Orthopaedic surgeons are increasingly using X ray based fluoroscopic techniques in the operation theatre or in the fluoroscopy room. Procedures such as kyphoplasty, vertebroplasty, deformity correction, pelvic fixation, intramedullary inter-locking nails and CT guided biopsies require radiation exposure. The overall use of radiation in procedures performed by orthopaedic surgeons is not as much as that used by interventional cardiologists. However, the lack of training in radiation protection among orthopaedic surgeons remains a problem.
No. The radiation doses delivered to patients in most orthopaedic procedures under normal conditions will not cause effects such as skin injury, infertility and cataract [deterministic effect]. The typical skin dose in most uro-radiological procedures is less than 1 Gy whereas the threshold for erythema is 2 Gy. However, carcinogenic and genetic effects [stochastic effects] cannot be ruled out, although the probability of such effects can be minimized and is usually small. The typical radiation dose values in terms of dose area product (DAP) are mostly in the range of 0.02 to 20 Gy.cm2. At this level of radiation exposure, probability of radiation effects is much smaller than the benefits that usually occur.
There are patient dependent, equipment dependent and procedure dependent factors.
Patient dependent factors include: body mass or body thickness in the beam, complexity of the lesion and anatomic target structure, previous radiation exposure, radiosensitivity of some patients.
Equipment dependent factors include: Setting of dose rates in pulsed fluoro- and continuous fluoro mode, appropriate quality control, last image hold, acquisition, and virtual collimation.
The main procedure related factors are: number of radiographic frames per run, collimation, fluoroscopic and radiographic acquisition modes, fluoroscopy time, wedge filter, magnification, distance of patient to image receptor (image intensifier or flat panel detector), distance between X ray tube and patient, and tube angulations.
By keeping the X ray tube as far away from the patient as feasible, keeping the image receptor as close to the patient as possible, keeping the foot on the pedal only when essential, reducing the number of images acquired (runs), using the navigation system, collimating the X ray beam, using last image hold, using pulsed fluoroscopy, minimal use of magnification reducing exposure to radiosensitive organs such as the breast and reducing oblique views.
Optimization of protection requires that exposure of patients be the minimum necessary to achieve the required diagnostic and therapeutic objective of the interventional procedure [BSS]. By no means should dose reduction compromise clinical information and outcome. In diagnosis, if the dose is reduced below the minimum necessary, the adverse effects may result in reduced quality and extent of information.
Almost all of the measures to reduce patient dose will also result in a reduction of staff dose.
There are radiation dose limits for staff recommended by the International Commission on Radiological Protection (ICRP) that most countries tend to adopt. Currently the level is 20 mSv/year (actually 100 mSv in 5 years - not to exceed 50 mSv in any one year). This dose limit is based on the calculation of radiation risk over a full working life from the age of 18 years to 65 years (47 years) at the rate of 20 mSv per year, amounting to 20x47= 0.94 Sv and resulting in an excess cancer risk of 1 in 1000. Most orthopaedic surgeons using radiation protection devices and tools will have a radiation dose below typically 2 mSv/year.
Table 1. Approximate dose to the surgeon per procedure (µSv) with 0.5 mm lead apron worn*
|Procedure||Dose to the Surgeon per procedure (µSv)||Screening Time|
*Occupational exposure from common fluoroscopic projections used in orthopedic Surgery [TH].
No. The radiation dose to orthopaedic and trauma surgeons in most routine procedures is much smaller than those performing cardiac interventions.
Very unlikely. Proper use of radiation protection tools and techniques can prevent deterministic effects such as cataract and can avoid any significant increase in probability of cancer risk for many years to cover the full professional life. To date, there have been no reports of radiation induced cataract among orthopaedic surgeons, however such reports do exist for interventional radiologists and cardiologists [VA; CI; VA1].
Yes it is possible. Under optimized conditions when
It is possible to achieve a smaller risk of radiation effects for a full professional life using the ALARA (as low as reasonably achievable) principle. There are situations where protection of patients poses a great challenge, but this is not so much the case for staff, where protection can be reasonably achieved.
Typical values in terms of effective doses are presented in Table 2 below
Table 2. Mean effective doses from Orthopaedic procedures
|Procedure||Mean effective dose (mSv)||Equivalent number of PA chest radiographs (each 0.02 mSv)|
|Other extremities [ME]||0.001||0.05|
|TM joint [HA]||0.012||0.6|
|Cervical Spine [ME]||0.2||10|
|Lumbosacral joint [HA]||0.34||17|
|Upper extremity angiography [BO]||0.56||28|
|Thoracic Spine [ME]||1||50|
|Lumbar Spine [ME]||1.5||75|
|Lower extremity angiography [BO]||3.5||175|
|Thoracic aortography [HA]||4.1||205|
|Peripheral arteriography [HA]||7.1||355|