Chiropractors and X-Rays

Decision Making Standards of Care

Considering Trauma, Disease, Degenerative Changes,
Anomalies, and Biomechanics

Weighing Risks Associated with Ionizing Radiation

History has recorded chiropractic-like providers for millennia. In his 1992 book (1), Scott Haldeman, DC, PhD, MD (neurologist, University of California, Irvine), includes a chapter titled “Spinal Manipulation Before Chiropractic.” Written by anthropologist Robert Anderson, MD, PhD, DC, the chapter reviews evidence of the use of spinal manipulation for spinal pain throughout civilization spanning period of 5,000 years.

The modern era of spinal manipulation providers began in 1895, in America, with Daniel David Palmer. Palmer coined the word “chiropractor.” “Chiro,” the Greek word for hand, and “practor” for practitioner. Essentially, for a provider who practices with his hands.

Within a few decades of 1895, states began to license chiropractors.

Today, chiropractors are licensed health care providers. They are licensed by the state in which they practice. To become licensed by the state, chiropractors must meet all educational requirements and pass all state approved or administered examinations. After licensure, chiropractors must continue to keep their license to practice updated, which again requires meeting continuing educational requirements established by the state and the state’s Board of Chiropractic Examiners (or other state board authority).

With the increasing popularity and utilization of chiropractic, the US Department of Education began to formally scrutinize the education of chiropractors. In 1971, the US Department of Education formally recognized the Council on Chiropractic Education (CCE) to establish and accredit chiropractic education. Today (2020), all US chiropractic colleges must be accredited through the CCE.

Although a chiropractic license in one state does not allow that chiropractor to practice in another state, all chiropractors are allowed certain federal benefits, like treating Medicare patients. As a consequence of CCE accreditation, chiropractic “standards of care” are similar throughout most US states.

Licensing boards and other jurisdictions evaluate licensed health care professionals based upon that profession’s “standard of care.” Although the precise language varies somewhat state to state, the essence of the “standard of care” definition for chiropractic is for the chiropractor to behave in a manner consistent with the following:

A chiropractor of ordinary learning, judgement, and skill would or would not do under the same or similar circumstances.

The key word is ordinary. This excludes being judged by others that have advanced degrees, such as in chiropractic orthopedics, chiropractic neurology, or chiropractic radiology, etc.

Chiropractic Standard of Care and X-Rays
Pertinent History

Historically, chiropractic and x-rays developed together. Both were launched in 1895: chiropractic by Daniel David Palmer and x-rays by Wilhelm Conrad Rontgen. Rontgen was awarded the very first Nobel Prize in Physics, in 1901, for his discovery. Some of the earliest applications of Rontgen’s x-rays were spinal x-rays (spinographs), pioneered by the son of Daniel David Palmer, Bartlett Joshua Palmer. The relationship between chiropractic and x-rays continues through today.

Today’s chiropractor has extensive undergraduate education in radiology, and post-graduate certification in radiology is available. Most field practitioner chiropractors frequently attend continuing education classes in radiology. A number of states require continuing education in radiology to maintain an active license to practice. As such, determining if x-rays are necessary has become a component of chiropractic standards of care.

Radiology is woven into the majority of clinical science and technique courses taught in chiropractic college. Leading scientific/medical journals have confirmed the competency of chiropractors in reading/interpreting spinal x-rays (3, 4, 5).

An assessment of the use of x-rays by chiropractors found (6):

• • 74%  of the chiropractors had x-ray facilities in their offices.
  • 71%  used x-rays to screen for contraindications to chiropractic care.
  • 63% used x-rays to assess the possible existence of pathological conditions.
  • 51%  used x-rays to observe/measure altered biomechanics and posture.
  • 27%  used x-rays for medico-legal protection.
  • 84% of the chiropractors refer to medical radiologists and/or to chiropractic radiologists for a formal interpretation of their radiographs.

The decision to take x-rays on a patient is a clinical call by the chiropractor. The decision is a combination of complaint, history, and examination findings. The chiropractor may decide to take x-rays prior to initiating treatment, or defer x-rays to observe a patient’s response to treatment, or decide that x-rays are not clinically required, at least at that time.

Chiropractors take x-rays on patients for a variety of reasons, including:

• • Fracture — Especially if history is consistent with a force that may induce a broken bone.
  • Pathology — This includes infection, malignancy, and benign tumors.
  • Metabolic — This includes diagnosis such as rheumatoid arthritis, ankylosing spondylitis, Otto’s pelvis.
  • Developmental — Examples would include slipped capital femoral epiphysis, congenital hip dislocation, Legg-Calves-Perth’s disease, etc.
  • Degeneration — This would include disc disease, facet arthrosis, spondylosis, central canal stenosis, lateral recess stenosis, etc.
  • Anomalies — This would include block vertebrae, hemi vertebrae, demi vertebrae, Klippel-Feil syndrome, cervical ribs, os odontoideum, lumbosacral transitional segments (sacralization, lumbarization), facet tropism, dysplasia, agenesis, spina bifida, etc.
  • Biomechanics — This would include segmental malpositions, postural distortions, leg length inequality, scoliosis, ligamentous instabilities (stress radiography), etc. Many chiropractors base their adjustive line-of-drive on spinal biomechanical measurements.

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Studies Supporting Chiropractic X-Rays

In 1983, Stephen Kovach and Eldon Huslig published a study in the Journal of Manipulative and Physiological Therapeutics, titled (7):

Prevalence of Diagnoses on the Basis of
Radiographic Evaluation of Chiropractic Cases

The authors showed the results of a review of all the radiographic examinations performed at the National College of Chiropractic Clinic during the 1982 calendar year. They show how these radiographs helped in the diagnosis of musculoskeletal, cardiopulmonary, and/or or abdominal syndromes. They state:

“The use of plain film radiography has long been a staple of the chiropractic profession. Radiographic examinations are a valuable tool in the chiropractic diagnosis of a patient’s condition.”

••••••••••

In 1984, Kovach and Huslig published another study in the Journal of Manipulative and Physiological Therapeutics, titled (8):

Shoulder Pain and Pancoast tumor: A Diagnostic Dilemma

In this study, the authors describe a case of shoulder pain radiating into the arm and ulnar side of the hand. Cervical spine radiographs were exposed. A careful evaluation showed a Pancoast tumor in the apical region of the lung. Pancoast tumors are malignant tumors. The authors note that radiography was necessary to acquire an accurate diagnosis and an appropriate referral.

••••••••••

In 1992, Owens published a study in the Journal of Manipulative and Physiological Therapeutics, titled (9):

Line Drawing Analyses of Static Cervical X-ray Used in Chiropractic

Following an extensive review of the literature on this topic, the author states:

“Reliability studies exist showing that inter- and intra-examiner reliability are sufficient to measure lateral and rotational displacements of C1 to within +/- 1 degree. This amount of error allows objective analysis of upper cervical x-rays to detect changes in the angular positional relationships of radiographic images on the order of those already seen clinically. Methods of cervical analysis that use relative angular measures of skeletal positioning are best able to control the effects of radiographic distortion.”

This study supports the utilization of upper cervical spine radiographs to determine the measurable biomechanics of the atlas’ lateral and rotational displacements.

••••••••••

The Chiropractic Biophysics, Inc., group prides itself on precision x-ray postural analysis of patients, both prior to and following a protocol of structural rehabilitation. Starting in the 1990s they performed a series of studies whose objective was to establish the reliability and validity of their postural radiological measurements. Their blinded radiological analysis was assessed with the help of the Department of Statistics, Temple University, Philadelphia, PA. They were able to prove both the reliability and validity of their x-ray measurement systems for postural analysis (10, 11, 12, 13, 14).

••••••••••

In 2002, a study was published in the journal Spine, titled (15):

Reliability and Validity of Lumbosacral Spine Radiograph Reading
by Chiropractors, Chiropractic Radiologists, and Medical Radiologists

The authors were from the Department of Radiology, Medical Center Alkmaar, Alkmaar, The Netherlands. The authors acknowledge that plain x-rays of the spine are an established part of chiropractic practice. Their study objective was to determine and compare the reliability and validity of contraindications to chiropractic treatment (infections, malignancies, inflammatory spondylitis, and spondylolysis/spondylolisthesis) detected by chiropractors, chiropractic radiologists, and medical radiologists on plain lumbosacral radiographs. Five chiropractors, three chiropractic radiologists and five medical radiologists read a set of 300 blinded lumbosacral radiographs, 50 of which showed an abnormality. The authors concluded:

“All the professional groups could adequately detect contraindications to chiropractic treatment on radiographs. For this indication, there is no reason to restrict interpretation of radiographs to medical radiologists. Good professional relationships between the professions are recommended to facilitate interprofessional consultation in case of doubt by the chiropractors.”

What Are the Risks/Benefits of Exposure
from Diagnostic X-Ray Ionizing Radiation?

Starting in the late 1920s, and especially after the use of atomic weapons at the end of WWII, it was assumed that any exposure to ionizing radiation was harmful (16). This concept is termed the linear no-threshold dose-response to ionizing radiation. However, this concept has recently been challenged from a number of sources.

In 1979, a study was published in the journal Health Physics, titled (17):

A Catalog of Risks

The authors presented an analysis of loss of life expectancy attributed to a number of risk factors, as follows:

These authors conclude that to increase life expectancy, the priorities should be:

• • Reduce the number of unmarried adults.
  • Control overweight problems.
  • Move to a better state, and do not move to a bad state. (Nevada, Mississippi, South Carolina, West Virginia)
  • Less attention should be paid to radiation hazards and catastrophes.

••••••••••

Hormesis is a phenomenon of dose-response relationships in which something that produces harmful biological effects at moderate to high doses may produce beneficial effects at low doses.

Hormesis was well explained in the July 2015 Scientific American by Mark Mattson, PhD (18). Dr. Mark Mattson has a PhD in biology. He is Chief of the Laboratory of Neurosciences at the National Institute on Aging, and Professor of Neuroscience at Johns Hopkins University. He is Editor-in-Chief of Ageing Research Reviews and NeuroMolecular Medicine, a Section Editor for Neurobiology of Aging, and an Associate Editor for Trends in Neurosciences.

In this article, Dr. Mattson states:

“Hormesis is a term used by toxicologists to refer to a biphasic dose response to an environmental agent characterized by a low dose stimulation or beneficial effect and a high dose inhibitory or toxic effect.”

“Thus, a short working definition of hormesis is: a process in which exposure to a low dose of a chemical agent or environmental factor that is damaging at higher doses induces an adaptive beneficial effect on the cell or organism.”

Dr. Mattson explains that hormesis is a fundamental concept in evolutionary biology. He notes, “thousands of published articles include data showing biphasic responses of cells or organisms to chemicals or changing environmental conditions.”

Beginning several decades ago, credible studies authored by serious researchers in respected peer-reviewed journals began pointing out that exposure to low dose radiation, including from medical imaging, were hormetic. Such exposures would activate within the body a series of protective responses, including the activation of the endogenous anti-oxidant array. This up-regulation of endogenous protectors would neutralize damage caused by the radiation exposure (19, 20, 21, 22, 23, 24, 25, 26, 27).

A literature search of the National Library of Medicine using PubMed with the terms “radiation hormesis” locates 428 articles (May 5, 2020).

A central theme from these studies is that the authors are unyielding in their support for the understanding that high doses of radiation exposure are damaging and harmful. They are equally unyielding and insistent in the science that shows that low doses of radiation, including that from medical x-rays are not harmful, but rather hormetic.

The disagreements in the peer reviewed literature pertaining to medical radiation exposure is so contentious that authors and publications have accused the initiators and perpetuators of the linear no-threshold dose-response to ionizing radiation perspective of “scientific misconduct.” (28)

••••••••••

In 2017, an article was published in the Journal of Nuclear Medicine and titled (29):

Subjecting Radiologic Imaging to
the Linear No-Threshold Hypothesis:
A Non Sequitur of Non-Trivial Proportion

A non sequitur is Latin for “it does not follow.” It means “an invalid argument,” or a conclusion that is “fallacious.”

The linear no-threshold hypothesis (LNTH) has been applied to low-dose ionizing radiation for more than 70 years but lacks a valid scientific foundation. Yet, “this hypothesis is the orthodox foundation of radiation protection science, in turn forming the basis of regulations and public policy.” The authors further state:

“Radiologic imaging is claimed to carry an iatrogenic risk of cancer, based on an uninformed commitment to the 70-y-old linear no-threshold hypothesis (LNTH).”

“Credible evidence of imaging-related low-dose carcinogenic risk is nonexistent; it is a hypothetical risk derived from the demonstrably false linear no-threshold hypothesis.”

“The low-dose radiation of medical imaging has no documented pathway to harm.”

The author’s primary criticism of the linear no-threshold hypothesis of low-dose radiation exposure is that its proponents purposefully ignore the theory’s “fatal flaw.” This flaw is that the proponents focus only on molecular damage while ignoring protective, organismal biologic responses. Earth’s life forms have developed adaptive, biologic repair and/or removal responses to radiation damage. Low doses of radiation stimulate these biological protective responses. Yet, high doses of radiation exposure overwhelm and inhibit such protection mechanisms. The authors state:

“The primary linear no-threshold hypothesis fallacy is it excludes this evolutionary biology, ignoring the body’s differing responses to high versus low radiation doses.”

Low-dose chronic radiation exposure is associated with two adaptive cellular responses: enhanced antioxidant defense and increased apoptotic response. The immune system generally keeps cancers in check, and cancers develop mainly when the immune system is suppressed. Low-dose radiation has been shown to stimulate the immune system, causing a reduction in cancer rates.

The authors conclude that there is an unwarranted fear of low-dose radiation. The contemporary attitude towards health care x-ray exposure has resulted in unjustified “radiophobia,” a perspective that is misplaced, wrong, and non-scientific. The authors make a strong argument why such x-ray exposures should not be avoided based upon fear of radiation.

••••••••••

In 2018, a study was published in the journal Dose-Response, and titled (30):

X-Ray Imaging is Essential for Contemporary Chiropractic
 and Manual Therapy Spinal Rehabilitation:
Radiography Increases Benefits and Reduces Risks

The authors argue for the value of spinal x-rays for determining and measuring both postural and segmental mechanical abnormalities. They also argue that spinal x-rays improve diagnosis and reduce inappropriate treatment. Additionally, spinal x-rays can image both cautionary and absolute contraindications to manual therapy.

The authors cite references to support that the radiation dose employed for plain spinal x-rays radiograph is very low, about 100 times below the documented threshold dose for harmful effects. Hence, medical, dental, and chiropractic x-rays must be considered to be safe.

The authors point out the primary influence of x-ray exposure is the genesis of reactive oxygen species (ROS) that have the ability to exert a damaging influence on cellular DNA. However, the quantity of ROS produced by x-rays is minor compared to the very large quantity of ROS that is constantly produced by aerobic metabolism (breathing air). This makes x-ray generated ROS quantity negligible to human health.

Also, all organisms, including humans, have evolved powerful protective mechanisms that prevent, repair, or remove damage in and to cells caused by ROS. Excessively damaged/cancerous cells may be destroyed by immune system mechanisms, preventing the growth and spread of cancerous cells.

The levels of ROS produced by low-dose x-rays sends signals to upregulate many of the biological protection systems against aerobic ROS, other toxins, pathogens, and all damage events. This stimulation produces a range of beneficial effects, including a lower risk of cancer. The authors state:

“Since low doses of radiation stimulate many protective systems, including the immune system, it is very unlikely that low-level radiation causes more damage than benefit.” [underline and italic added]

“Rather than increasing risk, such exposures would likely stimulate the patient’s own protection systems and result in beneficial health effects.”

“A radiograph may in fact stimulate our protective systems, which is a beneficial health effect.”  

These authors argue that clinical practice guidelines should be updated and abandon unfounded bias against patient exposure to spinal x-rays.

The authors of this article are from Chiropractic Biophysics, Inc. Chiropractic Biophysics is a nonprofit research organization that has published more than 200 peer-review scientific articles in a variety of chiropractic, medical, and scientific journals. Their emphasis is on analyzing biomechanical spinal problems and initiating a program of rehabilitation to improve the abnormal spinal findings towards a more normal anatomical pattern with a goal of improving neuromusculoskeletal physiology. The Chiropractic Biophysics group has been the most active and vocal group questioning decades-long standards pertaining to x-ray ionizing radiation exposure safety.

This year (2020), the Chiropractic Biophysics group has published two additional extensive reviews of the literature studies pertaining to the topic of medical x-ray safety, specifically evaluating long-accepted premises (31, 32):

• • The linear no-threshold (LNTH) hypothesis
  • As Low As Reasonably Achievable (ALARA)

These authors note:

• • ALARA is the acronym for “As Low As Reasonably Achievable.” It is a radiation protection concept borne from the linear no-threshold (LNT) hypothesis.
  • “There are no valid data today supporting the use of LNT in the low-dose range, so dose as a surrogate for risk in radiological imaging is not appropriate, and therefore, the use of the ALARA concept is obsolete.”
  • “Continued use of an outdated and erroneous principle unnecessarily constrains medical professionals attempting to deliver high-quality care to patients by leading to a reluctance by doctors to order images, and a resistance from patients/parents to receive images.”
  • ALARA and its continued endorsement of by regulatory bodies propagates “radiophobia.”
  • “The ALARA principle, as used as a radiation protection principle throughout medicine, is scientifically defunct and should be abandoned.”
  • “Ensuing fear-mongering media headlines of iatrogenic cancers from these essential medical diagnostic tools has led the public and medical professionals alike to display escalating radiophobia.”

SUMMARY:

All licensed health care providers, including chiropractors, are judged by the “standard of care.” Often, but not always, the standard of care for chiropractors requires taking (or referring out for) x-rays.

There are many benefits for both the chiropractor and patient to having spinal x-rays to assist in the analysis, diagnosis, and treatment of spinal syndromes. It appears that in the clinical decision making to expose a patient to ionizing radiation, or not, the concepts of linear no-threshold and As Low As Reasonably Achievable are less concerning than once thought. The negative warnings surrounding x-rays appear to be overstated, and they may be nonexistent.

•••••••••

The Chiropractic Impact Report™ is a monthly publication by myself, Dan Murphy, DC. I am a 1978 graduate of Western States Chiropractic College in Portland, OR. I have managed about 10,000 whiplash-injury cases. In the past 32 years, I have taught more than 500 12-hour post graduate continuing education classes pertaining to whiplash and spinal trauma, including 21 years of coordinating a year-long certification program in spine trauma, certified through the International Chiropractic Association. Additionally, I am board certified in chiropractic orthopedics (DABCO), and I am on the faculty at Life Chiropractic College West in Hayward, CA (28 years).

The purpose of The Chiropractic Impact Report™ is to keep you updated as to relevant academic concepts pertaining to whiplash-injured patients. The hope is that the information is useful in terms of enhanced understanding, as well as helping the personal injury attorney deal with insurance claim adjusters and adverse medical experts.

The chiropractor sending you this Report is well versed and trained in these concepts, and can be a valuable asset in personal injury cases in terms of both academics and treatment. I hope that you find this Report and the referring chiropractor a valuable resource.

Sincerely,

Daniel J. Murphy DC, DABCO

REFERENCES:

1. Anderson R; “Spinal Manipulation Before Chiropractic” in Principles and Practice of Chiropractic, Haldeman S; Appleton & Lang; 1992.
2. Martin SC (1993); Chiropractic and the social context of medical technology; Technology and Culture; Vol. 34; No. 4; pp. 808–834.
3. Taylor JA; Clopton P; Bosch E; Miller KA; Marcelis S; Interpretation of abnormal lumbosacral spine radiographs. A test comparing students, clinicians, radiology residents, and radiologists in medicine and chiropractic; Spine; May 15, 1995; Vol. 20; No. 5; pp. 1147-1153.
4. Assendelft WJ, Bouter LM, Knipschild PG, Wilmink JT; Reliability of lumbar spine radiograph reading by chiropractors; Spine; June 1, 1997; Vol. 22; No. 11; pp. 1235-1241.
5. de Zoete A, Assendelft WJ, Algra PR, Oberman WR, Vanderschueren GM, Bezemer PD; Reliability and validity of lumbosacral spine radiograph reading by chiropractors, chiropractic radiologists, and medical radiologists; Spine; September 1, 2002; Vol. 27; No. 17; pp. 1926-1933.
6. Harger BL, Taylor JA, Haas M; Nyiendo J; Chiropractic radiologists: A survey of chiropractors’ attitudes and patterns of use; Journal of Manipulative and Physiological Therapeutics; June 1997; Vol. 20; No. 5; pp. 311-314.
7. Kovach SG; Huslig EL; Prevalence of diagnoses on the basis of radiographic evaluation of chiropractic cases; Journal of Manipulative and Physiological Therapeutics; December 1983; Vol. 6; No. 4; pp. 197-201.
8. Kovach SG; Huslig EL; Shoulder pain and Pancoast tumor: A diagnostic dilemma; Journal of Manipulative and Physiological Therapeutics; March 1984; Vol. 7; No. 1; pp. 25-31.
9. Owens EF; Line drawing analyses of static cervical X ray used in chiropractic; Journal of Manipulative and Physiological Therapeutics; September 1992; Vol. 15; No. 7; pp. 442-449.
10. Troyanovich SJ, Harrison DE, Harrison DD, Holland B, Janik TJ; Further analysis of the reliability of the posterior tangent lateral lumbar radiographic mensuration procedure: concurrent validity of computer-aided X-ray digitization; Journal of Manipulative and Physiological Therapeutics; September 1998; Vol. 21; No. 7; pp. 460-467.
11. Troyanovich SJ, Harrison SO, Harrison DD, Harrison DE, Payne MR, Janik TJ, Holland B; Chiropractic biophysics digitized radiographic mensuration analysis of the anteroposterior lumbopelvic view: a reliability study; Journal of Manipulative and Physiological Therapeutics; June 1999; Vol. 22; No. 5; pp. 309-315.
12. Troyanovich SJ, Harrison DE, Harrison DD, Holland B, Janik TJ; Chiropractic biophysics digitized radiographic mensuration analysis of the anteroposterior cervicothoracic view: a reliability study; Journal of Manipulative and Physiological Therapeutics; September 2000; Vol. 23; No. 7; pp. 476-482.
13. Harrison DE, Holland B, Harrison DD, Janik TJ; Further reliability analysis of the Harrison radiographic line-drawing methods: crossed ICCs for lateral posterior tangents and modified Risser-Ferguson method on AP views; Journal of Manipulative and Physiological Therapeutics; February 2002; Vol. 25; No. 2; pp. 93-98.
14. Harrison DE, Harrison DD, Colloca CJ, Betz J, Janik TJ, Holland B; Repeatability over time of posture, radiograph positioning, and radiograph line drawing: an analysis of six control groups; Journal of Manipulative and Physiological Therapeutics; February 2003; Vol. 26; No. 2; pp. 87-98.
15. de Zoete A, Assendelft WJ, Algra PR, Oberman WR, Vanderschueren GM, Bezemer PD; Reliability and validity of lumbosacral spine radiograph reading by chiropractors, chiropractic radiologists, and medical radiologists; Spine; September 1, 2002; Vol. 27; No. 17; pp. 1926-1933.
16. Calabrese E; Origin of the linearity no threshold (LNT) dose-response concept; Archives of Toxicology; September 2013; Vol. 87; No. 9; pp. 1621-1633.
17. Cohen B, Lee IS; A Catalog of Risks; Health Physics; June 1979; Vol. 36; pp. 707-722.
18. Mattson MP; Toxic Chemicals in Fruits and Vegetables Are What Give Them Their Health Benefits; Scientific American; July 2015; Vol. 313; No. 1.
19. Pollycove M, Feinendegen LE; Molecular biology, epidemiology, and the demise of the linear no-threshold (LNT) hypothesis; C R Acad Sci III; Feb-Mar 1999; Vol. 32; No. 2-3; pp. 197-204.
20. Calabrese EJ, Baldwin LA; Radiation hormesis: the demise of a legitimate hypothesis; Human Experimental Toxicology; January 2000; Vol. 1; No. 1; pp. 76-84.
21. Feinendegen LE, Pollycove M; Biologic responses to low doses of ionizing radiation: detriment versus hormesis. Part 1. Dose responses of cells and tissues; Journal of Nuclear Medicine; July 2001; Vol. 42; No. 7; pp. 17N-27N.
22. Pollycove M, Feinendegen LE; Biologic responses to low doses of ionizing radiation: Detriment versus hormesis. Part 2. Dose responses of organisms; Journal of Nuclear Medicine; September 2001; Vol. 42; No. 9; pp. 26N-32N.
23. Pollycove M, Feinendegen LE; Radiation-induced versus endogenous DNA damage: possible effect of inducible protective responses in mitigating endogenous damage; Human Experimental Toxicology; June 2003; Vol. 22; No. 6; pp. 290-306.
24. Feinendegen LE, Pollycove M, Sondhaus CA; Responses to low doses of ionizing radiation in biological systems; Nonlinearity Biol Toxicology Medicine; July 2004; Vol. 2; No. 3; pp. 143-171.
25. Feinendegen LE, Pollycove M, Neumann RD; Whole-body responses to low-level radiation exposure: new concepts in mammalian radiobiology; Experimental Hematology; April 2007; Vol. 35; No. 4 (Suppl 1); pp. 37-46.
26. Feinendegen LE, Pollycove M, Neumann RD; Low-dose cancer risk modeling must recognize up-regulation of protection; Dose Response; December 10, 2009; Vol. 8; No. 2; pp. 227-52.
27. Calabrese EJ; Flaws in the LNT single-hit model for cancer risk: An historical assessment; Environ Research; October 2017; Vol. 158; pp. 773-788.
28. Calabrese EJ; LNTgate: How scientific misconduct by the U.S. NAS led to governments adopting LNT for cancer risk assessment; Environmental Research; July 2016; Vol. 148; pp. 535-546.
29. Siegel JA, Pennington CW, Sacks B; Subjecting Radiologic Imaging to the Linear No-Threshold Hypothesis: A Non Sequitur of Non-Trivial Proportion; Journal of Nuclear Medicine; January 2017; Vol. 58; No. 1; pp. 1–6.
30. Paul A. Oakley PA, Jerry M. Cuttler JM, Deed E. Harrison DE; X-Ray Imaging is Essential for Contemporary Chiropractic and Manual Therapy Spinal Rehabilitation: Radiography Increases Benefits and Reduces Risks; Dose-Response: An International Journal; April-June 2018; pp. 1-7.
31. Oakley PA, Harrison DE; Death of the ALARA [As Low As Reasonably Achievable] Radiation Protection Principle as Used in the Medical Sector; Dose-Response: An International Journal; April-June 2020; pp. 1-12.
32. Oakley PA, Harrison DE; Are Restrictive Medical Radiation Imaging Campaigns Misguided? It Seems So: A Case Example of the American Chiropractic Association’s Adoption of “Choosing Wisely”; Commentary; Dose-Response: An International Journal; April-June 2020; pp. 12-14.

“Authored by Dan Murphy, D.C.. Published by ChiroTrust^® – This publication is not meant to offer treatment advice or protocols. Cited material is not necessarily the opinion of the author or publisher.”

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