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The Electromagnetic Spectrum

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Electromagnetic waves are categorized according to their wavelengths and frequencies, giving the electromagnetic spectrum. These waves are classified as radio, infrared, ultraviolet, etc. Radio waves refer to electromagnetic radiation with wavelengths ranging from millimeters to kilometers. Radio waves are commonly used for audio communications (i.e., radios) and typically result from an alternating current in the wires of a broadcast antenna. They cover a broad wavelength range and are used...

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When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...

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Related Experiment Video

Updated: Jun 21, 2026

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Published on: June 8, 2018

Energy spectrum control for modulated proton beams.

Wen C Hsi¹, Michael F Moyers, Dmitri Nichiporov

¹Midwest Proton Radiotherapy Institute, Bloomington, Indiana 47408 and University Florida Proton Therapy Institute, Jacksonville, Florida 32206, USA. whsi@floridaproton.org

Medical Physics

|July 21, 2009

Summary

Controlling the proton energy spectrum is crucial for precise proton therapy. Narrowing the energy spread significantly improves dose uniformity and distal edge definition, ensuring effective cancer treatment.

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Area of Science:

Medical Physics
Radiation Oncology
Particle Therapy

Background:

Proton therapy utilizes range-modulated beams for precise dose delivery.
The energy spectrum of protons entering the delivery nozzle impacts dose uniformity and gradient.
Cyclotrons with fixed extraction energy use rangeshifters, which increase energy spread at lower energies.

Purpose of the Study:

To investigate the effects of varying proton energy spreads on dose uniformity and distal edge dose gradient.
To determine acceptable limits for controlling the incident proton energy spectrum.
To evaluate the efficacy of a multilayer Faraday cup (MLFC) for energy spectrum control.

Main Methods:

Calibrated a multilayer Faraday cup (MLFC) using depth dose curves for non-modulated beams.
Measured depth dose curves in water and a multilayer ionization chamber detector for modulated beams with different energy spreads.
Compared results with data from a variable extraction energy synchrotron.

Main Results:

Uncontrolled energy spectra can cause dose nonuniformities up to +/-21% and a 2.5-fold variation in distal penumbra width.
Controlling energy spread within defined limits reduced dose nonuniformity to less than +/-3%.
A wide energy spread at low energies can be advantageous for range modulator device operation.

Conclusions:

Proton beam energy spread control is essential for maintaining dose uniformity within prescription limits.
MLFC can serve as a feedback tool for achieving specified energy spreads.
Optimizing the incident energy spectrum is critical for safe and effective proton therapy.