We appreciate the comments of Dr. Jayasekera and colleagues and acknowledge that our methodology does not reflect a number of conventional techniques employed in the past during the routine use of mobile C-arm fluoroscopy.

In our paper(1), we make note of several dose reducing measures that have been studied over the years and have enabled mobile C-arm operators to produce high quality images while optimizing the overall safety to the patient and operating room staff. These include minimizing exposure time, reducing exposure factors, manipulating the X-ray beam with collimation, maximizing distance from the beam, using protective shielding, and imaging with the C-arm in an inverted orientation relative to the specimen.

In positioning the phantom limb directly on the platform of the image intensifier, the distance from the radiation source to the specimen increases, subsequently reducing the amount of scatter produced. Although many of these measures have been studied using a standard large C-arm unit, the literature reporting similar parameters with the mini C-arm unit is limited. In our experimental design, we attempted to create a “best case scenario” by utilizing known dose reducing techniques to quantify radiation exposure just as a surgeon would likely strive to achieve in a true operating room setting.

In regards to the second portion of the authors’ comments, we point out that at positions of 15 and 25 cm from a focal point on the phantom hand, we found minimal radiation exposure (1-2 mrem) as measured by our dosimeters. These measurements were taken in the plane of the image intensifier. The radiation dosimeter placed directly in the phantom hand, in contrast, recorded substantial exposure levels (181-272 mrem). We did not collect data points between these two locations.

We concur with Jayasekera et al. that many orthopaedic trainees and, for that matter, a great number of mini or large C-arm operators, have a poor understanding of the science behind image intensifier usage. This may lead them to grossly underestimate the potential for high dose radiation exposure if these mobile fluoroscopy units are not used judiciously and with proper intent.

A common error made by novice trainees is the use of the mini C-arm to image larger body parts such as the tibia, femur, humerus, elbow, or shoulder. As the tissue density and cross sectional area of the imaging subject increases, technique factors automatically adjust, in the normal mode, to produce an image with optimal penetration and visual quality. To accommodate for the increased tissue density of a larger body part, technique factors increase by a substantial margin, leading to a much higher radiation exposure rate than may have been encountered by using a large C-arm.

We appreciate the interest in our paper and strive to advance science safety with the commonly used fluoroscopy units.

Reference:

1. Giordano BD, Ryder S, Baumhauer JF, DiGiovanni BF. Exposure to direct and scatter radiation with use of mini-c-arm fluoroscopy. J Bone Joint Surg Am. 2007;89:948-952.

We commend Giordano et al(1) on their excellent work in quantifying the risk of radiation using a mini-C-arm fluoroscopy unit. Their methodology however does not accommodate for measurement of increased radiation exposure when the C-arm is used in the conventional method, with image intensifier vertically above the radiation source(2). Nor does it estimate what the exposure dose would be immediately level to the receiver. Their data however, remains of value to advance the overall safety of fluoroscopy in theatre.

In our as yet unpublished survey of over 75 UK orthopaedic trainees and theatre staff, we found the majority had poor working knowledge of the conventional image intensifier usage and surprisingly little insight into ionising radiation protection issues. Though most orthopaedic trainees in the UK do not ‘push the button’ they do ‘guide’ the radiographer, and supervise the surgical assistant and theatre staff. Therefore the patient, surgical teams and theatre staff may be at risk of exposure. With appropriate training of surgeons the mini-C-arm may be adopted more widely in the NHS (National Health Service), thereby releasing overburdened radiographers from theatre whilst increasing throughput and safety in theatre, as alluded to by White et al(3). However we feel that this can only occur once the recently disbanded ionosing radiation protection course has been re-instigated.

1. Giordano BD, Ryder S, Baumhauer JF, DiGiovanni BF. Exposure to direct and scatter

radiation with use of mini-c-arm fluoroscopy. J Bone Joint Surg Am. 2007;89:948-52.

2. Tremains MR, Georgiadis GM, Dennis MJ. Radiation exposure with use of the

inverted-C-arm technique in upper-extremity surgery. J Bone Joint Surg Am.

2007;89:948-52.

3. White SP. Effect of introduction of mini-C-arm image intensifier in orthopaedic

theatre. Ann R Coll Surg Engl. 2007;89:268-71.

The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.