Patent Description:
During CT scanning, a patient is usually moved by a patient support system (examination table). However, in some special cases, for example, the patient is under surgery or has an open wound, the patient cannot be moved and CT scanning is performed by moving a gantry. This requires a movable gantry undercarriage that can carry and transport the gantry. With this undercarriage, the gantry can be transported outside the scanning room and used in several rooms.

Motion precision is very important for mobile CT and is directly related to image quality of scanning. However, the motion precision of the mobile CT is affected by a variety of factors, including ground flatness and installation precision of a mechanical structure.

<CIT> discloses a medical imaging apparatus and a control method of the same. The medical imaging apparatus including a rotatable gantry in which an X-ray generator configured to generate X-rays and emit the X-rays to an object and an X-ray detector configured to detect the X-rays emitted from the X-ray generator are arranged to face each other, the medical imaging apparatus includes a mover configured to move the medical imaging apparatus, a sensor configured to measure position data according to the movement of the gantry; generate image data based on the detected X-rays, correct the image data based on the measured position data, and generate an X-ray computed tomography (CT) image based on the corrected image data.

<CIT> discloses medical imaging devices, systems, and methods. The medical imaging system may include a movable station and a gantry. The movable station includes a gantry mount rotatably attached to the gantry. The gantry includes an outer C-arm slidably mounted to and operable to slide relative to the gantry mount, an inner C-arm slidably coupled to the outer C-arm and, an imaging signal transmitter and sensor attached to the C-arms. The two C-arms work together to provide a full <NUM> degree rotation of the imaging signal transmitter. The movable station may include a motion control system and an imaging control system. In embodiments, the motion control system includes omnidirectional wheels for precision controlled-movement of the movable station.

<CIT> discloses an imaging system. The imaging system is operable to acquire and/or generate image data at positions relative to a subject. The imaging system includes a drive system configured to move the imaging system.

<CIT> discloses a mobile imaging system for imaging of patients in medical interventions comprising a ring gantry with a plurality of independently rotating rings whereas a first rotating ring positions an X-ray source with collimator and a second rotating ring positions an image detector such that the region of interest (patient) can be positioned off-centered with respect to the ring center.

In view of this, the present invention provides a medical device undercarriage and a medical device system.

According to a first aspect of the present invention, a medical device undercarriage is provided, including a pair of front wheels, a pair of rear wheels, a first position sensitive detector located between the pair of front wheels, a second position sensitive detector located between the pair of rear wheels, and a controller; and the controller calculates a gear ratio of the rear wheels according to a position of the first position sensitive detector and a position of the second position sensitive detector.

In an embodiment, if a position deviation of the first position sensitive detector is Ep(n), the controller calculates Ep(n) according to the following formula: <MAT> where Nis a positive integer, and dt is a sampling interval, Kpp, Kpi, and Kpd are respectively proportional integral differential coefficients of related positions.

In an embodiment, if the position of the first position sensitive detector is P<NUM>, the position of the second position sensitive detector is P<NUM>, and an angle deviation of the second position sensitive detector is Ea(n), the controller calculates Ea(n) according to the following formula: <MAT> where d(P<NUM> - P<NUM>) is a position difference between the first position sensitive detector and the second position sensitive detector.

In an embodiment, if the gear ratio of the rear wheels is GR, the controller calculates GR according to the following formula: <MAT> where Kap, Kai, and Kad are respectively proportional integral differential coefficients of related angles.

In an embodiment, the front wheel includes a mobile encoder, a mobile motor, and a mobile drive, and the rear wheel includes a steering encoder, a steering motor, and a steering drive.

According to a second aspect of the present invention, a medical device system is provided, including a medical device and the medical device undercarriage described above, where the medical device is disposed on the medical device undercarriage, and the controller sends the gear ratio of the rear wheels to the medical device.

For the medical device undercarriage and system of the present invention, no track is required to control motion, and no absolutely flat ground is required. The medical device undercarriage and system can be used on a relatively flat ground, have low costs, and are slightly environment-dependent.

To enable a person of ordinary skill in the art to understand the foregoing and other features and advantages of the present invention more clearly, exemplary embodiments according to the present invention are described in detail below with reference to the accompany drawings. In the accompany drawings:.

In the accompany drawings, reference numerals used are as follows:.

To make the objective, technical solutions, and advantages of the present invention clearer, the present invention is further described in detail below by using embodiments.

<FIG> is a schematic structural diagram of a medical device undercarriage <NUM> according to an embodiment of the present invention. <FIG> is a functional block diagram of the medical device undercarriage <NUM> according to an embodiment of the present invention. Ideally, the medical device undercarriage <NUM> will travel in a Y direction, but in fact it will be offset in an X direction. Motion inertia of a gantry is very large, and a back gap exists in a mobile mechanism, so it is difficult to measure a static error. To reduce impact on scanning and reconstruction, a deviation in the X direction should be within <NUM>.

As shown in <FIG>, the medical device undercarriage <NUM> includes a undercarriage plate <NUM>, a pair of front wheels <NUM>, a pair of rear wheels <NUM>, a first position sensitive detector <NUM> located between the pair of front wheels <NUM>, a second position sensitive detector <NUM> located between the pair of rear wheels <NUM>, and a controller <NUM>. The first position sensitive detector <NUM> and the second position sensitive detector <NUM> emit a laser beam <NUM>.

As shown in <FIG>, the front wheel <NUM> includes a mobile encoder <NUM>, a mobile motor <NUM>, and a mobile drive <NUM>, and the rear wheel <NUM> includes a steering encoder <NUM>, a steering motor <NUM>, and a steering drive <NUM>. The first position sensitive detector <NUM> and the second position sensitive detector <NUM> send their position information to the controller <NUM>. The controller <NUM> calculates a gear ratio of the rear wheels <NUM> according to a position of the first position sensitive detector <NUM> and a position of the second position sensitive detector <NUM>. A medical device <NUM> may be disposed on the medical device undercarriage <NUM>, and the controller <NUM> may send the gear ratio to the medical device <NUM>.

Offsets of the two positions on the undercarriage <NUM> relative to the traveling direction may be obtained from the first position sensitive detector <NUM> and the second position sensitive detector <NUM>. The position of the first position sensitive detector <NUM> is P<NUM>, the position of the second position sensitive detector <NUM> is P<NUM>, the position P<NUM> of the first position sensitive detector <NUM> is a position error, and P<NUM> - P<NUM> is an angle error.

<FIG> is a schematic diagram of a position deviation <NUM> and an angle deviation <NUM> of a medical device undercarriage <NUM> according to an embodiment of the present invention.

First, to reduce the position error of P<NUM>, the position deviation is used as an input to the first proportional integral differential (PID) loop, and a half-position PID algorithm is used herein. Deviation values of a position sensitive detector at N sampling points are recorded as input deviation values, and N may be a value between <NUM> and <NUM>, which can not only increase reliability of deviation correction, but also reduce processor burden.

If a position deviation of the first position sensitive detector <NUM> is Ep(n), the controller <NUM> may calculate Ep(n) according to the following formula: <MAT> where Nis a positive integer, and dt is a sampling interval, Kpp, Kpi, and Kpd are respectively proportional integral differential coefficients of related positions, and may be obtained through test.

Then, the obtained correction deviation is added to adjustment of the angle deviation, so that adjustment of the angle deviation approaches <NUM> and reduces the position deviation.

If an angle deviation of the second position sensitive detector <NUM> is Ea(n), the controller <NUM> may calculate Ea(n) according to the following formula: <MAT> where d(P<NUM> - P<NUM>) is a position difference between the first position sensitive detector <NUM> and the second position sensitive detector <NUM>. In this embodiment, d(P<NUM> - P<NUM>) is in a unit of micron. Therefore, it needs to be divided by <NUM> for unit conversion.

A correction amount obtained after the PID loop is compared with an existing speed difference, and further correction is performed. In addition, to increase motion flexibility and smoothness, a rear wheel swivel angle is added, and a deviation angle of the rear wheel is obtained in real time by using a motion center as an origin according to a differential deviation that needs to be corrected.

If the gear ratio of the rear wheels <NUM> is GR, the controller <NUM> may calculate GR according to the following formula: <MAT> where Kap, Kai, and Kad are respectively proportional integral differential coefficients of related angles, and may be obtained through test.

<FIG> is a schematic diagram of motion of a medical device undercarriage <NUM> according to an embodiment of the present invention. The rear wheel <NUM> is deflected around an origin <NUM>, so that a undercarriage plate <NUM> has path planning <NUM>, thereby returning to the ideal traveling route Y.

A measurement range of a high-precision position sensitive detector (PSD) is +/-<NUM>, and resolution is <NUM>. In this embodiment, a distance between steering wheels (rear wheels) is <NUM>, and a diameter of the steering wheel is <NUM>. If only traveling wheels (front wheels) are controlled synchronously in real time, a deviation of <NUM>-<NUM> will occur when moving by <NUM> at <NUM>/s. With the controller of this embodiment, the deviation is reduced to <NUM>.

The present invention further provides a medical device system, including a medical device <NUM> and the medical device undercarriage <NUM>. The medical device <NUM> is disposed on the medical device undercarriage <NUM>. The controller <NUM> sends the gear ratio of the rear wheels <NUM> to the medical device <NUM>.

Claim 1:
A medical device undercarriage (<NUM>), comprising a pair of front wheels (<NUM>), a pair of rear wheels (<NUM>), a first position sensitive detector (<NUM>) located between the pair of front wheels (<NUM>), a second position sensitive detector (<NUM>) located between the pair of rear wheels (<NUM>), and a controller (<NUM>), wherein
the controller (<NUM>) calculates a gear ratio of the rear wheels (<NUM>) according to a position of the first position sensitive detector (<NUM>) and a position of the second position sensitive detector (<NUM>).