Could posterior-anterior projection cervical spine radiographs improve image quality and dose reduction


  • Rebecca Faulkner Radiology, Bristol Royal Infirmary, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom.
  • Paul Lockwood Canterbury Christ Church University



Cervical Spine, Image Quality, Radiation Dose, Scatter radiation, Phantom study


Introduction: Anterior-posterior (AP) cervical spine X-rays are routine examinations to assess degenerative change, persistent pain and traumatic injuries. Multiple radiosensitive organs lie anteriorly within this anatomical region, increasing the stochastic risk of cancer. If a posterior-anterior (PA) projection was utilised, the radiation dose could potentially be reduced. The hypothesis of this study is to evaluate the change in radiation dose and image quality between AP and PA positions.

Materials and methods: An anthropomorphic phantom was positioned AP erect against a digital radiography (DR) detector with 30 thermoluminescent dosimeters (TLDs) inserted to record the thyroid, breast, ovaries, and testes absorbed radiation dose at an exposure of 66 kV and 8 mAs. The phantom was repositioned PA erect and repeated. Images were assessed against an image quality criteria Likert scale by qualified radiographers. The mean and standard deviations were calculated for dose and image quality and compared using a t-test and Wilcoxon Signed Ranks Test.

Results: The PA erect cervical spine reduced radiation dose to the right thyroid by 92% (44.7 µGy; p=0.00) and the left thyroid by 89% (43.7 µGy; p=0.00), with further reductions in scatter dose to the breasts (0.35-0.45 µGy; p=0.85), ovaries (0.41 µGy; p=0.57), and testes (0.04 µGy; p=0.98). Image quality scores for the end plates, pedicles, joint spaces, spinous and transverse processes, cortical and trabecular bone patterns, and soft tissues were near equivalent (p=0.32).

Conclusion: Data analysis suggests that PA cervical spine positioning for X-rays in the laboratory adheres to as low as reasonably practicable (ALARP) guidance on X-ray examinations to reduce radiation dose to male and female internal organs (thyroid, breast, ovaries) without a reduction in image quality compared to AP positioning. Further research in clinical practice is advised.


NHS England. Diagnostic Imaging Dataset Annual Statistical Release 2019/2020. Diagnostic Imaging Dataset Annual Statistical Release 2019/2020. Available from: [accessed October 4, 2022].

Murphy A. Cervical Spine (AP View). Radiopaedia. Available from: [accessed October 4, 2022].

Ben-Shlomo A., Bartal G., Mosseri M., Avraham B., Leitner Y., Shabat S. Effective dose reduction in spine radiographic imaging by choosing the less radiation-sensitive side of the body. The Spine Journal 2016;16(4):558–63. Doi: 10.1016/j.spinee.2015.12.012.

Cancer Research UK. Cancer Statistics for the UK. Cancer Statistics for the UK. Available from: [accessed October 4, 2022].

Chan CTP., Fung KKL. Dose optimization in pelvic radiography by air gap method on CR and DR systems – A phantom study. Radiography 2015;21(3):214–23. Doi: 10.1016/j.radi.2014.11.005.

UK Government. Ionising Radiation (Medical Exposure) Regulations (IR(ME)R) 2017 (SI 2017/1322), London: HMSO; 2017.

Majeed A., Kanwal A., Naz N. Diagnostic Accuracy of Plain X-ray in Diagnosis of Cervical Spine Fracture, Keeping CT as Gold Standard. Institute of Medical Science 2016;12(3):171–4.

Whitley S., Sloane C., Jefferson G., Holmes K., Anderson C. Clarke’s Pocket Handbook for Radiographers , 13th ed., London: Hodder Arnold; 2010.

Davey E., England A. AP versus PA positioning in lumbar spine computed radiography: Image quality and individual organ doses. Radiography 2015;21(2):188–96. Doi: 10.1016/j.radi.2014.11.003.

Holm T., Palmer PES., Lehtinen E. World Health Organization. Basic Radiological System: Manual of Radiographic Technique, Geneva: World Health Organization; 1986.

Slosar P. Cervical Spine Anatomy. Spine Health . Available from: [accessed October 4, 2022].

Holmes K., Elkington M., Harris P. Clark’s Essential Physics In Imaging For Radiographers. , Lancaster: University of Cumbria, School of Medical Imaging Sciences ; 2013.

Whitley S., Sloane C., Hoadley G., Moore A., Alsop C. Clarke’s Pocket Handbook for Radiographers, 12th ed., London: Hodder Arnold; 2005.

UK Government. The Ionising Radiation (Medical Exposure) Regulations 2017, London: UK Statutory Instruments; 2017.

Landauer. ⅛" x ⅛" x 0.15" TLD-100H . TLD Chip: Single Point Radiation Assessments. Available from: [accessed October 4, 2022].

J. Stratakis AP. Chapter 1 Dosimetry. Radiation Dose Management of Pregnant Patients, Pregnant Staff and Paediatric Patients, IOP Publishing; 2019.

Thermo Electron Corporation. Thermo Fisher Scientific Harshaw TLD Model 5500 Reader with WinREMS Operator’s Manual (5500-W-O-0805-006). , 2005.

Hanna DW. Development and optimization of a thermoluminescent dosimeter (TLD) analyser system for low-dose measurements utilizing photon counting techniques. Kansas State University, Kansas , 1979.

International Commission on Radiological Protection. The 2007 Recommendations of the International Commission on Radiological Protection. Annals of the ICRP 2007;103.

European Guidelines on Quality Criteria for Diagnostic Radiographic Images. European Guidelines on Quality Criteria for Diagnostic Radiographic Images, 1996.

Hedberg EC., Ayers S. The power of a paired t-test with a covariate. Soc Sci Res 2015;50:277–91. Doi: 10.1016/j.ssresearch.2014.12.004.

The British Institute of Radiology. Guidance on using shielding on patients for diagnostic radiology applications, London; 2020.

Cancer Research UK. Risks and Causes of Thyroid Cancer. Risks and Causes of Thyroid Cancer. Available from: [accessed October 4, 2022].

Robinson JB., Ali RM., Tootell AK., Hogg P. Does collimation affect patient dose in antero-posterior thoraco-lumbar spine? Radiography 2017;23(3):211–5. Doi: 10.1016/j.radi.2017.03.012.

Green C., Karnati G., Thomson K., Subramanian A. Lumbar spine radiographs — is it time for widespread adoption of posteroanterior projection? Br J Radiol 2019;92(1103):20190386. Doi: 10.1259/bjr.20190386.

Health and Care Professions Council. Standards of Proficiency - Radiographers, London; 2013.

Stephenson‐Smith B., Neep MJ., Rowntree P. Digital radiography reject analysis of examinations with multiple rejects: an Australian emergency imaging department clinical audit. J Med Radiat Sci 2021;68(3):245–52. Doi: 10.1002/jmrs.468.

Don S., MacDougall R., Strauss K., Moore QT., Goske MJ., Cohen M., et al. Image Gently Campaign Back to Basics Initiative: Ten Steps to Help Manage Radiation Dose in Pediatric Digital Radiography. American Journal of Roentgenology 2013;200(5):W431–6. Doi: 10.2214/AJR.12.9895.

Singh T., Muscroft N., Collier N., England A. A comparison of effective dose and risk for different collimation options used in AP shoulder radiography. Radiography 2022;28(2):394–9. Doi: 10.1016/j.radi.2021.11.007.

Johnston J., Fauber TL. Essentials of radiographic physics and imaging, Elsevier Health Sciences; 2015.

National Institute for Health and Care Excellence. Spinal injury: assessments and initial management, London; 2016.

Head Injury: Assessment and Early Management. National Institute for Health and Care , London; 2021.

Loughman E., Rowan M., Kenny P. Does magnification increase total unsharpness in DR radiography? Physica Medica 2017;42:353. Doi: 10.1016/j.ejmp.2017.05.007.

Chaparian A., Kanani A., Baghbanian M. Reduction of radiation risks in patients undergoing some X-ray examinations by using optimal projections: A Monte Carlo program-based mathematical calculation. J Med Phys 2014;39(1):32. Doi: 10.4103/0971-6203.125500.

Bell D. Radiographic Distortion. Radiopaedia. Available from: [accessed October 4, 2022].

Nunn H. The Cervical Spine. Image Interpretation . Available from: [accessed October 4, 2022].




How to Cite

Faulkner, R., & Lockwood, P. (2022). Could posterior-anterior projection cervical spine radiographs improve image quality and dose reduction . Radiography Open, 8(1), 38–50.




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