Principles and Practice of Electronic Brachytherapy Jessica Hiatt - - PowerPoint PPT Presentation

Principles and Practice of Electronic Brachytherapy

Jessica Hiatt MS IAEA ICARO, Vienna, Austria April 27, 2009

Brachytherapy:

• Internal radiation therapy that involves

placing radioactive sources inside the patient close to or in the tumor.

Electronic Brachytherapy:

• Internal radiation therapy that involves

placing a miniature x-ray source inside the patient close to or in the tumor.

Xoft Tube (2006)

X-Ray Tube HV Cable

XOFT Axxent Electronic Brachytherapy System:

Controller Source Applicators

• Tube diameter = 2.25 mm
• Requires a cooling catheter

– Assembly diameter = 5.4 mm

• Nominal dose rate:

– 0.6 Gy/min at 3 cm in water

X-ray Source

Comparison of Dose Rate vs. Depth in Water for Various Sources

1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Radius (cm) Dose Rate (cGy/min)

50 kV 50 kV MCNP5 Pd 103 I 125 Ir 192

Graph courtesy of Xoft

Dose rate curve is quite similar to 192Ir over region of interest

Axxent Controller:

Controller Pullback Arm Well Chamber SI Max 4000 Electrometer Touch Screen Display USB Port Barcode Reader

Breast Applicator:

Balloon Inflation Valve Drainage Holes Drainage Port Valves Radiation Source Lumen NO CONTRAST!!

Xoft 50kV MammoSite HDR 192Ir

Dickler et al. Brachytherapy, 2007

Intracavity APBI:

• FDA clearance in May 2008
• Available in four diameters –

20, 25, 30 and 35 mm

• Each set contains four vaginal

cylinders, four source channels and a board & clamp assembly

• Enhanced visibility with CT

and fluoroscopic imaging

Vaginal Applicator Set:

Vaginal Cylinder:

EB IB

EB for Skin:

• Applicator sizes:

– 10, 20, 35, and 50 mm

• Circular
• Stainless steel
• Flattening filter integrated in cone

Scalp treatment with Leipzig applicator

Images provided by Xoft

Advantages of EB:

• Capabilities for IORT
• No isotope handling burden
• Can easily be turned ON/OFF
• Minimal shielding required

AAPM TG-182 Recommendations on Electronic Brachytherapy Quality Management Chair: Bruce Thomadsen

IntraBeam Axxent Clinical Michael Ringor Chris Stacey Gene Cardarelli Mark Rivard Jessica Hiatt Vendor/Vendor Clinical Frank Weigand Randall Holt Ben Smith Calibration/QA Tina Pike Larry DeWerd

EB Conclusions:

• EB has many advantages over isotope-based

brachytherapy

• EB offers the potential to profoundly impact

brachytherapy practice

• EB QA procedures need to be defined
• Clinical studies are necessary to prove EB’s

efficacy