Radiotherapy treatment planning system

Radiotherapy treatment planning apparatus for calculating the absorbed dose of radiation irradiated by a radiation source at an observational point within an object to be irradiated, on the basis of the absorbed dose due to the radiation scattered at points other than said observational point and the absorbed dose due to the electron beam generated by the radiation incident to the other points, said radiotherapy treatment planning apparatus, comprising:

• radiation source apparatus for directing radiation to said observational point whereby electron beams are generated by the radiation incident at said observational point and at said points other than said observational point;
• a distribution of contribution output unit for outputting a distribution of contribution representing the distribution, in the object to be irradiated, of the contribution rates of said electron beam to said observational point, a subject setting unit including means for defining a subject region where said other points are present provided that said observational point is present within a range of the electron beam from said other points, and
• an arithmetic unit having means for determining the absorbed dose due to the radiation scattered at the observational point by multiplying the output contribution rates from the distribution of contribution output unit with the electron density at the individual points within the region determined by the subject setting unit and by summing up the multiplied contribution rates.

Radiotherapy treatment planning apparatus for calculating the absorbed dose of radiation irradiated by a radiation source at an elevational point within an object to be irradiated, on the basis of the absorbed dose due to the radiation scattered at points other than said observational point and the absorbed dose due to the electron beam generated by the radiation incident to the other points said radiotherapy treatment planning apparatus comprising:

• radiation source apparatus for directing radiation to said observational point whereby electron beams are generated by the radiation incident at said observational point and at said points other than said observational point;
• a data unit for outputting a distribution of contribution representing the distribution, in the object to be irradiated, of the contribution rates of said scattered radiation to said observational point, a subject region determining unit including means for determining the region, in the object to be irradiated, having a preset contribution rate or a higher contribution rate among said contribution distribution, and for determining the arithmetic matrix size concerning the region, and
• an arithmetic unit including means for determining the absorbed dose of the observational point due to the scattered radiation by multiplying the contribution rates of the scattered radiation at the individual points in the region determined by the subject region determining unit with the electron densities at said individual points and by summing up the multiplied contribution rates.

Radiotherapy treatment planning apparatus including means for calculating the absorbed dose of radiation irradiated by a radiation source at an observational point within an object to be irradiated, on the basis of the absorbed dose due to the radiation scattered at points other than said observational point and the absorbed dose due to the electron beam generated by the radiation incident to the other points, said radiotherapy treatment planning apparatus comprising:

• radiation source apparatus for directing radiation to said observational point whereby electron beams are generated by the radiation incident at said observational point and at said points other than said observational point;
• a data unit for outputting a distribution of contribution representing the distribution, in the object to be irradiated, of the contribution rates of said generated electron beam to said observational point, a subject region determining unit including means for determining the region, in the object to be irradiated, having a preset contribution rate or a higher contribution rate among said contribution distribution, and for determining the arithmetic matrix size concerning the region, and
• an arithmetic unit including means for determining the absorbed dose of the observational point due to the generated electron beam by multiplying the contribution rates of the generated electron beam at the individual points in the region determined by the subject determining unit with the electron densities at said individual points and by summing up the multiplied contribution rates.