Establishing radiation therapy treatment planning effects involving implantable pacemakers and implantable cardioverter‐defibrillators

Michael S Gossman,Jeffrey D Wilkinson,Alison R Graves‐Calhoun

doi:10.1120/jacmp.v11i1.3115

Michael S Gossman, Jeffrey D Wilkinson + Show 1 more

Open Access

https://doi.org/10.1120/jacmp.v11i1.3115

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Abstract

Recent improvements to the functionality and stability of implantable pacemakers and cardioverter‐defibrillators involve changes that include efficient battery power consumption and radiation hardened electrical circuits. Manufacturers have also pursued MRI‐compatibility for these devices. While such newer models of pacemakers and cardioverter‐defibrillators are similar in construction to previously marketed devices – even for the recent MRI‐compatible designs currently in clinical trials – there is increased interest now with regard to radiation therapy dose effects when a device is near or directly in the field of radiation. Specifically, the limitation on dose to the device from therapeutic radiation beams is being investigated for a possible elevation in limiting dose above 200 cGy. We present here the first‐ever study that evaluates dosimetric effects from implantable pacemakers and implantable cardioverter‐defibrillators in high energy X‐ray beams from a medical accelerator. Treatment plan simulations were analyzed for four different pacemakers and five different implantable cardioverter‐defibrillators and intercompared with direct measurements from a miniature ionization chamber in water. All defibrillators exhibited the same results and all pacemakers were seen to display the same consequences, within only a a±1.8% deviation for all X‐ray energies studied. Attenuation, backscatter, and lateral scatter were determined to be −13.4%, 2.1% and 1.5% at 6 MV, and −6.1%, 3.1% and 5.1% at 18 MV for the defibrillator group. For the pacemaker group, this research showed results of −15.9%, 2.8% and 2.5% at 6 MV, and −9.4%, 3.4% and 5.7% at 18 MV, respectively. Limited results were discovered from scattering processes through computer modeling. Strong verification from measurements was concluded with respect to simulating attenuation characteristics. For IP and ICD leads, measured dose changes were less than 4%, existing as attenuation processes only, and invariant with regard to X‐ray energy.PACS number: 87.53.Bn, 87.53.Dq, 87.53.Tf, 87.66.Jj

Highlights

Twelve years of further research went into the development of a device capable of correcting both for the onset of arrhythmia and ventricular fibrillation
Researchers struggled to create a device capable of sending multiple electrical impulses and providing different levels of electrical shock when required.[5]. The aim was to determine if it were possible to design a device that could modulate the impulse sent to increase low heart rates to an acceptable rate, deliver a mild shock synchronized to an in appropriately fast heart rate, or deliver a much more powerful shock to a heart in ventricular fibrillation.[6]. The use of computer algorithms and advancing hardware, pioneered by a team led by Michel Mirowski and Morton Mower, resulted in the first ever implantable cardioverter-defibrillator (ICD) in 1969.(7)
When presented with a task to treat patients that have been prescribed an implantable cardioverter-defibrillator or implantable pacemaker, many options exist for radiation oncologists to consider

Summary

Introduction

Twelve years of further research went into the development of a device capable of correcting both for the onset of arrhythmia and ventricular fibrillation. Researchers struggled to create a device capable of sending multiple electrical impulses and providing different levels of electrical shock when required.[5] The aim was to determine if it were possible to design a device that could modulate the impulse sent to increase low heart rates to an acceptable rate (pacing), deliver a mild shock synchronized to an in appropriately fast heart rate (cardioversion), or deliver a much more powerful shock to a heart in ventricular fibrillation (defibrillation).(6) The use of computer algorithms and advancing hardware, pioneered by a team led by Michel Mirowski and Morton Mower, resulted in the first ever implantable cardioverter-defibrillator (ICD) in 1969.(7). When the material being irradiated is not similar to that of a patient – like a metallic pacemaker, for example – the physics of the radiation beam is altered This presents a challenge on multiple levels. Problems are known to have occurred during in vitro testing.[8,9] From these observations, clinicians have been made aware of possible interactions with implanted and external devices. [10] is this an issue during computerized tomography (CT) image acquisition initially, but it is an issue for delivering radiation for the treatment of cancer.[11,12] Figure 1 illustrates the size and location of such devices from a chest X-ray radiograph

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