Hadron cancer therapy complex using nonscaling fixed field alternating gradient accelerator and gantry design

Nonscaling fixed field alternating gradient (FFAG) rings for cancer hadron therapy offer reduced physical aperture and large dynamic aperture as compared to scaling FFAGs. The variation of tune with energy implies the crossing of resonances during acceleration. Our design avoids intrinsic resonances, although imperfection resonances must be crossed. We consider a system of three nonscaling FFAG rings for cancer therapy with 250 MeV protons and $400\mathrm{MeV}/u$ carbon ions. Hadrons are accelerated in a common radio frequency quadrupole and linear accelerator, and injected into the FFAG rings at $v/c=0.1294$. ${\mathrm{H}}^{+}/{\mathrm{C}}^{6+}$ ions are accelerated in the two smaller/larger rings to 31 and $250\mathrm{MeV}/68.8$ and $400\mathrm{MeV}/u$ kinetic energy, respectively. The lattices consist of doublet cells with a straight section for rf cavities. The gantry with triplet cells accepts the whole required momentum range at fixed field. This unique design uses either high-temperature superconductors or superconducting magnets reducing gantry magnet size and weight. Elements with a variable field at the beginning and at the end set the extracted beam at the correct position for a range of energies.

Figure 1

Schematic layout of the rings.

Figure 2

Schematic layout and orbit functions in a cell of ring 1 at the reference momentum $p_{\mathrm{ref}}=187.2\mathrm{MeV}/c$. The left (middle) rectangle is the F (D) magnet. The object at the right is the rf cavity.

Figure 3

Schematic layout and orbit functions in a cell of ring 2 at the proton reference momentum $p_{\mathrm{ref}}=486.1\mathrm{MeV}/c$ and at the carbon ion reference momentum $p_{\mathrm{ref}}=2.917\mathrm{GeV}/c$. The left (middle) rectangle is the F (D) magnet. The object at the right is the rf cavity.

Figure 4

Schematic layout and orbit functions in a cell of ring 3 at the reference momentum $p_{\mathrm{ref}}=7.896\mathrm{GeV}/c$. The left (middle) rectangle is the F (D) magnet. The object at the right is the rf cavity.

Figure 5

Horizontal cell tune ${\nu }_x$ and vertical cell tune ${\nu }_y$ in a cell of ring 1 as functions of the relative momentum error $dp/p$ from the reference momentum $p_{\mathrm{ref}}=187.2\mathrm{MeV}/c$.

Figure 6

Horizontal cell tune ${\nu }_x$ and vertical cell tune ${\nu }_y$ in a cell of ring 2 as functions of the relative momentum error $dp/p$ from the proton reference momentum $p_{\mathrm{ref}}=486.1\mathrm{MeV}/c$ and from the carbon ion reference momentum $p_{\mathrm{ref}}=2.917\mathrm{GeV}/c$.

Figure 7

Horizontal cell tune ${\nu }_x$ and vertical cell tune ${\nu }_y$ in a cell of ring 3 as functions of the relative momentum error $dp/p$ from the reference momentum $p_{\mathrm{ref}}=7.896\mathrm{GeV}/c$.

Figure 8

Maxima of horizontal $\beta$-function ${\beta }_x$ and vertical $\beta$-function ${\beta }_y$ in a cell of ring 1 as functions of the relative momentum error $dp/p$ from the reference momentum $p_{\mathrm{ref}}=187.2\mathrm{MeV}/c$.

Figure 9

Maxima of horizontal $\beta$-function ${\beta }_x$ and vertical $\beta$-function ${\beta }_y$ in a cell of ring 2 as functions of the relative momentum error $dp/p$ from the proton reference momentum $p_{\mathrm{ref}}=486.1\mathrm{MeV}/c$ and from the carbon ion reference momentum $p_{\mathrm{ref}}=2.917\mathrm{GeV}/c$.

Figure 10

Maxima of horizontal $\beta$-function ${\beta }_x$ and vertical $\beta$-function ${\beta }_y$ in a cell of ring 3 as functions of the relative momentum error $dp/p$ from the reference momentum $p_{\mathrm{ref}}=7.896\mathrm{GeV}/c$.

Figure 11

Horizontal orbit offset $X$ in m along a cell of ring 1 for a range of momentum deviation $-0.35\le \delta p/p\le +0.35$.

Figure 12

Horizontal orbit offset $X$ in m along a cell of ring 2 for a range of momentum deviation $-0.5\le \delta p/p\le +0.5$.

Figure 13

Horizontal orbit offset $X$ in m along a cell of ring 3 for a range of momentum deviation $-0.45\le \delta p/p\le +0.45$.

Figure 14

Maximum negative $\min A_x$ and maximum positive $\max A_x$ values of the horizontal aperture and vertical half aperture $A_y$ in mm for a cell of ring 1 for $-0.35\le \delta p/p\le +0.35$.

Figure 15

Maximum negative $\min A_x$ and maximum positive $\max A_x$ values of the horizontal aperture and vertical half aperture $A_y$ in mm for a cell of ring 2 for $-0.5\le \delta p/p\le +0.5$.

Figure 16

Maximum negative $\min A_x$ and maximum positive $\max A_x$ values of the horizontal aperture and vertical half aperture $A_y$ in mm for a cell of ring 3 for $-0.45\le \delta p/p\le +0.45$.

Figure 17

Schematic layout of the gantry.

Figure 18

Horizontal dispersion $D_x$ in the gantry.