Product Development of Intensity Modulation for Bolus Electron Conformal Therapy

Project Summary Abstract
Electron beam therapy EBT using MeV beams provides effective radiation treatment for superficial
cancers depthandlt cm As many as of radiotherapy patients in USA annually are eligible for
electron therapy for some portion of their treatment making it the second most used external beam
modality As many as of these electron patients annually could benefit from bolus electron
conformal therapy ECT a technique conforming the dose distribution distal isodose surface to the
targeted cancer volume while protecting surrounding healthy tissue from acute and long term adverse
effects of radiation aligning with the agency mission to improve cancer treatment quality Currently
radiation oncologists are limited in the use of bolus ECT because of dose heterogeneity as great as in
the targeted cancer volume due to multiple Coulomb scattering from the irregular proximal bolus surface
This Phase I application proposes to research and develop electron intensity modulation technology
planning software and delivery device which when integrated with existing bolus ECT technology can
eliminate the dose heterogeneity problem i e deliver a more uniform dose distribution dose spread
to the targeted cancer volume Availability of the proposed product intensity modulated bolus ECT should
not only greatly improve current treatments of superficial cancers using electron radiotherapy bolus ECT or
otherwise but in some cases provide an improved alternative to other radiation modalities e g volumetric
arc therapy or intensity modulated radio therapy by having decreased chance of secondary cancers
equally high chance of cancer control and equally low chance of acute normal tissue complications
The proposed delivery technology is an intensity modulator plate which consists of a matrix of
small diameter cylindrical island blocks imbedded in a low density slab attached to the beam defining
collimating insert The magnitude of the intensity modulation is related to the fraction of beam area covered
by the island blocks in a small overlying region By properly varying the diameter and or separation of these
island blocks electron scatter in air should result in a smoothly varying intensity pattern on the patient
and or bolus that restores the dose uniformity in the cancer target volume when using bolus ECT
Phase I goals will be to demonstrate proof of principle by incorporating intensity modulation into
the existing BolusECT software product including a method for segmenting the intensity pattern into an
appropriate matrix of island blocks validating that the planning software modeling the island blocks
produces expected results for select patient sites and validating delivery of the planned intensity
modulated BolusECT beams by demonstrating agreement between delivered measured and planned
calculated dose distributions in water Project Narrative
Electron beam radiotherapy an effective modality for radiotherapy of superficial depth cm cancers
potential US patients year has the ability to protect distal healthy tissue from acute and long
term adverse effects of radiation however radiation oncologists are often limited in use of its most powerful
delivery technique bolus electron conformal therapy ECT because of excessive dose heterogeneity as
great as in the targeted cancer volume due to scatter from the irregular proximal surface of the bolus
This STTR application proposes to research and develop an intensity modulation technology planning
software and delivery device that can be integrated with existing bolus ECT technology previously shown
to provide a more uniform and equally conformal dose distribution to the targeted cancer volume
Heretofore no such product has been available therefore if developed this should not only greatly improve
current electron radiotherapy but potentially provide an improved alternative to other radiation modalities
by providing decreased chance of secondary cancers equally high chance of cancer control and equally low
chance of acute normal tissue complications