Surgeon radiation exposure in ESS with balloon catheters

Otolaryngology–Head and Neck Surgery (2009) 140, 834-840

ORIGINAL RESEARCH—SINONASAL DISORDERS

Surgeon radiation exposure in ESS with balloon catheters Ford D. Albritton, IV, MD, Howard L. Levine, MD, Joseph L. Smith II, MD, Julian Rowe-Jones, FRCS (ORL), Fazlur R. Zahurullah, MD, MBA, Michael Armstrong, MD, Don Duplan, MD, James A. Gershow, MD, Donald A. Leopold, MD, and Frederick A. Kuhn, MD, Dallas, TX; Cleveland, OH; Exton, PA; Surrey, UK; Rockford, IL; Richmond, VA; Port Arthur, TX; Gainesville, FL; Omaha, NE; and Savannah, GA Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article. ABSTRACT OBJECTIVE: Less invasive instruments such as balloon catheters are available for sino-ostial dilation during endoscopic sinus surgery (ESS). Currently, balloon catheter position is confirmed under fluoroscopic visualization. Radiation exposure has been an area of concern. This study was initiated to determine surgeon radiation exposure when fluoroscopy is used during ESS with balloon catheters. STUDY DESIGN: A multi-center, prospective evaluation of surgeon radiation exposure was conducted. SUBJECTS AND METHODS: For three months, 14 sinus surgeons wore dosimeters to record radiation exposure while using C-arm fluoroscopy during balloon catheter-aided sinus surgery. One dosimeter was placed at collar level (chest), outside the lead apron and another dosimeter was placed on a finger (extremity). These dosimeters were sent for readings. Deep, eye, and shallow radiation dose for each surgeon was calculated. RESULTS: Thirteen chest badges recorded annualized averages of 191.08, 193.54, and 187.69 mrems for deep, eye, and shallow exposure respectively. Eleven ring badges recorded 584.00 mrems. CONCLUSIONS: A recent publication reported low levels of surgeon radiation exposure during ESS with balloon catheters. This study validates radiation exposure among experienced surgeons is well below the annual occupational radiation exposure limit of 50,000 mrem. With vigilant technique and education, fluoroscopy reliance can be minimized. © 2009 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved.

T

he addition of balloon sinus dilation catheters to the sinus surgeons’ armamentaria has allowed a natural progression toward surgical conservation while successfully addressing disease in functional endoscopic sinus surgery (FESS). In theory, by creating post-treatment sinus cavities closer to the natural anatomy with greater tissue preservation, we

allow the subunits of the sinonasal tract to work with better synergy. Safe and effective performance of FESS with balloon sino-ostial dilation (FESS-BSD) requires localization of the guide wire into the targeted sinus transition space. Currently localization measures include fluoroscopy and sinus-trans illumination. Fluoroscopy has been used successfully to confirm correct guide wire placement, balloon catheter placement, and adequate sinus ostial dilation at time of balloon inflation. Radiation doses during FESS-BSD have been shown to lie well within safe parameters in previous studies.1-3 Evolution in technique and surgeon experience has allowed modifications in C-arm/fluoroscope use. By reducing radiation time, the absorption of radioactive energy is reduced in the patient, surgeon, and operating room staff, further enhancing safety of the procedure.4 Initial studies have shown the efficacy and safety of FESS-BSD. The purpose of our study is to further demonstrate that the radiation doses to the surgeon in FESS-BSD fall well within safety guidelines. We also examine strategies to use the ALARA (as low as reasonably attainable) principles to decrease radiation exposure in FESS-BSD.

METHODS Fourteen surgeons participated in this prospective study carried out between October 11, 2007 and January 21, 2008. Data were collected on 96 patients already undergoing FESS-BSD for chronic sino-nasal disease failing conservative therapy. All were patients who required sinus surgery for usual indications. Over the three-month period, each participating physician received a numbered dosimeter badge and matching dosimeter ring. Every surgeon kept a standard log. The logs

Received September 13, 2008; revised December 16, 2008; accepted January 13, 2009.

0194-5998/$36.00 © 2009 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved. doi:10.1016/j.otohns.2009.01.013

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Surgeon radiation exposure in ESS with . . .

recorded patient-identifying information, date, and number of sinuses treated. Dosimeters were worn according to protocol with chest badge worn outside the lead apron on the collar, and the ring worn on the dominant hand. Radiation Detection Company, Gilroy, CA (RDC), provided the radiation badges and rings used in the study. RDC is an accredited provider of dosimetry services for the National Voluntary Laboratory Accreditation Program (NVLAP), part of the National Institute of Standards and Technology (NIST). [NVLAP Lab Code 100512-0. http://www.radetco.com/index.html]. Each TLD-XBGN dosimeter badge was a “thermo luminescent” (TLD) badge holder. This type of badge contains both a filter and film. The filters differentiate radiation type (x-ray, beta, gamma, and neutron). As radiation passes through the badge, the filters absorb some of the radiation; the remaining unabsorbed energy passes through the film and darkens it or through the crystals that trap light. The amount of radiation trapped in the chest badge translates into shallow, eye, and deep (body) dose. Eye levels correspond to doses penetrating to tissue depth 0.3 cm. This applies to the exposure seen by the lens of the eye. Shallow and deep dose equivalents alternatively measure the dose equivalents in rem to tissue depths of 0.007 cm and 1 cm, respectively. The extremity dose was calculated from the ring badge. The badges and rings were first returned to Acclarent, Inc, and then sent back to RDC to be read. RDC’s report was generated and sent to Acclarent. The RDC report and data generated from the report have been reviewed and confirmed by the study authors. All measurements were expressed in roentgen equivalent man (rem). An independent biostatistician performed all statistical analysis. As no variation in patient treatment or alteration in standard surgical procedure was made, Institutional Review Board (IRB) approval was not solicited.

RESULTS Fourteen surgeons submitted 13 chest badges and 11 ring badges; 96 surgeries were performed on 302 sinuses (average 3.1 sinuses per case) during the study period. Each chest badge averaged 6.67 patients and 21.42 sinuses. Each ring badge averaged 6.33 patients and 21.67 sinuses. Over the three-month period, chest badge deep exposures ranged from 10 to 260 mrems (mean, 47.77 ⫾ 70.15; median, 18 mrems), eye ranged from 10 to 262 mrems (mean, 48.38 ⫾ 70.76; median, 17 mrems), and shallow ranged from 10 to 240 mrems (mean, 46.92 ⫾ 64.52; median, 19 mrems). Ring badge shallow reading ranged from 10 to 727 (mean, 146.00 ⫾ 214.74; median, 58). By multiplying the three-month period exposure values by 4, we calculated the annualized levels (Table 1). Annualized mean (and median) for deep, eye, shallow, and ring were 191.1 mrems (72 mrems), 193.5 mrems (68

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mrems), 187.7 mrems (76 mrems), and 546.8 mrems (232 mrems), respectively (Table 2). Average surgeon exposure per patient procedure was 9.42 mrems (deep), 9.47 mrems (eye), 9.09 mrems (shallow), and 28.89 mrems (ring). Mean exposure per sinus was 2.89 mrems (deep), 2.89 mrems (eye), 2.80 mrems (shallow), and 11.54 mrems (ring) (Table 1). One of the participating sites had higher readings. Surgeon badge readings from this particular site appear to be an outlier. This is reflected in the higher medians and SD. His facility utilizes an older C-Arm (OEC 7700) that did not provide the option for low-dose, pulse X-ray radiation. He was trained in July 2007 and was able to get his fluoro down to a couple of minutes by the end of the study. Surgeon experience with balloon dilation tools was also assessed as a factor in radiation exposure (Table 4). All study surgeons were placed into three groups based on experience: 1 to 12 months (n ⫽ 5), 12 to 24 months (n ⫽ 6), and ⬎24 months experience (n ⫽ 2). The most experienced surgeons averaged 1.3 mrems for chest badge per sinus and 4.9 mrems for ring badges. Surgeons from the intermediate group (12 to 24 months) averaged 1.9 mrems for the chest and 9.1 for the ring badges. The least experienced surgeons averaged 4.7 mrems for chest and 14.3 mrems for ring badges. The results were not statistically significant due to cohort size.

DISCUSSION Radiation energy is measured in several ways. 1 Gray (Gy) equals 1 joule (J) of radiation energy absorbed by 1 kg of tissue; 1 Gy can be divided into 100 radiation absorbed doses (rads). The biologic effect of the radiation can also be measured by multiplying by a “quality factor.” A Seivert (Sv) is measurement for the biologic equivalent of 1 Gy. For the purposes of our study, mrems are used; 100 mrems equals 1 mSV.5 Radiation is pervasive at extremely low levels throughout the environment. Natural sources include cosmic rays, radon, terrestrial radiation from mineral sources, as well as naturally occurring radionuclides. The average person receives around 0.36 rem (360 mrems)/year from these natural and man-made sources.6,7 Flying frequently and living at higher altitudes increase the exposure rate. Residents of mile-high Denver, Colorado, see double the amount of background radiation as compared to inhabitants of sea level communities. Exposures may also occur from occupational exposures or medical treatments. Allowable doses have been established. Radiation workers in the United States are allowed 5000 mrem/year.8 For those outside of medicine, the allowable cumulative dose is 1 rem/year of age after age 18. Iatrogenic radiation exposure varies widely based on reason for treatment and modality. Diagnostic testing is the

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Table 1 Dosimetry data summary per surgeon Period exposure (mrems)

Surgeon Badge Type

Deep

Eye

Chest Ring

10

10

Chest Ring

16

Chest Ring

Shallow

Annualized exposure (mrems)

Radiaton exposure/ patient (mrems)

Treated

Patient Shallow (n)

Sinuses treated (n) Deep

Deep

Eye

Eye

10 18

40

40

40 72

12

44

0.83

0.3

0.83 1.50

17

15 225

64

68

60 900

9

43

1.78

1.89

97

94

91 10

388

376

364 40

7

29

Chest Ring

10

10

16 *

40

40

64 *

7

24

1.43

Chest Ring

18

17

25 58

72

68

100 232

7

21

Chest Ring

50

50

48 160

200

200

192 640

6

Chest Ring

10

10

10 37

40

40

40 148

Chest Ring

10

10

10 71

40

40

Chest Ring 10 Chest Ring 11 Chest Ring 12 Chest Ring 13 Chest Ring 14 Chest Ring Total Chest Ring

10

10

10 *

40

84

91

88 *

20

20

260

†

Radiaton exposure/ sinus (mrems)

Shallow Deep

Eye

Shallow

0.23

0.23

0.23 0.41

1.67 25.00

0.40

0.40

0.35 5.23

13.00 1.43

3.24

3.24

3.14 0.34

1.43

2.29 *

0.42

0.42

0.67 *

2.57

2.43

3.57 8.29

0.81

0.81

1.19 2.76

13

8.33

8.33

8.00 26.67

3.85

3.85

3.69 12.31

3

5

3.33

3.33

3.33 12.33

2.00

2.00

2.00 7.40

40 284

2

4

5.00

5.00

5.00 35.50

2.50

2.50

2.50 17.75

40

40 *

1

4

10.00 10.00

10.00 *

2.50

2.50

2.50 *

336

364

352 *

16

36

5.25

5.69

5.50 *

2.53

2.53

2.44 *

19 51

80

80

76 204

6

19

3.33

3.33

3.17 8.50

1.05

1.05

1.00 2.68

262

240 727

1040

1048

960 2908

4

15

65.00 65.50

60.00 181.75

17.47 17.47

16.00 48.47

†

† 10

†

†

† 40

1

2

1

2

3 13.9

13.4

4

5

6

7

8

9

† 10.00

† 20.00

26

28

28 103

104

112

112 412

15

43

1.73

1.87

1.87 6.87

0.65

0.65

0.65 9.58

47.77

48.38

46.92 146.00

191.08

193.54

187.69 584.00

96

302

9.42

9.47

9.09 28.89

2.89

2.89

2.80 11.54

*Did not turn in Ring Badge. †Did not turn in Chest Badge.

most common reason for exposure. Some common procedures and their representative doses: one dental x-ray 4-15 mrem (0.04-0.15 mSv); one chest x-ray 10 mrem (0.1 mSv); one mammogram 70 mrem (0.7 mSv). Higher dose procedures include computed tomography (CT) and angiography (Fig 1). CT studies of the sinus are reported to deliver doses to the lens of 1.88 to 64 cGY, whereas 100 cGy may be delivered for a CT of the brain.9-11

Cancer risk from radiation exposure exhibits a linear dose-response. However, even the higher exposure diagnostic studies (such as cardiac catheterization with percutaneous transluminal coronary angioplasty [PTCA]) in the most susceptible (pediatric patients) have not demonstrated overall increased cancer risk in two long-term follow-up studies.12 The National Research Council Committee on the Biologic Effects of Ionizing Radiation (BEIR VII) states

Albritton et al

Surgeon radiation exposure in ESS with . . .

Table 2 Annualized dosage per surgeon (mrems) Chest

Mean SD Minimum Median Maximum

Ring

Deep

Eye

Shallow

Shallow

191.1 280.6 40 72 1040

193.5 283.1 40 68 1048

187.7 258.1 40 76 960

584.0 831.2 40 232 2908

that an effective dose of 1 rem (10 mSV) results in a lifetime risk of developing a radiation-induced cancer at 1 in 1,000. As 4,200 people of 10,000 are expected to develop cancer for other reasons, the relative risk appears small.13 This conclusion does have its detractors who insist damage to solid organs may occur at lower doses.14 Ocular exposure issues are contextually more relevant in FESS-BSD as lower radiation doses are seen with sinus cases. Radiation may cause lens opacification or cataract formation.15 Lens opacity may start around 500 cGy, whereas cataract formation starts with higher doses. Several studies have estimated 2.0 Gy as the low end of the threshold primarily alluding to pediatric subjects.16,17 FESS-BSD doses appear to fall below both neoplasiainducing and ocular-damaging doses. Our mean shallow chest dose was 2.80 mrems/sinus and 9.09 mrems/patient. Extremity doses were 11.54 mrems/sinus and 28.89 mrems/ patient. The C-arms used by the 14 surgeon participants did not have uniform specifications or capabilities. Our data represent a cross-sectional sample of both community and academic practices, highlighting the breadth of the available technology. As many surgeons will not have the most advanced radiographic tools, it is important to verify that safe levels of radiation can still be obtained even with higher emitting devices. The only other study that describes radiation exposure in FESS-BSD by Church et al,3 reports doses of 2.6 mrems/

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sinus and 4.2 mrems/patient in their neck dosimeters while extremity doses were 0.87 mrems/sinus and 2.3 mrems/ patient (Table 3). There is disparity between the two study data sets. If we eliminate continuous fluoroscopy from the data set, our extremity doses more closely shadow theirs. As all of the participants in the Church et al study used C-arms with auto-brightness, maximal collimation, and pulsed x-ray capture, we reviewed our data with and without the continuous C-arm center’s contributions in order to make a better comparison. Based on the large range seen between surgeons, we believe the higher dosing reflects differences in technique, as well as the parameters discussed further. The levels of radiation seen in our study approximate background radiation levels (360 mrems) and fall well within occupational guidelines (5,000 mrems/yr). Tumorigenesis secondary to these annualized dosage ranges is highly unlikely, and cataract formation/lenticular opacification risks are tolerable. Although we cannot demonstrate this statistically, we believe experience plays a role in radiation exposure. Bolger et al1 also suggested that experience led to reduced fluoro time. All of the surgeons in the Church et al study are among the most experienced surgeons with balloon instrumentation. Our cohort was more diverse in terms of surgeon experience and practice location type. As the TLD devices can only determine the cumulative dose for the time period in question, we were unable to observe whether any trends existed over the course of the study with experienced or inexperienced balloon users. Our study did not record fluoro time per case, which is a shortcoming. This might have demonstrated that fluoro times and radiation exposure trended down as surgical experience increased. By placing the surgeons arbitrarily into 3 tiers of experience (⬍12 months, 12 to 24 months, and ⬎24 months), we assessed for a statistical relationship. Superficially, the data appear to support an experience-driven radiation exposure minimalism theory (Table 4). The difference is not statistically significant. The ⬍12 months subset data are likely skewed secondary to the non-pulsed fluoroscopy center. By

Table 3 Surgeon radiation dosage, comparison of collected data (dosage per patient [pt] and per sinus)

Church et al. 2008 Neck (n ⫽ 254 sinuses, 89 patients) Extremity (n ⫽ 182 sinuses, 68 patients) Current Study, (all sites) Chest (n ⫽ 300 sinuses, 95 patients) Extremity (n ⫽ 238 sinuses, 72 patients) Current Study, (excluding non-pulsed c-arm site) Chest (n ⫽ 285 sinuses, 91 patients) Extremity (n ⫽ 223 sinuses, 68 patients)

Dose/pt (mrems)

Dose/sinus (mrems)

Dose/pt (mSv)

Dose/sinus (mSv)

7.200 2.300

2.500 0.870

0.072 0.023

0.025 0.009

7.449 27.189

2.314 6.781

0.074 0.272

0.023 0.068

3.069 11.733

1.173 2.612

0.031 0.117

0.012 0.026

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Table 4 Tiered surgeon experience (in months from training to study entrance) Radiation exposure per sinus (mrems) Mean and median

Tier

Surgeon experience (mean)

n

Mean

Median

Mean

Median

Mean

Median

Mean

Median

⬎24 12-24 1-12

31.5 15.8 4.2

2 6 5

1.3 1.9 4.7

1.3 1.8 8.9

1.3 1.9 4.7

1.3 1.7 8.9

1.3 1.9 4.4

1.3 1.7 8.2

4.9 9.1 14.3

4.9 9.1 25.5

Deep

Eye

removing that center’s data, the means and medians approach the other groups more closely (Table 5). In order to establish experience as a negative influencer on radiation time, we need more dynamic data, rather than cumulative dosimetry. A consensus article from the American College of Cardiology published in 1998 offers guidelines for fluoroscopic procedures.18,19 The essential tenets hold that radiation dose is operator dependent. To minimize radiation exposure, we as surgeons may ensure we use lower frame rate, pulsed fluoroscopy instead of continuous fluoro, with or without magnification. By following this simple change, they estimated radiation dosing could be decreased by as much as 50 percent. In addition, to have the radiation technologist use the highest effective kV setting is preferable to lower the mA. Most modern C-arms automatically optimize these settings. Damage from radiation exposure is much like burn injury in that there are intensity and contact/exposure time relationships. Combined these determine the extent of the injury. Exposure can be influenced through management of the radiologic equipment and use of protective gear (lead aprons, shields, gloves, eye wear).20

Figure 1 Typical radiation exposures from common radiologic procedures.

Shallow

Ring

With the advance of guide wire technology, cues can be nonradiographic, which totally eliminates the need for the C-arm. The Luma wire is a fiber optic guide wire using trans-sinus illumination to confirm correct guide wire position. This enables use of radiation/C-arm only when necessary such as with difficult cases or with surgeons early in their balloon dilation experience. The total elimination of radiation is preferable when safely possible. In order to use the ALARA principles in FESS-BSD, we recommend these measures: ● Use low energy, pulsed settings on C-arm at all times. ● Consult with the radiation technologist to optimimize settings for the C-arm. Radiation exposures may be minimized by raising kV and placing the C-arm at an optimal distance from patient. ● Use the PA projection rather than AP projection to keep the x-ray source as far as possible from the patient and surgeon’s head and neck that may be less protected. ● Use only the lowest amount of fluoro time by relying on endoscopic and tactile cues to navigate into the desired sinus cavity. ● Use “snapshots” to verify correct endoscopic placement, rather than video fluoroscopy as an active navigation tool. ● Avoid using fluoro during dilation of the balloon unless absolutely necessary. ● Position and inflate the balloon without fluoroscopy if the surgeon is confident that the catheter is properly positioned by endoscopy. ● Consider the C-arm a tool for maximum patient safety and not a tool for dynamic intraoperative navigation. By using fluoro only when the physician feels it in the patient’s best interest, we can minimize the exposure times to patient, surgeon, and operating room personnel to the safest levels. Although the radiation levels we have demonstrated fall well under dangerous levels, we can further lower the exposure to environmental background levels or less. Although the future role of radiation in FESS-BSD is uncertain, our data confirm surgeon exposure to be minimal and below government-advised safety thresholds. As the use of sinus-trans illumination guide wires and enhance-

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Surgeon radiation exposure in ESS with . . .

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Table 5 Period and annualized dosage per surgeon (excluding continuous C-arm data) (mrems) Chest Deep Period Mean SD Minimum Median Maximum

Eye

Annualized

30.1 30.5 10 17 97

Ring

120.3 122.2 40 68 388

Shallow

Shallow

Period

Annualized

Period

Annualized

Period

Annualized

30.6 31.1 10 17 94

122.3 124.5 40 68 376

30.8 29.5 10 18 91

123.3 118.0 40 70 364

74.3 70.3 10 55 225

297.2 281.4 40 218 900

ments with image guidance gain wider usage, we would expect radiation usage and consequent exposure to diminish. As long as the C-arm is used, surgeons should modify their technique by using the practice of confirmatory fluoroscopic “snapshots.” This will reduce both patient and surgeon radiation exposure. With this technique, total fluoroscopy times inside of 1 second per sinus are both possible and repeatable in our institution.

CONCLUSION We confirm that radiation levels seen in FESS-BSD expose the surgeon to low levels of radiation similar to the levels of environmental background radiation. These levels are well within the annual recommended maximums for occupational radiation exposure. In addition, we believe radiation dose can be virtually eliminated through ALARA principles and the emergence of new technology.

ACKNOWLEDGEMENTS All statistical analysis performed by an independent biostatistician, Donald Y. Young. ([email protected]). He was independently contracted by Acclarent, Inc, but is not an employee or shareholder in that corporation.

E-mail address: [email protected]. Presented at the Annual Meeting of the American Academy of Otolaryngology–Head and Neck Surgery, September 22, 2008, Chicago, IL.

AUTHOR CONTRIBUTIONS Ford D. Albritton, IV, data collection, data review and analysis, manuscript preparation; Howard L. Levine, data collection, manuscript review/ editing; Joseph L. Smith, II data collection, manuscript review/editing; Julian Rowe-Jones, data collection, manuscript review/editing; Fazlur Zahurullah, data collection, manuscript review/editing; Michael Armstrong, Jr, data collection, manuscript review/editing; Don Duplan, data collection, manuscript review/editing; James A. Gershow, data collection, manuscript review/editing; Donald A. Leopold, data collection, manuscript review/editing: Fred Kuhn, data collection, manuscript review/ editing.

DISCLOSURES Competing interests: Ford D. Albritton IV, consultant and lecturer, Acclarent; Howard L. Levine, Acclarent scientific advisory board, minor stock holder, Carbylan scientific advisory board, ArthoCare scientific advisory board, Medtronic Xomed consultant; Julian Rowe-Jones, consultant, Acclarent; Fazlur Zahurullah, speaker’s bureau, Acclarent, GSK and Sanofi-Aventis; Michael Armstrong, Jr, lecturer for Acclarent; Donald A. Leopold, consultant, MedTronic; Fred Kuhn, Acclarent, Gyrus, G.E. scientific advisory board minor stock holder. Sponsorships: None.

AUTHOR INFORMATION From the Department of Otolaryngology–Head and Neck Surgery (Dr Albritton), Texas Institute for Surgery, Presbyterian Hospital of Dallas; Cleveland Nasal Sinus and Sleep Center (Dr Levine); Ear Nose and Throat Associates of Chester County (Dr Smith); Royal Surrey County Hospital NHS Trust (Dr Rowe-Jones); Department of Otolaryngology–Head and Neck Surgery (Dr Zahurullah), Rockford Health Physicians, Rockford Health System; Virginia Commonwealth University (Dr Armstrong); (Dr Duplan); North Florida Regional Medical Center (Dr Gershow), Gainesville; Department of Otolaryngology–Head and Neck Surgery (Dr Leopold), University of Nebraska Medical Center; and Georgia Nasal and Sinus Institute (Dr Kuhn). Corresponding author: Ford D Albritton IV, MD, Presbyterian Hospital of Dallas, Chairman, Department Otolaryngology–Head and Neck Surgery, Texas Institute for Surgery, 8440 Walnut Hill Ln, Suite 500, Dallas, TX 75231.

REFERENCES 1. Bolger W, Brown C, Church C, et al. Safety and outcomes of balloon catheter sinusotomy: a multi-center 24 week analysis in 115 patients. Otolaryngol Head Neck Surg 2007;137(1):10 –20. 2. Friedman M, Schalch P, Lin HC, et al. Functional endoscopic dilatation of the sinuses: safety, feasibility, patient satisfaction and cost. Am J Rhinol 2008;22(2):204 –9. 3. Church C, Kuhn F, Mikhail J, et al. Patient and surgeon radiation exposure in balloon catheter sinus ostial dilation. Otolaryngol Head Neck Surg 2008;138(2):187–91. 4. Strauss K. Pediatric interventional radiography equipment: Safety considerations. Pediatr Radiol 2006;36(Suppl2):126 –35. 5. Brody A, Frush D, Huda W, et al. Radiation risk to children from computed tomography. Pediatrics 2007;120(3):677– 82.

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6. Kim PK, Zhu X, Houseknech E, et al. Effective radiation dose from radiologic studies in pediatric trauma patients. World J Surg 2005; 29(12):1557– 62. 7. Ritenour E, Geise R. Radiation sources: medicine. health effects of exposure to low-level ionizing radiation. Philadelphia: Institutes of Physics Publishing, 1996;441. 8. Center for Disease Control Website. http://www.bt.cdc.gov/radiation/ measurement.asp. 9. Bassim MK, Ebert CS, Sit RC, et al. Radiation dose to the eyes and parotids during CT of the sinuses. Otolaryngol Head Neck Surg 2005; 133(4):531–3. 10. Cohnen M, Cohnen B, Ewen K, et al. Dosage measurements in spiral CT examinations of the head and neck region. Rofo 1998;168(5): 474 –9. 11. Hopper K, Neuman J, King S, et al. Radioprotection to the eye during CT scanning. AJNR Am J Neuroradiol 2001;22(6):1194 – 8. 12. Klienerman RA. Cancer risks following diagnostic and therapeutic radiation exposure in children. Pediatr Radiol 2006;36Suppl14: 121–5.

13. Lockwood D, Einstein D, Davros W. Diagnostic imaging: Radiation dose and patients’ concerns. Cleve Clin J Med 2006;73(6): 583– 6. 14. Bertell R, Ehrle LH, Schmitz-Feuerhake I. Pediatric CT research elevates public health concerns: low dose radiation issues are highly politicized. Int J Health Serv 2007;37(3):419 –39. 15. Chandra RK. Estimate of radiation dose to the lens in balloon sinuplasty. Otolaryngol Head Neck Surg 2007;137(6):953–5. 16. Ilgit ET, Meric N, Bor D, et al. Lens of the eye: radiation dose in balloon dacryocystoplasty. Radiology 2001;219(2):577– 8. 17. Henk JM, Whitelock RA, Warrington AP, et al. Radiation dose to the lens and cataract formation. Int J Radiat Oncol Biol Phys 1993;25(5):815–20. 18. Campbell RM, Strieper MJ, Frias PA, et al. Quantifying and minimizing radiation exposure during pediatric cardiac catheterization. Pediatr Cardiol 2005;26(1):29 –33. 19. Limacher MC, Douglas PS, Germano G, et al. Radiation safety in the practice of cardiology. J Am Coll Cardiol 1998;31(4):892–913. 20. Aufrichtig R, Xue P. Perpetual comparison of pulsed and continuous fluoroscopy. Med Phys 1994;21:245–56.