Patent ID: 8503608
Filing Date: 2013-08-06
Classification: A61N

Abstract:
1. A radiotherapeutic apparatus comprising: a source able to emit a beam of therapeutic radiation along a beam axis, wherein the source is rotatable about a rotation axis that is substantially orthogonal to and intersects with the beam axis thereby to describe an arc around the rotation axis; a multi-leaf collimator (MLC) arranged to collimate the beam to a desired shape; and; a control means able to control a dose/time rate of the source, a rotation speed of the source, and a position of the multi-leaf collimator, i. an MLC leaf movement from a prescribed position at the start of the arc-segment to a prescribed position at the end of the arc-segment, at a maximum leaf speed; ii. rotation of the source from the start to the end of the arc-segment at a maximum source rotation speed; iii. delivery of the dose at a maximum dose rate per time; the apparatus being arranged to select the factor i, ii, or iii which requires longest time, and to control the apparatus so that the selected factor operates at its respective maximum and the remaining factors are operated at a reduced rate selected to match the longest time wherein the total time required for the arc segment for at least one factor relating to a moving geometry item is the greater of (a) a time required to complete the arc segment if the geometry item travelled at a continuous defined upper speed for the geometry item and (b) a time required to allow for adjustment of the speed of the geometry item until it is travelling at the defined upper speed.