that low-level radiation exposure might reduce cancer risk, a concept known as radiation hormesis. This editorial examines the persistence of the LNT model despite evidence favoring radiation hormesis and proposes a solution: a public, online debate between proponents of the LNT model and advocates of radiation hormesis. This debate, organized by a government agency like Medicare, would be transparent and thorough, potentially leading to a shift in radiation protection policies. Acceptance of radiation hormesis could significantly reduce cancer mortality rates and streamline radiation safety regulations, fostering medical innovation and economic growth.
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Affiliation(s)
- Mohan Doss
- Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, Pennsylvania
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Okonkwo UC, Ohagwu CC, Aronu ME, Okafor CE, Idumah CI, Okokpujie IP, Chukwu NN, Chukwunyelu CE. Ionizing radiation protection and the linear No-threshold controversy: Extent of support or counter to the prevailing paradigm. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2022; 253-254:106984. [PMID: 36057228 DOI: 10.1016/j.jenvrad.2022.106984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
This study has developed a relationship that categorized radiation protection and allows for a proper, clear, and concise review of the different classifications in terms of principles of protection, dose criteria, categories, fundamental tools, exposure situations, applications and control measures. With the groundwork laid, advances of the linear no-threshold (LNT) model which has attracted attention in the field of radiobiology and epidemiology were examined in detail. Various plausible dose-response relationship scenarios were x-rayed under low-dose extrapolation. Intensive review of factors opposing the LNT model involving radiophobia (including misdiagnosis, alternative surgery/imaging, suppression of ionizing radiation (IR) research); radiobiology (including DNA damage repair, apoptosis/necrosis, senescence protection) and cost issues (including-high operating cost of LNT, incorrect prioritization, exaggeration of LNT impact, risk-to-benefit analysis) were performed. On the other hand, factors supporting the use of LNT were equally examined, they include regulatory bodies' endorsement, insufficient statistical significance, partial DNA repair, variability of irradiated bodies, different latency periods for cancer, dynamic nature of threshold and conflicting interests. After considering the gaps in the scientific investigations that either support or counter the scientific paradigm on the use of LNT model, further research and advocacy is recommended that will ultimately lead to the acceptance of an alternative paradigm by the international regulators.
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Affiliation(s)
- Ugochukwu C Okonkwo
- Department of Mechanical Engineering, Nnamdi Azikiwe University, Awka, Nigeria.
| | - Christopher C Ohagwu
- Department of Radiography and Radiological Sciences, Nnamdi Azikiwe University, Awka, Nigeria
| | - Michael E Aronu
- Department of Radiology, Nnamdi Azikiwe University, Awka, Nigeria
| | - Christian E Okafor
- Department of Mechanical Engineering, Nnamdi Azikiwe University, Awka, Nigeria
| | - Christopher I Idumah
- Department of Polymer and Textile Engineering, Nnamdi Azikiwe University, Awka, Nigeria
| | - Imhade P Okokpujie
- Department of Mechanical and Mechatronic Engineering, Afe-Babalola University, Ado-Ekiti, Nigeria
| | - Nelson N Chukwu
- National Engineering Design Development Institute, Nnewi, Anambra State, Nigeria
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Tsai CJ, Chang KW, Yang BH, Wu PH, Lin KH, Wong CYO, Lee HL, Huang WS. Very-Low-Dose Radiation and Clinical Molecular Nuclear Medicine. LIFE (BASEL, SWITZERLAND) 2022; 12:life12060912. [PMID: 35743943 PMCID: PMC9225609 DOI: 10.3390/life12060912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/13/2022] [Accepted: 06/15/2022] [Indexed: 11/19/2022]
Abstract
Emerging molecular and precision medicine makes nuclear medicine a de facto choice of imaging, especially in the era of target-oriented medical care. Nuclear medicine is minimally invasive, four-dimensional (space and time or dynamic space), and functional imaging using radioactive biochemical tracers in evaluating human diseases on an anatomically configured image. Many radiopharmaceuticals are also used in therapies. However, there have been concerns over the emission of radiation from the radionuclides, resulting in wrongly neglecting the potential benefits against little or any risks at all of imaging to the patients. The sound concepts of radiation and radiation protection are critical for promoting the optimal use of radiopharmaceuticals to patients, and alleviating concerns from caregivers, nuclear medicine staff, medical colleagues, and the public alike.
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Affiliation(s)
- Chi-Jung Tsai
- Department of Nuclear Medicine, Taipei Medical University Hospital, Taipei 110, Taiwan;
| | - Kang-Wei Chang
- Taipei Neuroscience Institute & Laboratory Animal Center, Taipei Medical University, Taipei 110, Taiwan;
| | - Bang-Hung Yang
- Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei 112, Taiwan; (B.-H.Y.); (K.-H.L.)
| | - Ping-Hsiu Wu
- Department of Radiation Oncology, Taipei Medical University Hospital, Taipei 110, Taiwan;
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 110, Taiwan
| | - Ko-Han Lin
- Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei 112, Taiwan; (B.-H.Y.); (K.-H.L.)
| | - Ching Yee Oliver Wong
- Department of Radiology, University of Southern California, Los Angeles, CA 90007, USA;
| | - Hsin-Lun Lee
- Department of Radiation Oncology, Taipei Medical University Hospital, Taipei 110, Taiwan;
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 110, Taiwan
- Correspondence: (H.-L.L.); (W.-S.H.); Tel.: +886-2-737-2181 (ext. 3396) (H.-L.L.); +886-2-2826-4400 (W.-S.H.)
| | - Wen-Sheng Huang
- Department of Nuclear Medicine, Taipei Medical University Hospital, Taipei 110, Taiwan;
- Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei 112, Taiwan; (B.-H.Y.); (K.-H.L.)
- Department of Nuclear Medicine, Cheng-Hsin General Hospital, No. 45, Cheng-Hsin Street, Beitou District, Taipei 112, Taiwan
- Correspondence: (H.-L.L.); (W.-S.H.); Tel.: +886-2-737-2181 (ext. 3396) (H.-L.L.); +886-2-2826-4400 (W.-S.H.)
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Suárez Fernández JP. The downfall of the linear non-threshold model. Rev Esp Med Nucl Imagen Mol 2020; 39:303-315. [PMID: 32693978 DOI: 10.1016/j.remn.2020.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 12/19/2022]
Abstract
The linear non-threshold model (LNTM) is a theoretical dose-response function as a result of extrapolating the late effects of high-dose exposure to ionizing radiation to the low-dose range, but there is great uncertainty about its validity. The acceptance of LNTM as the dominant probabilistic model have survived to the present day and it is actually the cornerstone of current radiation protection policies. In the last decades, advances in molecular and evolutive biology, cancer immunology, and many epidemiological and animal studies have cast serious doubts about the reliability of the NLTM, as well as suggesting alternative models, like the hormetic theory. Considering the given evidences, a discussion between the involved scientific societies and the regulatory commissions is promtly required in order to to reach a redefiniton of theradiation protection basis, as it would be specially crucial in the medical field.
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Affiliation(s)
- J P Suárez Fernández
- Servicio de Medicina Nuclear, Hospital Universitario Central de Asturias, Oviedo, Asturias, España.
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Doss M. Comment on 'Implications of recent epidemiologic studies for the linear nonthreshold model and radiation protection'. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2019; 39:650-654. [PMID: 31125319 DOI: 10.1088/1361-6498/ab076a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- Mohan Doss
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA, 19111 United States of America
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Doss M. Are We Approaching the End of the Linear No-Threshold Era? J Nucl Med 2018; 59:1786-1793. [PMID: 30262515 DOI: 10.2967/jnumed.118.217182] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 09/24/2018] [Indexed: 12/12/2022] Open
Abstract
The linear no-threshold (LNT) model for radiation-induced cancer was adopted by national and international advisory bodies in the 1950s and has guided radiation protection policies worldwide since then. The resulting strict regulations have increased the compliance costs for the various uses of radiation, including nuclear medicine. The concerns about low levels of radiation due to the absence of a threshold have also resulted in adverse consequences. Justification of the LNT model was based on the concept that low levels of radiation increase mutations and that increased mutations imply increased cancers. This concept may not be valid. Low-dose radiation boosts defenses such as antioxidants and DNA repair enzymes. The boosted defenses would reduce the endogenous DNA damage that would have occurred in the subsequent period, and so the result would be reduced DNA damage and mutations. Whereas mutations are necessary for causing cancer, they are not sufficient since the immune system eliminates cancer cells or keeps them under control. The immune system plays an extremely important role in preventing cancer, as indicated by the substantially increased cancer risk in immune-suppressed patients. Hence, since low-dose radiation enhances the immune system, it would reduce cancers, resulting in a phenomenon known as radiation hormesis. There is considerable evidence for radiation hormesis and against the LNT model, including studies of atomic bomb survivors, background radiation, environmental radiation, cancer patients, medical radiation, and occupational exposures. Though Commentary 27 published by the National Council on Radiation Protection and Measurements concluded that recent epidemiologic studies broadly support the LNT model, a critical examination of the studies has shown that they do not. Another deficiency of Commentary 27 is that it did not consider the vast available evidence for radiation hormesis. Other advisory body reports that have supported the LNT model have similar deficiencies. Advisory bodies are urged to critically evaluate the evidence supporting both sides and arrive at an objective conclusion on the validity of the LNT model. Considering the strength of the evidence against the LNT model and the weakness of the evidence for it, the present analysis indicates that advisory bodies would be compelled to reject the LNT model. Hence, we may be approaching the end of the LNT model era.
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Affiliation(s)
- Mohan Doss
- Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, Pennsylvania
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Cardarelli JJ, Ulsh BA. It Is Time to Move Beyond the Linear No-Threshold Theory for Low-Dose Radiation Protection. Dose Response 2018; 16:1559325818779651. [PMID: 30013457 PMCID: PMC6043938 DOI: 10.1177/1559325818779651] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/18/2018] [Accepted: 05/01/2018] [Indexed: 02/03/2023] Open
Abstract
The US Environmental Protection Agency (USEPA) is the primary federal agency responsible for promulgating regulations and policies to protect people and the environment from ionizing radiation. Currently, the USEPA uses the linear no-threshold (LNT) model to estimate cancer risks and determine cleanup levels in radiologically contaminated environments. The LNT model implies that there is no safe dose of ionizing radiation; however, adverse effects from low dose, low-dose rate (LDDR) exposures are not detectable. This article (1) provides the scientific basis for discontinuing use of the LNT model in LDDR radiation environments, (2) shows that there is no scientific consensus for using the LNT model, (3) identifies USEPA reliance on outdated scientific information, and (4) identifies regulatory reliance on incomplete evaluations of recent data contradicting the LNT. It is the time to reconsider the use of the LNT model in LDDR radiation environments. Incorporating the latest science into the regulatory process for risk assessment will (1) ensure science remains the foundation for decision making, (2) reduce unnecessary burdens of costly cleanups, (3) educate the public on the real effects of LDDR radiation exposures, and (4) harmonize government policies with the rest of the radiation scientific community.
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Harbron RW, Chapple CL, O'Sullivan JJ, Lee C, McHugh K, Higueras M, Pearce MS. Suggestion of reduced cancer risks following cardiac x-ray exposures is unconvincing. Eur J Epidemiol 2018; 33:427-428. [PMID: 29605892 PMCID: PMC5945797 DOI: 10.1007/s10654-018-0383-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 03/20/2018] [Indexed: 11/14/2022]
Affiliation(s)
- Richard W Harbron
- Institute of Health and Society, Sir James Spence Institute, Royal Victoria Infirmary, Newcastle University, Newcastle upon Tyne, NE1 4LP, UK. .,NIHR Health Protection Research Unit in Chemical and Radiation Threats and Hazards, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK.
| | - Claire-Louise Chapple
- Regional Medical Physics Department, Freeman Hospital, Newcastle-upon-Tyne Hospitals NHS Trust, Newcastle upon Tyne, NE7 7DN, UK
| | - John J O'Sullivan
- Paediatric Cardiology, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE7 7DN, UK
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kieran McHugh
- Radiology Department, Great Ormond Street Hospital for Children NHS Trust, London, UK
| | - Manuel Higueras
- Basque Center for Applied Mathematics, Alameda de Mazarredo, 14, 48009, Bilbao, Basque Country, Spain
| | - Mark S Pearce
- Institute of Health and Society, Sir James Spence Institute, Royal Victoria Infirmary, Newcastle University, Newcastle upon Tyne, NE1 4LP, UK.,NIHR Health Protection Research Unit in Chemical and Radiation Threats and Hazards, Newcastle University, Newcastle upon Tyne, NE2 4AA, UK
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Reply to 'Comment on '30 years follow-up and increased risks of breast cancer and leukaemia after long-term low-dose-rate radiation exposure''. Br J Cancer 2018; 118:e10. [PMID: 29438369 PMCID: PMC5846077 DOI: 10.1038/bjc.2017.490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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