Reducing radiation exposure during spine surgery

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Radiation exposure due to the use of image intensifiers during spine surgery remains a significant source of potential harm for both patients and surgeons with potential long-term health issues such as cancer, suggests Sebastian Decker.

Intraoperative imaging is often mandatory for spine surgery. Accordingly, different studies have concentrated on the issue of radiation in the operating room. While patients are mostly exposed only during a single surgery, doctors and all other operating room staff are exposed regularly for many years, with spine surgeons generally exposed to higher radiation levels compared with the exposure during other orthopaedic surgeries.1

Recently, radiation exposure during spine surgery has been given much attention as a result of the trend towards minimally invasive surgery, in which fluoroscopy guidance is essential, for example during percutaneous pedicle screw placement,2 kyphoplasty3 or minimal invasive interbody fusion techniques.4,5 Radiation exposure has also been analysed for open surgery techniques.

To protect staff members, limits for occupational radiation exposure have been defined for different regions of the body: 50 rem/year for extremities, 50 rem/year for skin, and 15 rem/year for eyes, as well as <5 rem/year in any one year and only 2 rem/year averaged during five years for the whole body (these values may differ slightly in between different countries). Knowledge about the risks of radiation exposure, the use of protective gear and barriers, as well as the relevance of a great distance as to the inverse-square law, are strongly recommended for fluoroscopy users.6 Particular attention should be paid to often unprotected areas such as the axilla or eye. However, 2,700 lateral lumbar interbody fusions could still be performed each year before exceeding occupational dose limits.6

Surgeons are especially exposed to radiation as they stand near its source. Scattered radiation therefore mainly hits the surgeon standing close to the X-ray tube.1 A reversed setup with the radiation source of the image intensifier on the contralateral side reduces scattered radiation for the surgeon (by a factor of six to eight); however, care should also be taken by other people in the operating room.7 They should therefore increase distance to the patient and image intensifier during fluoroscopy to attach value to the inverse-square law. Moreover, adjusting pulsed modes significantly decreases radiation exposure by a factor of six.7 The highest radiation exposure during spine surgery is detected during anteroposterior lumbar spine imaging.7

While operating room staff are exposed to radiation regularly, patients are only exposed during their own surgery. They obviously cannot be protected against X-rays in the same way as operating room staff. Modern techniques like O-arm imaging offer three-dimensional visualisation of the spine intraoperatively and have been proven to increase accuracy during some procedures like posterior stabilisation.8 While staff usually keep sufficient distance or even leave the room, radiation exposure for patients is as described for abdominal computed tomography (CT) scans.9 Therefore the need of three-dimension imaging should be pondered carefully.10 Severe obesity also is a risk factor for high radiation exposure for both patients as well as operating room staff. A higher radiation dose is needed to gain acceptable contrasts for subsequent interpretation of the images, which directly enters the body of the patient. Moreover this results in higher scattered radiation which affects the surgeon and all other medical staff in the operating room.

While the experience of the surgeon is known to reduce the amount of radiation needed intraoperatively, a new technique becoming more popular also helps to decrease intraoperative radiation: the use of navigation software.11 However, it has to be emphasised that a CT scan is needed before the use of this software. The radiation exposure to the surgeon therefore decreases while overall radiation exposure of the patient still remains high.

As a general recommendation, the need for intraoperative radiation should be evaluated well before being applied. All medical staff, especially surgeons, involved in spine surgery with radiation exposure need profound knowledge of how to minimise individual radiation exposure. This includes general knowledge about radiation, of protective gear and also of the handling of the image intensifier being used. A laser, usually available with the image intensifier, can be used to mark the spot on the skin where the quality of imaging will be best, before triggering the radiation to avoid useless radiation. Moreover, the staff member responsible for triggering the radiation beam should announce it before they do so, to ensure that their colleagues are fully aware. The position of the image intensifier on the floor should be marked if the same position is intended to be reached multiple times to receive equal imaging without the need of multiple images to find the intended position for optimal imaging. In my experience, direct sensitisation is most important to best protect everybody involved in a surgery of this kind.


References

  1. Rampersaud YR, Foley KT, Shen AC, et al. Spine 2000: 25(20); 2637–2645.
  2. Spitz SM, Sandhu FA, Voyadzis. Journal of Neurosurgery: Spine 2015; 1–10.
  3. Mroz TE, Yamashita T, Davros WJ, Lieberman IH. J Spinal Disorders & Techniques 2008: 21(2); 96–100.
  4. Bindal RK, Glaze S, Ognoskie M, et al. Journal of Neurosurgery: Spine 2008: 9(6); 570–573.
  5. Yu E, Khan SN. Clinical Orthopaedics and Related Research 2014; 472(6): 1738–1748.
  6. Taher F, Hughes AP, Sama AA, et al. Spine 2013; 38(16): 1386–1392.
  7. Tatsumi RL. International Journal of Spine Surgery 2012: 6; 195–199.
  8. Smith HE, Welsch MD, Sasso RC, Vaccarno AR. The Journal of Spinal Cord Medicine 2008: 31(5); 532–537.
  9. Lange J, Karellas A, Street J. Spine 2013: 38(5); E306–12.
  10. Nelson EM, Monazzam SM, Kim KD. The Spine Journal 2014: 14(12); 2985–2991.
  11. Kapoor S, Sharma R, G. Indian Journal of Orthopaedics 2014: 48(6); 555–561.

Sebastian Decker is an orthopaedic surgeon at the Hannover Medical School, Hannover, Germany

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