Is It Safe For Patients With Implanted
Cardiac Devices To Undergo Proton Beam
Therapy?
Rohan Samson, MD, Junaid A. Ahmed, MD, Alice Schroeder,
RN, Cynthia Gist, ACNP, Ali Nasur, MD, Naseer Nasser, MD,
Robert Kim, MD, David Nabert, MD and Steve Hsu, MD.
University of Florida, Jacksonville, FL
Disclosures
• Nothing to Disclose
Background
•
Proton therapy is a type of particle therapy which uses a beam of protons to
irradiate diseased tissue, most often in the treatment of cancer.
•
A cyclotron strips hydrogen atoms, accelerates and directs the resulting protons
towards tumors.
•
As protons slow in tissue they deliver the majority of their energy as ionizing
radiation.
•
This process may also produce scatter radiation that impacts cardiac devices.
The Cyclotron
•
Through electrolysis, protons are taken from water and injected into the cyclotron (cylindrical
structure at center) which accelerates protons to nearly the speed of light. The protons are
guided through the beam line at right.
The Beam Line
The protons travel through the beam line, guided by electromagnets, into one of four treatment
rooms.
The Gantry
Proton therapy is delivered while you lie on the treatment table. A gantry rotates to deliver
therapy precisely to the tumor site.
Bragg Peak
• Described by William
Bragg over 100 years
ago
• Depth is dependent on
the energy of the proton
beam
• This energy can be
controlled very precisely
Diseases Treated by Proton Therapy
•
•
•
•
•
•
•
Urological cancers, especially prostate cancer
Lung cancer
Head and neck cancer
Pediatric malignancies
Bone and soft tissue sarcomas
Cancer of the eye and other disorders such as macular degeneration
Brain cancer and cancer of the central nervous system
Proton Beam Statistics
•
As of 2008, 55,000 patients have been treated with proton therapy worldwide
•
In the United States, there are five facilities offering this treatment
•
Locations where PBT is being offered in the US:
The Harvard Cyclotron laboratory at Massachusetts General Hospital
The Proton Treatment Center at Loma Linda University Medical Center (LLUMC)
M.D. Anderson Proton Therapy Center in Houston
University of Pennsylvania's proton facility in Philadelphia
University of Florida's Proton Therapy Institute in Jacksonville
Effect of Proton Beam on cardiac
devices?
• Current implanted cardiac devices are prone to
electromagnetic interference (EMI).
• There is limited literature in the interaction between cardiac
devices and proton beam therapy.
AIM of our study
• To study the Effects of Proton Beam Therapy
on Appropriate Functioning of Implantable
Cardiac Pacemakers and Defibrillators
Methods
•
Prospective study
•
Evaluated patients with Pacemakers, Implantable Cardioverter Defibrillators (ICD)
undergoing proton beam therapy at our Proton Therapy Institute from 2006
through 2010.
•
Device interrogation done at : Baseline (prior to starting therapy)
Immediately post initial therapy
Weekly during the entire treatment duration
•
Inferential statistics in the form of univariate tests (T-tests, Chi square) were
utilized to compare the group with device resets to the group without device
resets on the characteristics collected.
Results
Demographics and Clinical Characteristics
Results
Percentage of pts with
ICDs vs Pacemakers
ICD = 12 pts
PM = 19 pts
Site of Proton beam Therapy
Prostate = 27 pts
Chest = 2 pts
Head/Neck=2 pts
Results
Type of ICD implanted:
Single Chamber ICD = 1 pt
Dual Chamber ICD = 8 pts
BiV-ICD = 3 pts
Device Manufacturers:
Medtronic = 18 pts
St Jude = 5 pts
BSC = 7 pts
ELA = 1 pt
Results – Device Reprogramming
Analysis of Device Reprogramming
Results
• All resets occurred in ICDs, not Pacemakers: Statistically Significant
(p=0.007)
• There was an increased incidence of resets in patients with higher number
of leads: Statistically Significant (p=0.013)
• No statistically significant differences were noted between patients with
device resets and those without device resets when comparing other
variables:
Site of Therapy
Radiation Dose
Conclusions
•
All resets occurred in ICDs, none in Pacemakers
•
Higher incidence of resets in patients with more number of leads.
•
Device resets observed predominantly in Medtronic devices may be a biased observation due
to the large number of Medtronic devices implanted in study population (58% overall).
•
Despite small numbers of patients, we are the first to report observations or significant
findings of any kind involving device resets in patients receiving Proton beam Therapy.
•
As this category of patients grows over time, it will become important to understand the
interactions of Proton Beam Therapy and Cardiac Devices, especially since patients are
dependent on the appropriate functioning of their devices, especially ICDs.
Thank you !
Questions ?