Method for efficient daily constancy check or calibration of proton therapy system
View Patent ↗Systems and methods are provided for efficiently performing daily maintenance or quality assurance on proton therapy systems. Specifically, a system is provided which includes a solid-state phantom, a plurality of ionization chambers disposed within the solid-state phantom, and a measuring device coupled to the plurality of ionization chambers and operable to perform radiation measurements of proton beams received within the plurality of ionization chambers. Measurements of proton beams received in the ionization chambers may be used to derive the dose at the ionization chambers and be subsequently compared to pre-generated target data (e.g., data corresponding to proper treatment according to a radiation therapy treatment plan). If the data obtained through the maintenance procedure does not conform to the target data, the proton beam generator may be further calibrated.
1. A method to calibrate a proton spot scanning beam delivery system, the method comprising:
receiving, in a plurality of ionization chambers disposed in a solid-state phantom, a portion of a proton beam emanating from a radiation treatment head and traversing at least a portion of plurality of ionization chambers, the proton beam being directed at the plurality of ionization chambers according to a radiation plan;
detecting, via at least one ionization chamber of the plurality of ionization chambers, a plurality of monitoring units generated in response to charged air particles produced from a passage of the proton beam through the at least one ionization chamber;
measuring a radiation field generated from passage of the proton beam through the portion of the plurality of ionization chambers;
calculating a radiation dose corresponding to the measured radiation field based on a dose absorbed by the plurality of ionization chambers and the number of monitoring units generated from the passage of the proton beam;
comparing the measured radiation field to the set of pre-defined proton beam data, the set of pre-defined proton beam data comprising a target radiation dose; and
calibrating the proton spot scanning beam delivery system to generate a proton beam based on the target radiation dose.
2. The method according to claim 1 , wherein the radiation field comprises at least one of:
a two-dimensional radiation field; and
a homogeneous radiation field.
3. The method according to claim 1 , wherein the radiation field is a mono-energetic radiation field.
4. The method according to claim 1 wherein measuring the radiation field to determine an absorbed dose comprises measuring an absorbed dose per number of monitor units from receiving the proton beam.
5. The method according to claim 1 , wherein the ionization chamber is a thimble ionization chamber.
6. The method according to claim 1 , wherein the ionization chamber is disposed within the solid-state phantom at a shallow depth.
7. The method according to claim 1 , wherein the ionization chamber is disposed within a liquid phantom at a shallow depth.
8. The method according to claim 1 , wherein the proton beam comprises a pencil beam.
9. The method according to claim 1 , wherein the set of pre-defined proton beam data comprises at least one data type from the group comprised of: number of target spots, spot distance, and monitor units per spot.
10. The method according to claim 1 , wherein the plurality of ionization chambers are comprised in a matrix configuration in the solid-state phantom.
11. The method according to claim 1 , further comprising at least one of:
measuring the plurality of monitoring units corresponding to the plurality of ionized air particles produced from the passage of the proton beam through the at least one ionization chamber; and
recording the monitoring units corresponding to the plurality of ionized air particles produced from the passage of the proton beam through the at least one ionization chamber.
12. The method according to claim 11 , further comprising calculating a dose received in the plurality of ionization chambers by determining the ratio of a dose of the proton beam with a number corresponding to the plurality of monitoring units.
13. The method according to claim 1 , wherein a last ionization chamber of the plurality of ionization chambers is positioned to specifically correspond to a distal falloff of the Bragg Peak for the proton beam according to a radiation therapy plan.