Room: AAPM ePoster Library
Purpose: To introduce the modular remote afterloader (MRA) approach to the cost-effective distribution of ¹6?Yb, which has a 93 keV average ?-ray energy, to clinics for intensity modulated brachytherapy. The conventional distribution model where an engineer travels onsite to perform ¹6?Yb source changes is a costly proposition for ¹6?Yb distribution since its 32-day half-life requires more than double the source-change frequency of conventional ¹?²Ir. The MRA is proposed to address this challenge.
Methods: An MRA was designed with a removeable briefcase-sized cartridge and a wheel-mounted base that receives the cartridge. The cartridge is easily shippable and contains a guidewire-mounted ¹6?Yb source with an activity of up to 54 Ci. The guidewire and source are loaded in a shielded safe, which contains the guidewire drive components that extend and retract the source. The base contains the electronics and power supplies for controlling the components in the cartridge.
Results: The ¹6?Yb source safe can be built with a quarter-toroid of a wall thickness of 3.34 cm of lead or 2.44 cm of tungsten, and a total mass of 5.65 kg of lead or 3.13 kg of tungsten. The safe would have the same external dose rate as a 56.7 kg lead safe claimed for an existing ¹?²Ir afterloader. For source changes, a cartridge with a fresh ¹6?Yb source would be shipped to the clinic for quick installation and quality assurance by clinical staff. The removed lower-activity cartridge is shipped to the vendor for re-loading and preventive maintenance.
Conclusions: The MRA approach is possible since a cartridge containing both the source safe and mechanical drive components can be made small and light enough for ¹6?Yb. Onsite engineers would not be required for all source changes, dramatically reducing the cost of ¹6?Yb distribution but would still be needed for onsite preventative maintenance and repairs.
Funding Support, Disclosures, and Conflict of Interest: RTF is the founder of pxAlpha, LLC, which is developing rotating shield brachytherapy technology.