The effect of lead free cap on the doses of ionizing radiation to the head of interventional cardiologists working in haemodynamic room

Objectives: The study aim was to analyse the influence of the lead free cap on doses received by interventional cardiologists. The impact of lead free cap on doses to the head were evaluated in number of studies. As different methods used to assess the attenuation properties of protective cap can lead to ambiguous results, a detailed study was performed.

Material and Methods: The effectiveness of a lead free cap in reducing the doses to the skin was assessed in clinic by performing measurements with thermoluminescent dosimeters attached inside and outside the cap first during individual coronary angiography (CA) or CA/percutaneous transluminal coronary angioplasty (CA/PTCA) procedures and then cumulated during few procedures of the same type. In order to investigate the effect of the cap on reducing the doses to the brain additional measurements were performed with a male Alderson Rando and polymethyl methacrylate (PMMA) phantoms representing the physician and the patient, respectively for different projections. The brain dose per procedure, annual and cumulated during entire working practice were estimated for both cases working with and without the cap.

Results: The dose reduction factor (RF) for the skin (the quotient of doses outside and inside the cap) vary from 1.1 up to 4.0 in clinical conditions; on average 2.3-fold reduction is observed in the most exposed left temple. The RFs determined for the part of the head covered by the cap range from 1.4 to 1.8 while for the brain from 1.0 to 1.1 depending on the projection. The estimated annual brain dose for interventional cardiologist performing yearly 550 CA/PTCA procedures without any protective shields is 7.2 mGy and it is reduced with the lead free cap by an average factor of 1.1.

Conclusions: The study results proved the considerable effectiveness of lead free cap to protect the skin but very limited
to protect the brain.