Field
The application relates to a medical apparatus, and more particularly, relates to a medical apparatus for delivering radiotherapy.
Description
Radiotherapy is a method which transmits radioactive rays such as α-rays, β-rays, or γ-rays, generated by radioisotopes, X-rays, electron beams, proton beams or other particles, to diseased tissue (e.g., a cancerous tumor). The rays kill cells of the tissue by causing ionizations within the cells or other cell damage.
A linear accelerator is a particle accelerator commonly used for radiotherapy. A linear accelerator comprises a radiation head in which a radiation source is arranged for radiating a radioactive beam toward diseased tissue. The radiation source may include an accelerating tube, an electron gun, a moving target, a magnetic biasing system, a collimator, and a flattening filter. The radiation head also includes a high-density lead shielding layer to prevent extraneous radioactive rays from harming bystanders during use of the linear accelerator. The above components, and others, contribute to the substantial mass of the radiation head.
Conventional radiotherapy is typically performed in conjunction with a computed tomography (hereinafter, “CT”) imaging apparatus or a magnetic resonance (hereinafter, “MR”) imaging apparatus to determine a specific position of the diseased tissue and to thereby properly position the diseased tissue relative to the emitted rays of the linear accelerator. As is known in the art, a CT imaging apparatus is particularly suited for imaging bone and an MR imaging apparatus is particularly suited for imaging soft tissue.
In one example, a patient is positioned within an imaging apparatus to image the diseased tissue and refine the patient's position, and the patient is then moved to the linear accelerator to radiate the diseased tissue. Since both the linear accelerator and the imaging apparatus occupy a large volume, the patient is moved over a substantial distance therebetween, thereby complicating the procedure and increasing the risk and extent of positioning errors.
FIG. 19 illustrates a prior combined medical apparatus 100. The medical apparatus 100 comprises a radiation therapy assembly 102, an imaging assembly 104, and a couch assembly 106. More particularly, the radiation therapy assembly 102 is a common radiotherapy apparatus, which comprises a gantry 1022 in which a through-hole 1024 extending along a horizontal direction is defined. One end of an arm 1026 is secured to the gantry 1022 and the other end thereof extends outwardly. A radiation head 1028 is fixed to the other end of the arm 1026. The imaging assembly 104 is a common CT imaging apparatus, which comprises a gantry 1042 defining a through-hole 1044 extending along a horizontal direction. An X-ray tube 1046 and a detector 1048 are arranged oppositely on a rotatable mechanism (not shown) surrounding the through-hole 1044. The couch 106 comprises a base 1062 and a patient support 1064 arranged on the base 1062.
In order to image a patient, the patient is placed on the patient support 1064, and the patient support 1064 is moved through the through-holes 1024 and 1044 in order to position the patient between the X-ray tube 1046 and the detector 1048. The X-ray tube 1046 and the detector 1048 are then operated as is known in the art to acquire an image of the patient. To radiate the patient, the patient support 1064 is moved such that the target volume, determined from the acquired image, is positioned in the beam field of the radiation head.
The length spanned by the through-holes 1024 and 1044 or, more particularly, the distance from the isocenter of the radiation therapy assembly 102 to the imaging plane of the imaging assembly 104, is quite long. The resulting movable distance of the patient support 1064 is directly related to the likelihood that deformation of the couch assembly and/or the patient support will introduce errors in imaging and/or radiation delivery. Additionally, as recited above, the large volume occupied by the combined medical apparatus 100, consisting of the radiation therapy assembly 102 and the imaging assembly 104, poses a significant challenge to any institution (e.g., a hospital) employing the apparatus 100.
FIG. 20 illustrates another prior combined medical apparatus 200. The medical apparatus 200 comprises a radiation therapy assembly 202, an imaging assembly 204 and a couch assembly 206. The radiation therapy assembly 202 comprises a gantry 2021 defining a through-hole 2022 extending along the horizontal direction. One end of an arm 2023 is secured to the gantry 2021 and the other end thereof extends outwardly. A radiation head 2024 is fixed on this other end of the arm 2023. The imaging assembly 204 is a CT imaging assembly which comprises a gantry 2041 defining a through-hole 2042 along the horizontal direction. An X-ray tube 2043 and a detector 2044 are oppositely arranged around through-hole 2042 on a rotatable mechanism (not shown). The couch assembly 206 comprises a base 2061 and a rotatable platform 2062 which is coupled to the base 2061 and rotatable about a vertical axis 2063. A patient support 2064 is slidably secured to the platform 2062, and a patient P is shown positioned on the patient support 2064.
In contrast to the combined medical apparatus 100 as shown in FIG. 19, the radiation therapy assembly 202 and the imaging assembly 204 of the medical apparatus 200 are separately arranged, and the couch assembly 206 is arranged between the radiation therapy assembly 202 and the imaging assembly 204. Accordingly, during the transition between an imaging mode and a radiating mode, the movement of the patient support 2064 differs from the movement of the patient support 1064 as shown in FIG. 19, i.e., the patient support 2064 rotates to change between the two modes but the patient support 1064 translates linearly to change modes.
The movable distance of the patient support 2064 is shorter than that of the patient support 1064 in FIG. 19, and thus, the apparatus 200 attempts to address the problem of flexible deformation of the patient support 2064. However, since the apparatus 200 requires sufficient distance between the radiation therapy assembly 202 and the imaging assembly 204 such that the patient support 2064 can be rotated without interference with the radiation therapy assembly 202 and the imaging assembly 204, the space occupied by the medical apparatus 200 is unsuitably large.
Thus, technical solutions are desired in radiotherapy to reduce complications, increase efficiency of resource usage, and decrease positioning error.