| CPC A61N 5/10 (2013.01) [A61N 5/1031 (2013.01); A61N 2005/1088 (2013.01)] | 7 Claims |
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1. A treatment device for treatment with a beam (100) of charged particles of a treatment volume (V), the treatment volume (V) comprising a target volume (Vt) including substantially only tumoral cells (3t) and a flash volume (Vht) including healthy cells (3h) and tumoral cells (et), the treatment device comprising:
a pulsed particles accelerator configured to deliver pulses of charged particles for depositing doses (Dij) into the treatment volume (V) by pencil beam scanning (PBS), spot by spot (Si, Ri) distributed over a single painting layer spanning the whole treatment volume (V), such that the doses are deposited into the spots (Si) enclosed within the flash volume (Vht) at a ultra high dose deposition rate (HDR), wherein HDR is defined as a dose rate, HDR≥1 Gy/s, wherein,
the charged particles are emitted by pulses (Pij), each pulse having a pulse charge (Cij) smaller than or equal to a maximum pulse charge (CM) and a duration of pulse time (tp), and the pulses are separated from one another by an interpulse interval (Δtp), and
the beam of charged particles can scan from a first flash spot to a second flash spot at a maximum scan speed (vs=ds/Δts), wherein ds is a distance between the first and second flash spots, and Δts is a scan time required for scanning from the first to the second flash spot; and
a processor configured to control the pulsed particles accelerator to implement a treatment plan (TP), wherein the treatment plan comprises:
a definition of a mesh of N flash spots (Si) covering an area of a projection parallel to an irradiation axis (X) substantially parallel to the beam (100) of the flash volume (Vht) onto a projection plane (H) normal to the irradiation axis (X);
a definition for each flash spot (Si), of a target charge (Cti) required for depositing a target dose (Dti) into the cells spanned by each flash spot (Si);
a definition of a theoretical flash charge planning for each flash spot (Si), including a theoretical pulse charge (Cij) of a number (mi) of pulses required for depositing the target dose (Dti) into the cells spanned by each flash spot (Si), wherein the target charge (Cti) is equal to a sum of the number (mi) of theoretical pulse charges (Cij) irradiating a flash spot (i.e., Cti=Σj=1miCij), or wherein the target dose (Dti) is equal to a sum of the number (mi) of pulse doses (Dij) deposited into the cells spanned by the flash spot by each pulse charge (Cij) (i.e., Di=Σj=1mi Dij); and
a definition of a flash scanning sequence of the N flash spots, including a sequence of flash spots (Si) on which the corresponding number (mi) of pulse doses (Dij) are to be deposited into the cells spanned by each flash spot, wherein the flash scanning sequence comprises:
a definition of a number (k) of sets, each set comprising a number n of flash spots (Si), wherein 1<n<N; and
a definition for each set of n combined flash spots, of a flash scanning subsequence of the n combined flash spots, such that the distance (ds) between every first and second consecutive flash spots ((Si, S(i+1)) and (Sn, S1)) of the set is always lower than or equal to a maximum distance (dM) defined as a product of the scan speed (vs) and a dead time (td) (i.e., d≤dM=vs×td), wherein the dead time (td) is a time between the end of a pulse and a beginning of a next pulse (i.e., td=Δtp−tp), and
wherein the processor is configured for controlling the pulsed particles accelerator to:
(a) point the beam at a first flash spot (S1), i.e, i=1, and deliver a first pulse charge (C11), i.e., with j=1, to deposit a corresponding first pulse dose (D11) into the cells spanned by a first flash spot (S1) of a first flash scanning subsequence of a first set of n combined flash spots;
(b) move the beam to a second flash spot (S2) of the flash scanning subsequence, i.e, i=2, and deliver a first pulse charge (C21) to deposit a first pulse dose (D21) into the cells spanned by the second flash spot (S2) during an estimated time required for measuring during a treatment session an actual first pulse charge (C11) actually delivered at the first flash spot (S1) and compute an adjusted theoretical second pulse charge (C12) to be next delivered at the first flash spot (Si) to align with the theoretical flash charge planning;
(c) if i<n, move the beam to an ith flash spot (Si) in the flash scanning subsequence, deliver a first pulse charge (Ci1) into the cells spanned by the ith flash spot (Si) during an estimated time required for measuring during a treatment session an actual previous pulse charge (C(i−1)1) actually delivered at a previous flash spot (S(i−1)) and compute an adjusted theoretical second pulse charge (C(i−1)2) to be next delivered at the previous flash spot (S(i−1)) to align with the theoretical flash charge planning;
(d) repeat the previous step (n−3) times until i=n;
(e) return the beam to the first flash spot (S1) of the flash scanning subsequence, and deposit the adjusted theoretical second pulse charge (C12) thus computed at the first flash spot (S1), during an estimated time required for measuring during a treatment session an actual first pulse charge (Cn1) delivered at the nth flash spot (Sn) and computing an adjusted theoretical second pulse charge (Cn2) to be next delivered at the nth flash spot (Sn) to align with the theoretical flash charge planning;
(f) repeat (b) to (e) until j=(mi−1) and repeat (b) to (d) for j=mi, at least until the target charge (Cti) has been delivered to each flash spot (S1, Sn) of the first set of n combined flash spots;
(g) move the beam to a first flash spot according to a second flash scanning subsequence of a second set of n combined flash spots and repeat (a) to (f) for the n combined flash spots of the second set of n combined flash spots; and
(h) repeat a last step to the flash scanning subsequences of the remaining (k−2) sets of n combined flash spots until the corresponding target charges (Cti) is delivered at HDR to the n combined flash spots of all k sets of the mesh.
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