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METHOD AND APPARATUS FOR IMPROVING THE VACUUM IN MEDICAL CYCLOTRONS

IP.com Disclosure Number: IPCOM000246207D
Publication Date: 2016-May-17
Document File: 3 page(s) / 12K

Publishing Venue

The IP.com Prior Art Database

Abstract

Techniques for improving the vacuum conditions in negative hydrogen ion medical cyclotrons, including installing getter modules close to the ion source or inside the acceleration chamber are presented. The getter modules absorb or adsorb neutral hydrogen introduced into the ion source. This is preferably done close to the ion source thereby reducing loose hydrogen that reduces the vacuum conditions. This reduces beam particle losses and the heating of parts hit by these lost particles. This heating may further increase the number of lost particles, reduce the vacuum further, and thereby require a higher initial beam current output from the ion source.

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METHOD AND APPARATUS FOR IMPROVING THE VACUUM IN MEDICAL CYCLOTRONS

FIELD OF INVENTION

The invention generally relates to medical cyclotrons, and more particularly to use of getter modules in negative hydrogen ion medical cyclotrons.

ABSTRACT

Techniques for improving the vacuum conditions in negative hydrogen ion medical cyclotrons, including installing getter modules close to the ion source or inside the acceleration chamber are presented. The getter modules absorb or adsorb neutral hydrogen introduced into the ion source. This is preferably done close to the ion source thereby reducing loose hydrogen that reduces the vacuum conditions. This reduces beam particle losses and the heating of parts hit by these lost particles. This heating may further increase the number of lost particles, reduce the vacuum further, and thereby require a higher initial beam current output from the ion source.

BACKGROUND OF THE INVENTION

In a conventional medical cyclotron, particles are lost or separated from the ion beam during the acceleration phase of the beam. This generally causes deterioration of the vacuum in the cyclotron. Further, the lost particles hit internal parts, causing heating thereof. The heated parts, in turn, further release particles from their surface, causing an undesirable cycle in which more heat is generated and more particles are lost, which increasingly deteriorates the vacuum conditions in the cyclotron.

High levels of lost beam require a higher beam current output from the source to reach the required target beam current. However, increasing the beam current output leads to higher levels of lost beam, more heating of internal parts, and consequently further deterioration of the vacuum conditions. In this manner, deploying higher beam current outputs simultaneously deteriorate the vacuum conditions in the cyclotron, putting a ceiling on the effectiveness of increasing the beam current output for desired applications.

Furthermore, high energy particles lost from the ion beam impact the materials inside the accelerator, leading to increased levels of prompt radioactivity, and create long-lived radioactive isotopes in such materials, which is in general undesirable in cyclotrons.

Conventional vacuum pumps are positioned far from the acceleration path and operate by trapping or removing particles that traverse through the acceleration area to reach the vacuum pumps. This process cannot be further enhanced by added pumping capacity outside of the beam path, because losing particles from the ion beam is a stochastic...