Transcript Document

Bragg Peak
By: Megan Whitley
Bragg Peak
 Bragg Peak is the characteristic exhibited by protons
that makes them SO appealing for cancer treatment.
 Due to stopping power, the pristine explosion of energy
at the end of the protons path, and the succinct dose fall
off that occurs after the peak, the integral dose
delivered by protons is half of that of photons.1
Explanation of the plan
comparison on the next slide
 The previous slide held a comparison of two plans,
created for the same patient; the plan on the left was
created using protons and the plan on the right was
created using photons.
 The comparison allows visualization of the dose
delivered outside the tumor, from both entrance and exit
dose, in the photon plan.
 With the proton plan, you can see that although there is
entrance dose, it is not in the dangerous or “hot” range,
and that there is very little exit dose on the distal
portion of the tumor.
Proton Therapy vs Photon Therapy
Explanation of Slide 6
 The next slide demonstrates not only the wasted dose
delivered by the photon beam before and after the
tumor, but it graphically represents Spread Out Bragg
Peak (SOBP).
 By clicking the mouse, the graph will build on itself,
portraying both the differences in photon and proton
pathways, and the building of the flat SOBP.
 This shows how radiation oncology uses the proton to
treat cancer.
The Physics of Protons
Depth Dose Curves for Different Treatment Types
High Energy X-Rays
Spread Out Bragg Peak (SOBP)
Relative Dose
100
8
0
6
0
4
0
200 MeV
Protons
2
0
Tumor
Healthy Tissue
Healthy Tissue
0
0
5
1
0 Depth
1
in5Tissue
20
(cm)
25
3
0
Thank you for you time!
 I hope that these illustrations were beneficial in
understanding Bragg Peak and its use in cancer
treatment.
References
 1. Khan FM, Gerbi B. Treatment Planning in Radiation
Oncology. 3rd ed. Philadelphia, PA: Lippincott Williams &
Wilkins; 2012: 394.