Letter
Letters
September 19, 2019

Peak Skin Dose Estimation in Fluoroscopically Guided Interventions: Is It Necessary?

I read with interest the recent installment of Hallway Conversations in Physics by Ball et al. [1] on the topic of peak skin dose. The authors concisely summarized sound physical principles regarding the estimation of peak skin dose (PSD) in interventional radiology procedures. Dose estimates are based on a conversion of air kerma into absorbed doses or on fluoroscopy times. As is typical in many interventional practices, reports of interventional procedures at my institution include both a dose estimate in milligrays and fluoroscopy time.
PSD calculation is a complex task, and some of the required measurements might not be readily available [2]. PSD estimations are a gross approximation of the actual skin doses patients receive during fluoroscopically guided procedures. Some of the necessary inputs for dose estimation are not precise, and dose calculations end up assuming averages as real values or disregarding geometric variations and other factors that are not taken into account. International minimum requirements for the reporting of kerma area product and cumulative dose at the reference point allow an accuracy of ± 35% [3], which seems rather inaccurate. One solution to the issue of variability in the estimation of skin doses has been to classify patients in bands of doses that may predict skin changes [4]. Even with overlapping in the dose bands of 0–2 Gy, 2–5 Gy, 5–10 Gy, 10–15 Gy, and > 15 Gy, if patients are flagged after a certain dose threshold, clinical follow-up can be warranted. Patients' family or care-givers can be educated about skin changes to look for at specific anatomic sites and at established times after a procedure. After a 5- to 10-Gy exposure band, a timely qualified clinical inspection of the patient by the radiologist involved in the procedure could be mandated [4]. Such flagging and screening should be accompanied by education strategies for everyone on the interventional radiology team and clinical personnel who could be involved in patient care. Lack of awareness can lead to overlooked or misinterpreted injuries. In one patient at my institution who had a transjugular intrahepatic portosystemic shunt (TIPS) and was within the 5- to 10-Gy estimated exposure band, rectangular skin pigmentation that was first seen in an outpatient setting was initially misdiagnosed as having been caused by a malpositioned electrocautery plate. Lack of awareness of radiation effects on the skin and not knowing that electrocauteries are not used in a TIPS procedure delayed diagnosis. Flagging patients according to estimated doses may lead to policies for prompt consultations with a specialized skin wound clinic to begin early treatment and follow-up.
Ball et al. [1] are to be congratulated for approaching this issue with knowledgeable basic science. However, because dose estimations include wide variability, it seems to me that unless more precise calculations can be achieved, estimates of PSD can be impractical and unnecessary. Borrowing from one of the most basic concepts in radiation dose usage, I believe dose estimations should be as practical as reasonably achievable (APARA?).

Footnote

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References

1.
Ball N, Dharmadhikari S, Nye JA. What is peak skin dose? AJR 2019; 212:[web]W107–W108
2.
Jones AK, Pasciak AS. Calculating the peak skin dose resulting from fluoroscopically-guided interventions. Part II. Case studies. J Appl Clin Med Phys 2012; 13:3693
3.
Jones AK, Pasciak AS. Calculating the peak skin dose resulting from fluoroscopically guided interventions. Part I. Methods. J Appl Clin Med Phys 2011; 12:3670
4.
Balter S, Hopewell JW, Miller DL, Wagner LK, Zelefsky MJ. Fluoroscopically guided interventional procedures: a review of radiation effects on patients' skin and hair. Radiology 2010; 254:326–341

Information & Authors

Information

Published In

American Journal of Roentgenology
Pages: W185
PubMed: 31536423

Authors

Affiliations

Anibal J. Morillo
Hospital Universitario de la Fundación, Santa Fe de Bogotá, Bogotá, Colombia
[email protected]

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