A therapeutic apparatus (500, 600) comprising: - a radiotherapy apparatus for treating a target zone (318, 536) of a subject (316, 526), wherein the radiotherapy apparatus comprises a radiotherapy source (300, 302, 304, 504) for directing electromagnetic radiation (310, 312, 314, 508) into the target zone; - a magnetic resonance imaging system (510, 532, 544, 602) for acquiring magnetic resonance imaging data from an imaging zone, wherein the target zone is within the imaging zone, wherein the magnetic resonance imaging system comprises a magnet for generating a magnetic field within the imaging zone, wherein the radiotherapy apparatus is adapted for rotating the radiotherapy source at least partially around the magnet, wherein the magnetic resonance imaging system does not comprise a radio frequency volume body coil, and further comprises at least two transmit-and-receive channels (528, 530) and a radio-frequency transceiver adapted for simultaneously acquiring the magnetic resonance data from the at least two transmit-and-receive channels (528, 530); - a subject support configured to move in three spatial directions and also be able to rotate about an axis for each of those directions, to allow for free placement of a subject such that the target zone is treated optimally; - a processor; - a memory containing machine executable instructions (636, 638, 640, 642, 644) for execution by the processor, wherein execution of the instructions causes the processor to: - perform (100, 200) a pre-scan calibration of the at least two transmit-and-receive channels using the magnetic resonance imaging system; - acquire (102, 202) the magnetic resonance data in accordance with the pre-scan calibration using the at least two transmit-and-receive channels; - reconstruct (104, 204) a magnetic resonance image from the magnetic resonance data; - register (106, 206) a location of the target zone in the magnetic resonance image; and - generate (108, 208) radiotherapy control signals in accordance with the location of the target zone, wherein the radiotherapy control signals cause the radiotherapy source to irradiate the target zone. - a radiotherapy apparatus for treating a target zone (318, 536) of a subject (316, 526), wherein the radiotherapy apparatus comprises a radiotherapy source (300, 302, 304, 504) for directing electromagnetic radiation (310, 312, 314, 508) into the target zone; - a magnetic resonance imaging system (510, 532, 544, 602) for acquiring magnetic resonance imaging data from an imaging zone, wherein the target zone is within the imaging zone, wherein the magnetic resonance imaging system comprises a magnet for generating a magnetic field within the imaging zone, wherein the radiotherapy apparatus is adapted for rotating the radiotherapy source at least partially around the magnet, wherein the magnetic resonance imaging system does not comprise a radio frequency volume body coil, and further comprises at least two transmit-and-receive channels (528, 530) and a radio-frequency transceiver adapted for simultaneously acquiring the magnetic resonance data from the at least two transmit-and-receive channels (528, 530); - a subject support configured to move in three spatial directions and also be able to rotate about an axis for each of those directions, to allow for free placement of a subject such that the target zone is treated optimally; - a processor; - a memory containing machine executable instructions (636, 638, 640, 642, 644) for execution by the processor, wherein execution of the instructions causes the processor to: - perform (100, 200) a pre-scan calibration of the at least two transmit-and-receive channels using the magnetic resonance imaging system; - acquire (102, 202) the magnetic resonance data in accordance with the pre-scan calibration using the at least two transmit-and-receive channels; - reconstruct (104, 204) a magnetic resonance image from the magnetic resonance data; - register (106, 206) a location of the target zone in the magnetic resonance image; and - generate (108, 208) radiotherapy control signals in accordance with the location of the target zone, wherein the radiotherapy control signals cause the radiotherapy source to irradiate the target zone. - perform (100, 200) a pre-scan calibration of the at least two transmit-and-receive channels using the magnetic resonance imaging system; - acquire (102, 202) the magnetic resonance data in accordance with the pre-scan calibration using the at least two transmit-and-receive channels; - reconstruct (104, 204) a magnetic resonance image from the magnetic resonance data; - register (106, 206) a location of the target zone in the magnetic resonance image; and - generate (108, 208) radiotherapy control signals in accordance with the location of the target zone, wherein the radiotherapy control signals cause the radiotherapy source to irradiate the target zone.