Estimating and reducing dose received by cardiac devices for patients undergoing radiotherapy

Abstract

The objectives of this project are to quantify the dose reduction effect provided by a lead shield for patients with cardiac implantable electronic devices (CIED) during a clinically realistic radiation treatment on phantom and to provide a simple model of dose estimation to predict dose received by CIED in a wide range of situations. The shield used in this project is composed of a lead sheet wrapped in thermoplastic. Dose measurements were made with a plastic scintillation detector (PSD). The phantom was treated with ten different plans. Three of these cases were treated with intensity‐modulated radiation therapy (IMRT) and the others received standard 3D conformal radiation therapy (3D CRT). Lateral dose measurement for photon fields was made to establish a dose prediction model. On average, the use of the lead shield reduced the dose to CIEDs by 19%±13%. Dose reduction was most important for breast cases, with a mean reduction of 31%±15%. In three cases, the total dose reduction was more than 25 cGy over the complete treatment. For the three IMRT cases, the mean dose reduction was 11%±9%. On average, the difference between the TPS prediction and the measurement was 71%, while it was only 14% for the dose prediction model. It was demonstrated that a lead shield can be efficiently used for reducing doses to CIED with a wide range of clinical plans. In patients treated with IMRT modality treatment, the shielding should be used only for those with more than two anterior fields over seven fields. In the case of 3D CRT patients, the shielding should be used for those with a dose on the CIED higher than 50 cGy and with a reduction of dose higher than 10 cGy. The dose prediction model developed in this study can be an easy way to have a better estimation of the out‐of‐field dose than the TPS.PACS number(s): 87.55.N, 87.55.km

The effect of stereotactic body radiotherapy (SBRT) using flattening filter‐free beams on cardiac implantable electronic devices (CIEDs) in clinical situations

“…An analysis for maximum doses received by CIEDs (located outside the beam) for all CTPs confirmed that they are all lower than the historical threshold dose of 2 Gy. As can be seen from As detailed by AAPM TG-203, 17 and other studies, 11,24,39 there is no safe dose threshold below which no CIED damage occurs.…”

Re: Estimating and reducing dose received by cardiac devices for patients undergoing radiotherapy

“…In closing, the interpretation of the data by Bourgouin et al (1) is not well‐substantiated for the reasons presented in this letter, and the use of a thin sheet of lead on the CIED is not necessary since it will not prevent internal scatter dose to reach the device. However, it is best if a 5 mm tissue‐equivalent bolus is used to cover the CIED and in vivo dosimetry is implemented as part of the management policy for that category of patients (8) .…”

“…I read with great interest the manuscript of Bourgouin et al, (1) describing methods to estimate and/or measure out‐of‐field doses to a cardiac implantable electronic device (CIED) for patients that undergo radiotherapy. This is a topic that deserves great attention in today's radiotherapy practice since a great number of cancer patients who will receive radiation have a pacemaker or implantable cardioverter‐defibrillator.…”

“…This is a topic that deserves great attention in today's radiotherapy practice since a great number of cancer patients who will receive radiation have a pacemaker or implantable cardioverter‐defibrillator. For this reason, publications like the one under discussion, (1) might be used as guidance to practicing professionals. The purpose of that manuscript was the evaluation of the dosimetric effect that a sheet of lead shield over a CIED has, based on out‐of‐field dose measurements at the location of the CIED, as a way to reduce the dose to the CIED.…”

Response to Re: Estimating and reducing dose received by cardiac devices for patients undergoing radiotherapy

“…In that regard, Fig. 2 (2) should be seen as a demonstration that our dose estimation model can work in different situations, rather than a recommendation to use lead shielding. In our clinic, lead covered in thermoplastic was used because it is easy to manipulate and position on the patient, but we agree that other materials could be used to the same effect.…”