Paul A. Oakley1 , Jerry M. Cuttler2, and Deed E. Harrison3
An International Journal
a The Author(s) 2018
Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1559325818781437 journals.sagepub.com/home/dos
To remedy spine-related problems, assessments of X-ray images are essential to determine the spine and postural parameters. Chiropractic/manual therapy realignment of the structure of the spine can address a wide range of pain, muscle weakness, and functional impairments. Alternate methods to assess such spine problems are often indirect and do not reveal the root cause and could result in a significant misdiagnosis, leading to inappropriate treatment and harmful consequences for the patient. Radiography reveals the true condition and alignment of the spine; it eliminates guesswork. Contemporary approaches to spinal rehabilitation, guided by accurate imaging, have demonstrated superiority over primitive treatments. Unfortunately, there are well-meaning but misguided activists who advocate elimination or minimization of exposures in spine radiography. The radiation dose employed for a plain radiograph is very low, about 100 times below the threshold dose for harmful effects. Rather than increasing risk, such exposures would likely stimulate the patient’s own protection systems and result in beneficial health effects. Spine care guidelines need to be revised to reflect the potential benefits of modern treatments and the lack of health risks from low X-ray doses. This would encourage routine use of radiography in manual spine therapy, which differs from common phar- macologic pain relief practice.
Keywords: spine rehabilitation, radiation exposure, X-ray, chiropractic, routine radiography
1 Private Practice, Newmarket, Ontario, Canada
2. Cuttler & Associates Inc, Vaughan, Ontario, Canada 3 CBP NonProfit, Inc, Eagle, Idaho, USA
Received 26 March 2018; received revised 4 May 2018; accepted 15 May 2018
Corresponding Author: Paul A. Oakley, Private Practice, Newmarket, Ontario, Canada L3Y 8Y8. Email: email@example.com
X-Ray Imaging Is Needed for Manual Therapy of the Spine
Chiropractic/manual therapy realignment of the structure of the spine can address a wide range of pain, muscle weakness, and functional impairments resulting from abnormal stresses and strains on the various spinal components including bone, muscles, ligaments, discs, and neural tissue. As shown in Figure 1, essential components in the pathoanatomical etiological mechanisms in human disease revolve around the spinal cord being housed in the spine, and the spinal nerves passing from the spinal cord through openings between the vertebrae to the regional nerves via the peripheral nervous system.1 A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the central nervous system and the body. Thus, spinal deformities or “subluxations” resulting from various types of poor postures (eg, forward head translation, thoracic hyperkyphosis, etc) and spinal deformities (eg, scoliosis, cervical/lumbar kyphosis, etc) exert direct and indirect pressures onto the nerves and cord as well as onto the associated tissues including muscles, bone, ligaments, discs, and so on and thereby disrupt normal function to cause dys- function or “dis-ease” and outright diagnosable pain and illness syndromes (eg, neck pain, low back pain, sciatica, tension headache, migraine, cervical myofascial pain syndrome, fibromyalgia, etc).
Classically, spinal nerve irritation typically involves radicular symptoms (eg, sciatica, cervical radiculopathy), however all
Figure 1. Spinal nerves, typical location (cervical spine).1
of the involved tissues associated with spinal function including the muscles, ligaments, intervertebral discs, facet joints, and so on when irritated beyond some threshold will exert potential axial or localized symptoms (eg, muscle pains, facet syndrome, etc). Thus, spine and postural subluxation deformities may cause various ailments through various anatomical “pain generators,” where the chiropractor and other manual therapists attempt to diagnose, treat, and manage these patients.
Imaging of the spine is an essential element of modern chiropractic and manual therapy.2-10 Radiography of a standing patient provides important spine/posture data, such as segmen- tal and total angles of curvature,11-15 sagittal balance,16 and degenerative processes.17-23 Also shown are relative and absolute contraindications to manual therapy, such as the traditional “red flags” (ie, serious spinal pathology) including cauda equina syndrome, fracture, infection, inflammatory disorders, abdominal aortic aneurism, ligament instabilities, and malignancies, to name the most obvious (these are concerns for all health-care providers). Further, there are specific considerations for the chiropractor/manual therapist planning to apply external forces to a patient’s spine, unrelated to red flags. These include initial postural presentation, such as sagittal balance, spinal contour, anatomical anomalies (cervical rib, lumbar sacralization, congenital fusions, pelvic morphology, etc), and spinal pathologies (osteoarthritic changes).24-26
In response to concerns about radiography-induced “health effects” such as cancer, we will demonstrate that the radiation doses in medical diagnostics, Figure 2, are more than 100 times lower than the measured threshold dose for radiation-induced cancer. A radiograph may in fact stimulate our protective systems, which is a beneficial health effect.
Alternative spine assessment methods, such as photogrammetry and skin contour measuring devices, give vague, unreliable, and invalid information. They do not represent true internal spine geometry.28-30 Alternative imaging, such as by magnetic resonance imaging, is typically performed with the patient supine. This cannot reveal key anatomical features, including sagittal balance and spinal contour parameters.16,31
Figure 2. Doses in medical diagnostics.27 A spinal radiograph delivers a maximum dose of 2-3 mGy.
Only X-rays can detect the precise spinal coupling patterns present (ie, normal lordosis, hypolordosis, and kyphosis) in assessing craniovertebral syndromes,11 such as forward head translation (Figure 3), lumbar spine disorders12,13 (Figure 4), and to discriminate between true scoliosis and pseudo scoliosis32 (Figure 5). The information obtained in these images is clearly very important for the assessment and treatment of spinal disorders by clinicians seeking to realign altered spine configurations in different patient populations.
Several clinical studies have demonstrated that spine rehabilitation programs, customized for the specific patient’s spinal misalignment, provide better patient outcomes versus traditional standardized approaches of the past (and present).2-10
Recently, randomized clinical trials on patients having cervical hypolordosis (but not hyperlordosis) demonstrated that manual therapy methods, using extension-traction methods to increase the lordosis as part of a multimodal rehabilitation program, provide long-term relief in patients suffering from cervical spondylotic radiculopathy, neck pain, and dizziness.2-5 However, patients in control groups who received traditional (standardized) rehabilitation methods were found to have temporary relief that regressed after cessation of treatment.
Figure 3. Forward head translation as shown in posture and in 3 unique lateral cervical radiographs. All 3 X-ray images have about 25 mm of forward head translation. Left: hyperlordosis; middle: hypolordosis; right: kyphosis. Green line is normal alignment;11 red line highlights patient alignment.
Figure 4. Lateral lumbar radiographs. Left: hyperlordosis; middle: hypolordosis; right: upper lumbar kyphosis. Green line is normal alignment;13 red line highlights patient alignment.
Similarly, randomized clinical studies, on patients with lumbar spine hypolordosis (but not hyperlordosis) using extension- traction methods to restore lordosis, have shown long-term relief from low back pain, disability, improved segmental rotation and translation motion, and discogenic lumbosacral radiculopathy (sciatica).6-8 In contrast, control groups treated by conventional, standardized methods were observed to experience only short-term relief that regressed after the treatment ended.
Finally, in the treatment of scoliosis, trials have demonstrated that when comparing 2 matched groups, those receiving customized, scoliosis-specific exercise programs achieved significantly better outcomes (ie, higher quality of life scores, decreased vertebral and trunk rotation angles, and decreased spinal curve deformity angles). Comparison groups receiving conventional, nonspecific “core” exercise programs either had no improvements (ie, stabilization) or slight improvements but less than the customized treatment group.9,10
Radiation Protection Advice Against Radiography
Radiation protection advice to minimize radiation exposures has spread to the chiropractic profession.33-36 Acceptance of recommendations to eliminate, delay, or otherwise constrain radiography would be very detrimental to the quality of the treatment to patients who suffer from spine-related ailments. Radiographs are essential to accurately diagnose the causes of pain, muscle weakness, and impaired movement and to monitor the progression of the changes resulting from the manual therapy. It is very important to examine the basis for the radiation protection recommendation to restrict radiography. Is it based on evidence or ideology?
Immediately after the discoveries of X-rays in 1895 and radioactivity in 1896, X-ray devices and radioactive materials were applied in physics, chemistry, and medicine. Medical practitioners have employed ionizing radiation for imaging and treatment of patients. Low doses of ionizing radiation (LDIR) were used to treat many illnesses extensively until about the late 1950s when a radiation scare was created to stop testing, development, and production of atomic bombs.
Radiologists learned very early that low doses of radiation produced important beneficial health effects; however, they did not understand the mechanism behind the stimulation of the patient’s protective systems. Many thousands of studies have been carried out over the past 120 years and much has been learned. In 1980, Lauriston Taylor, Past President, National
Figure 5. Posture image and anteroposterior lumbar radiographs depicting a left lateral thoracic translation (side shift). Both patients in the radiographs have a 20-mm left lateral shift of T10 off midline. Left patient has a pure left lateral thoracic translation posture, aka “pseudo scoliosis.” Right patient has a true left lumbar scoliosis (vertebral rotation). Green line is vertical; red line highlights patient alignment.
Council on Radiation Protection and Measurements stated, “Collectively, there exists a vast array of facts and general knowledge about ionizing radiation effects on animal and man. It cannot be disputed that the depth and extent of this knowledge is unmatched by that for most of the myriads of other toxic agents known to man.”37 However, an intense controversy continues about LDIR health effects.
Early Radiation Protection
In the very early days, the users of X-rays were unaware that a large radiation dose could cause serious harmful effects. They also had no instruments to measure the radiation. The calibration of X-ray tubes was based on the amount of skin reddening (erythema) produced when the operator placed a hand directly in the X-ray beam. The dose needed to produce erythema is high—if the skin is exposed to 200 kilovolt X-rays at a high dose rate of 300 mGy per minute, then erythema appears after about 20 minutes or 6 Gy of exposure. A third-degree burn occurs after about 110 minutes or about 20 Gy of exposure.38 (For X-rays, the equivalent dose, sieverts [Sv], equals the absorbed dose, gray (Gy). One gray equals 1 joule/kg of tissue.)
Ignorance of the hazards resulted in many injuries. A severe case of radiation burn was published in July 1896. The first dose limit, about 100 mGy per day, was recommended in 1902. It was based on the lowest dose that could be easily detected by a photographic plate. By 1903, animal studies had shown that X-rays could produce cancer. Most vulnerable were skin tissue and blood-forming bone marrow.38
In 1924, Arthur Mutscheller was the first to recommend (to American Roentgen Ray Society) a “tolerance” dose rate for radiation workers, a dose rate that could be tolerated
indefinitely. He observed workers in shielded work areas and estimated that they had received about 1/10 of an erythema dose or 600 mSv per month. He also observed that none of them had shown any signs of injury. While concluding that this was acceptable, he applied a safety factor of 10, thus setting the limit at 1/100 of an erythema dose per month or 700 mSv per year. A tolerance dose was “assumed to be a radiation dose to which the body can be subjected without production of harmful effects.” His paper, “Physical Standards of Protection Against Roentgen Ray Dangers,” was published in 1925. Sievert’s limit was about the same, using a similar approach.38
Subsequent concerns about potential genetic effects of ionizing radiation and risk of cancer resulted in a stepwise reduction in the recommended annual occupational dose limit from 700 to 10 mSv in 1993. A recommended annual public limit of 5 mSv was introduced in 1960 that was reduced in 1990 to 1 mSv. Figure 1 in Inkret et al shows the changes.38
Genetic and Cancer Concerns
Early geneticists began studying the effects of X-rays on organisms. Muller was a eugenicist who was impatient with the slow pace of natural evolution. In his 1927 seminal paper in Science, he lamented about “the extreme infrequency of mutation occurrence under ordinary conditions, and by the general unsuccessfullness of attempts to modify decidedly, and in a sure and detectable way, this sluggish natural mutation rate. . . . for more directly utilitarian purposes . . . ” He irradiated fruit flies with very large doses of X-rays, at a very high dose rate, and mea- sured high germ cell mutation rates.39 The response was related to the square root of the X-ray energy absorbed. Further studies by geneticists and scientific analyses led to a linear dose–response model and concerns about the risk of low-dose radiogenic health effects in humans.
The use of atomic bombs in the Second World War followed by intensive testing, development, and production of nuclear weapons led to strong antinuclear political activity by many scientists. Without any evidence, they linked exposure to radio- active “fallout” or any ionizing radiation, no matter how small, to a risk of “health effects.” Two articles by Calabrese give very detailed descriptions of why and how linearity at low doses became the basis for carcinogen risk assessment in 1956 and the origin of the linear no-threshold (LNT) dose– response concept.40,41 Recently, Calabrese provided additional evidence about how scientific misconduct by the US National Academy of Sciences led to all governments adopting LNT for cancer risk assessment.42 He also summarized the ideological history of cancer risk assessment.43
Health Effects of Low Doses of X-Rays
At high and LDIR, the detailed response mechanisms are complicated and involve all levels of biological organization. About 3/4 of the body is water, so an important effect of X- rays is the production of reactive oxygen species (ROS). While they cause damage by reacting with biomolecules, ROS also send signals to genes throughout the body. Independently of any radiation effects, it is very important to remember that the aerobic metabolism (breathing air) constantly produces a very large concentration of ROS.44-47
Damage of DNA molecules occurs at a very high rate due to natural, internal causes (eg, ROS). To survive in an environment of multiple toxic impacts, all organisms have powerful protective mechanisms that prevent, repair, or remove damage in and to cells. Surviving cells continue to accumulate internally and externally induced DNA mutations and may become cancer cells. These may be destroyed by the immune system to prevent the growth and spread of cancer.48,49
A low dose of X-rays produces a burst of hits and ROS that damage biomolecules, but it also sends signals to upregulate many of the biological protection systems against aerobic ROS, other toxins, pathogens, and all damage events. Such stimulation produces a range of beneficial effects, including a lower risk of cancer.45,48,49 However, exposures above known thresh- old dose levels will inhibit the protection systems resulting in harmful effects, including radiation illness.49-51
Since low doses of radiation stimulate many protective sys- tems, including the immune system,52 it is very unlikely that low-level radiation causes more damage than benefit. Indeed, damage to molecules and cells from low doses can hardly be observed, while protective mechanisms can be readily seen and quantified.49-52
Is There a Risk of Radiogenic Cancer From Radiographs?
Because of the high natural cancer mortality, about 1 in 4, epidemiology with LNT modeling is incapable of showing
Figure 6. Leukemia incidence, from 1950 to 1957 among 97 000 Hiroshima atomic bomb survivors, reveals an apparent dose threshold at about 50 rem or 500 mSv.53
significantly increased radiogenic cancer mortality at doses below about 100 mGy.
Rather, a prevention of cancer may be seen.50 Figure 6 indicates a dose threshold of about 500 mSv for radiation-induced leukemia. Since blood-forming bone marrow cells are most sensitive to ionizing radiation, it is reasonable to expect that the dose thresholds for other types of cancer are higher than this level.53 Concerns about the risk of cancer from chiropractic radiography are baseless because the dose of an X-ray normally does not exceed about 2 to 3 mGy (200-300 mrem) for a lumbar image,27,54,55 which is more than 100 times lower than the dose threshold for radiogenic cancer.
Chiropractic and manual therapy procedures aimed at the realignment of the structure of the spine can address a wide range of pain, muscle weakness, and functional impairments. Radiographic imaging is necessary to deliver acceptable patient care in the practice of contemporary manual therapy of the spine. Concerns about the risk of cancer are baseless because the dose of a chiropractic spinal X-ray is more than 100 times below the dose threshold for radiogenic leukemia. The threshold for other types of cancer is likely higher. Imaging guidelines need to be updated to reflect current radiobiology and scientific evidence.
Declaration of Conflicting Interests
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: P.A.O. was paid by CBP NonProfit, Inc, for writing the manuscript; D.E.H. teaches spine rehabilitation methods and sells products to physicians for patient care that require radiography for biomechanical analysis.
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by funds from CBP NonProfit, Inc.
Paul A. Oakley http://orcid.org/0000-0002-3117-7330
- Wikipedia. Spinal nerve; 2018. https://commons.wikimedia.org/ w/index.php?curid1⁄41675049. Accessed March 16, 2018.
- Moustafa IM, Diab AM, Ahmed A, Harrison DE. The efficacy of cervical lordosis rehabilitation for nerve root function, pain, and segmental motion in cervical spondylotic radiculopathy. Phy- sioTherapy. 2011;97(suppl):846-847.
- Moustafa IM, Diab AA, Taha S, Harrison DE. Addition of a sagittal cervical posture corrective orthotic device to a multimo- dal rehabilitation program improves short- and long-term out- comes in patients with discogenic cervical radiculopathy. Arch Phys Med Rehabil. 2016;97(12):2034-2044.
- Moustafa IM, Diab AA, Harrison DE: The effect of normalizing the sagittal cervical configuration on dizziness, neck pain, and cervicocephalic kinesthetic sensibility: a 1-year randomized con- trolled study. Eur J Phys Rehabil Med. 2017;53(1):57-71.
- Moustafa IM, Diab AAM, Hegazy FA, Harrison DE. Does reha- bilitation of cervical lordosis influence sagittal cervical spine flexion extension kinematics in cervical spondylotic radiculopa- thy subjects? J Back Musculoskelet Rehabil. 2017;30(4):937-941.
- Diab AA, Moustafa IM. Rehabilitation for pain and lumbar seg- mental motion in chronic mechanical low back pain: a rando- mized trial. J Manipulative Physiol Ther. 2012;35(4):246-253.
- Moustafa IM, Diab AA. Extension traction treatment for patients with discogenic lumbosacral radiculopathy: a randomized con- trolled trial. Clin Rehabil. 2012;27(1):51-62.
- DiabAA,MoustafaIM.Theefficacyoflumbarextensiontraction for sagittal alignment in mechanical low back pain. A randomized trial. J Back Musculoskelet Rehabil. 2013;26(2):213-222.
- Noh DK, You JS, Koh JH, et al. Effects of novel corrective spinal technique on adolescent idiopathic scoliosis as assessed by radio- graphic imaging. J Back Musculoskelet Rehabil. 2014;27(3): 331-338.
- Monticone M, Ambrosini E, Cazzaniga D, Rocca B, Ferrante S. Active self-correction and task-oriented exercises reduce spinal deformity and improve quality of life in subjects with mild ado- lescent idiopathic scoliosis. Results of a randomised controlled trial. Eur Spine J. 2014;23(6):1204-1214.
- Harrison DD, Harrison DE, Janik TJ, et al. Modeling of the sagit- tal cervical spine as a method to discriminate hypo-lordosis: results of elliptical and circular modeling in 72 asymptomatic subjects, 52 acute neck pain subjects, and 70 chronic neck pain subjects. Spine. 2004;29(22):2485-2492.
- Chun SW, Lim CY, Kim K, Hwang J, Chung SG. The relation- ships between low back pain and lumbar lordosis: a systematic review and meta-analysis. Spine J. 2017;17(8):1180-1191
- Harrison DD, Cailliet R, Janik TJ, Troyanovich SJ, Harrison DE, Holland B. Elliptical modeling of the sagittal lumbar lordosis and segmental rotation angles as a method to discriminate between normal and low back pain subjects. J Spinal Disord. 1998;11(5): 430-439.
- McAviney J, Schulz D, Bock R, Harrison DE, Holland B. Deter- mining a clinical normal value for cervical lordosis. J Manipula- tive Physiol Ther. 2005;28(3):187-193.
- Keller TS, Colloca CJ, Harrison DE, Harrison DD, Janik TJ. Influence of spine morphology on intervertebral disc loads and stresses in asymptomatic adults: implications for the ideal spine. Spine J. 2005;5(3):297-305.
- LeHuecJC,SaddikiR,FrankeJ,RigalJ,AunobleS.Equilibrium of the human body and the gravity line: the basics. Eur Spine J. 2011;20(suppl 5):558-563.
- Roussouly P, Pinheiro-Franco JL. Biomechanical analysis of the spino-pelvic organization and adaptation in pathology. Eur Spine J. 2011;20(suppl 5):609-618.
- Barrey C, Jund J, Noseda O, Roussouly P. Sagittal balance of the pelvis-spine complex and lumbar degenerative diseases. A com- parative study about 85 cases. Eur Spine J. 2007;16(9): 1459-1467.
- Labelle H, Roussouly P, Berthonnaud E, Dimnet J, O’Brien M. The importance of spino-pelvic balance in L5-S1 developmental spondylolisthesis: a review of pertinent radiologic measurements. Spine. 2005;30(suppl 6):S27-S34.
- Harrison DE, Harrison DD, Janik TJ, Jones EW, Cailliet R, Nor- mand M. Comparison of axial and flexural stresses in lordosis and three buckled modes in the cervical spine. Clin Biomech. 2001; 16(4):276-284.
- Harrison DD, Jones EW, Janik TJ, Harrison DE. Evaluation of flexural stresses in the vertebral body cortex and trabecular bone in three cervical configurations with an elliptical shell model. J Manipulative Physiol Ther. 2002;25(6):391-401.
- Keller TS, Harrison DE, Colloca CJ, Harrison DD, Janik TJ. Prediction of osteoporotic spinal deformity. Spine. 2003;28(5): 455-462.
- Harrison DE, Colloca CJ, Keller TS, Harrison DD, Janik TJ. Anterior thoracic posture increases thoracolumbar disc loading. Eur Spine J. 2005;14:234-242.
- Beck RW, Holt KR, Fox MA, Hurtgen-Grace KL. Radiographic anomalies that may alter chiropractic intervention strategies found in a New Zealand population. J Manipulative Physiol Ther. 2004;27(9):554-559.
- Jenkins H, Zheng X, Bull P. Prevalence of congenital abnormal- ities contraindicating spinal manipulative therapy within a chir- opractic patient population. Chiropr J Aust. 2010;40(2):69-76.
- Young KJ, Aziz A. An account of pathology visible on lumbar spine radiographs of patients attending private chiropractic clinics in the United Kingdom. Chiropr J Aust. 2009;39:63-69.
- Metting N. Ionizing Radiation Dose Ranges (Sievert). Office of Biological and Environmental Research. U.S. Department of Energy. Office of Science. 2010. http://www.dcfpnavymil.org/ Library/tables/DoseRanges.pdf. Accessed March 16, 2018.
- Johnson GM. The correlation between surface measurement of head and neck posture and the anatomic position of the upper cervical vertebrae. Spine. 1998;23(8):921-9
- Stokes IA, Bevins TM, Lunn RA. Back surface curvature and measurement of lumbar spinal motion. Spine. 1987;12(4):355-361.
- Harrison DE, Haas JW, Cailliet R, Harrison DD, Janik TJ, Hol- land B. Concurrent validity of the flexicurve instrument measure- ments: sagittal skin contour of the cervical spine compared to lateral cervical radiographic measurements. J Manipulative Physiol Ther. 2005;28(8):597-603.
- Oakley PA, Harrison DE. Reply to Lumbar lordosis: study of patients with and without low back pain. Clin Anat. 2004;17(4):367.
- Harrison DE, Betz JW, Cailliet R, et al. Radiographic pseudoscoliosis in healthy male subjects following voluntary lateral trans- lation (side glide) of the thoracic spine. Arch Phys Med Rehabil. 2006;87(1):117-22.
- Oakley PA, Harrison DD, Harrison DE, Haas JW. On “phantom risks” associated with diagnostic ionizing radiation: evidence in support of revising radiography standards and regulations in chir- opractic. J Can Chiropr Assoc. 2005;49(4):264-269.
- Bussie`res AE, Ammendolia C, Peterson C, Taylor JA. Ionizing radiation exposure—more good than harm? The preponderance of evidence does not support abandoning current standards and reg- ulations. J Can Chiropr Assoc. 2006;50(2):103-106.
- Oakley PA, Harrison DD, Harrison DE, Haas JW. A rebuttal to chiropractic radiologists’ view of the 50-year-old, linear-no- threshold radiation risk model. J Can Chiropr Assoc. 2006; 50(3):172-181.
- Harrison DE, Harrison DD, Kent C, Betz J. Practicing Chiroprac- tors’ Guidelines for the utilization of plain film X-ray imaging for the biomechanical assessment, characterization, and quantifica- tion of spinal subluxation in Chiropractic Clinical Practice. Prac- ticing Chiropractors’ Committee on Radiology Protocols (PCCRP) (http://www.pccrp.org); 2009:1-386. Falls Church, VA, USA: International Chiropractors Association.
- Taylor LS.Some nonscientific influences on radiation protection standards and practice, the 1980 Sievert lecture. Health Phys. 1980;39(6):851-874. p.852.
- Inkret WC, Meinhold CB, Taschner JC. Radiation and risk—a hard look at the data. A brief history of radiation protection stan- dards. Los Alamos Science. 1995;23:116-123. https://fas.org/sgp/ othergov/doe/lanl/pubs/00326631.pdf. Accessed March 8, 2018.
- Muller HJ. Artificial transmutation of the gene. Science. 1927; 66(1699):84-87.
- Calabrese EJ. The road to linearity: why linearity at low doses became the basis for carcinogen risk assessment. Arch Toxicol. 2009;83(3):203-225.
- Calabrese EJ. Origin of the linearity no threshold (LNT) dose- response concept. Arch Toxicol. 2013;87(9):1621-1633.
- Calabrese EJ.LNTgate: how scientific misconduct by the U.S. NAS led to governments adopting LNT for cancer risk assess- ment. Environ Res. 2016;148:535-546.
- Calabrese EJ. LNTgate: the ideological history of cancer risk assessment. Tox Res Applic. 2017;1:1-3.
- Feinendegen LE. Reactive oxygen species in cell responses to toxic agents. Human Exp Toxicol. 2002;21(2):85-90.
- Pollycove M, Feinendegen LE. Radiation-induced versus endo- genous DNA damage: possible effect of inducible protective responses in mitigating endogenous damage. Human Exp Toxicol. 2003;22(6):290-306.
- Sies H, Berndt C, Jones DP. Oxidative stress. Ann Rev Biochem. 2017;86(7):715-748.
- Sies H, Feinendegen LE. Radiation hormesis: the link to nano- molar hydrogen peroxide. Antioxid Redox Signal. 2017;27(9): 596-598.
- Feinendegen LE, Pollycove M, Neumann RD. Hormesis by low dose radiation effects: low-dose cancer risk modeling must recog- nize up-regulation of protection. In: Baum RP, ed. Therapeutic Nuclear Medicine. Berlin, Heidelberg: Springer. 2012;789-805.
- Pollycove M. Radiobiological basis of low-dose irradiation in prevention and therapy of cancer. Dose-Response. 2006;5(1): 26-38.
- Cuttler JM, Feinendegen LE, Socol Y. Evidence that lifelong low dose rates of ionizing radiation increase lifespan in long- and short-lived dogs. Dose-Response. 2017;15(1):1-6.
- Feinendegen LE, Cuttler JM. Biological effects from low doses and dose rates of ionizing radiation: science in the service of protecting humans, a synopsis. Health Phys. 2018;114(6): 623-626.
- LiuSZ.Cancercontrolrelatedtostimulationofimmunitybylow- dose radiation. Dose Response. 2007;5(1):39-47.
- Cuttler JM, Welsh JS. Leukemia and ionizing radiation revisited. J Leukemia. 2015;3:202. doi:10.4172/2329-6917.1000202. https://www.omicsonline.org/peer-reviewed/leukemia-and-ioniz- ing-radiation-revisited-65327.html.
- Simpson AK, Whang PG, Jonisch A, Haims A, Grauer JN. The radiation exposure associated with cervical and lumbar spine radiographs. J Spinal Disord Tech. 2008;21(6):409-412.
- GiordanoBD,GrauerJN,MillerCP,MorganTL,RechtineGRII. Radiation exposure issues in orthopaedics. J Bone Joint Surg Am. 2011;932(12):e69(1-10).