Charged particle irradiation apparatus
Provided is a charged particle irradiation apparatus that performs scanning with a charged particle beam and irradiates an irradiation target spot by spot. An embodiment of the present invention provides a charged particle irradiation apparatus ( 10 ) including: a first dose monitor ( 54 ) mounted in an irradiation nozzle ( 50 ); an irradiation pattern converting device ( 70 ) that generates irradiation control data used for controlling the charged particle irradiation apparatus ( 10 ) from treatment plan data including information on a dose rate and a dose of a charged particle beam for each spot; and a dose correction factor storage unit ( 72 ) that stores data of a dose correction factor with respect to a dose rate of a charged particle beam. The irradiation pattern converting device ( 70 ) is configured to select one spot in the treatment plan data, for instance.
1. A charged particle irradiation apparatus that performs scanning with a charged particle beam and irradiates an irradiation target spot by spot, the charged particle irradiation apparatus comprising:
a first dose monitor mounted in an irradiation nozzle;
an irradiation pattern converting device that generates irradiation control data used for controlling the charged particle irradiation apparatus from input of treatment plan data including information on a dose rate and a dose of a charged particle beam for each spot, wherein the treatment plan data includes information on energy, a dose rate, and a beam size of a charged particle beam for each spot and a spot position; and
a dose correction factor storage unit that stores data of a dose correction factor R 1 with respect to a combination of energy, a dose rate, and a beam size of a charged particle beam and data of a dose correction factor R 2 with respect to a spot position,
wherein the irradiation pattern converting device is configured to
(i) select one spot in the treatment plan data,
(ii) acquire a corresponding dose correction factor R 1 from the dose correction factor storage unit by using energy, a dose rate, and a beam size of a charged particle beam, which correspond to the selected spot and are included in the treatment plan data, as a key,
(iii) acquire a corresponding dose correction factor R 2 from the dose correction factor storage unit by using a spot position, which corresponds to the selected spot and is included in the treatment plan data, as a key,
(iv) correct a dose value corresponding to the selected spot by multiplying a dose value, which corresponds to the selected spot and is included in the treatment plan data, by the dose correction factors R 1 and R 2 acquired in processes of the (ii) and (iii), respectively, and
(v) perform processes of the (i) to (iv) on all of spots in the treatment plan data, and
(vi) generate irradiation control data for a dose by using corrected dose data for all of spots in the treatment plan data, and
wherein the charged particle irradiation apparatus corrects a difference between an actual dose delivered in an irradiation target and a dose measured by the first dose monitor, wherein the difference is caused by influence of ion recombination in the first dose monitor.
2. The charged particle irradiation apparatus according to claim 1 further comprising:
a second dose monitor inside the irradiation nozzle; and
a dose monitor output correction factor storage unit that stores data of an output correction factor used for correcting output of the second dose monitor with respect to energy of a charged particle beam,
wherein the second dose monitor is arranged in downstream of the first dose monitor, and
wherein a monitor unit measured by the second dose monitor is corrected spot by spot by being multiplied by an output correction factor corresponding to energy of a charged particle beam stored in the dose monitor output-correction factor storage unit.