CN-122003276-A - Patient positioning for fiducial marker-free radiation therapy

Abstract

Methods and systems for positioning and locating a patient for radiation therapy without fiducial markers. A table setting is obtained that includes parameters of the patient support table. Platform position data is obtained, wherein the patient is positioned on the platform for imaging without fiducial markers, the platform position data comprising 3D coordinates of the platform relative to an imager coordinate system calibrated to a predefined fixed set of initialization coordinates in the treatment room. The target tissue is imaged with the patient on the platform. A treatment plan is generated based on the target tissue imaging. The treatment plan includes a treatment field of treatment angles including a stage positioning parameter. When starting treatment, the patient is placed on the platform without fiducial markers, according to the platform settings. The table is adjusted to position the patient in a home position in the treatment room such that the target tissue is positioned at an isocenter of the treatment room, based on the treatment plan, the table position data, and a coordinate system transformation of the imager coordinate system to the treatment room coordinate system.

Inventors

• Himmson Vinograd

Assignees

• P-Cure有限责任公司

Dates

Publication Date

20260508

Application Date

20240825

Priority Date

20230831

Claims (19)

1. 1. A method for positioning and locating a patient for radiation therapy without fiducial markers, the method comprising the steps of: obtaining a table setting comprising parameters of a patient support table for supporting a patient during radiation therapy; Obtaining platform position data of the support platform, wherein a patient is disposed on the support platform without fiducial markers for imaging, the platform position data comprising 3D coordinates of the support platform relative to an imager coordinate system of an imager calibrated to a predefined and fixed set of initialization coordinates in a treatment room; Imaging a target tissue of a patient on the support platform using the imager, Generating a treatment plan based on imaging of the target tissue, the treatment plan comprising a plurality of treatment shots, each of the treatment shots comprising a treatment angle comprising at least one table positioning parameter of the support table for positioning a patient such that the target tissue is positioned at an isocenter of the treatment room; When the irradiation treatment is started, placing the patient on the support table without fiducial markers according to the table setting, and The support platform is adjusted to position the patient at a positioning position in the treatment room such that the target tissue is positioned at an isocenter of the treatment room, according to the treatment plan, the platform position data, and a coordinate system transformation of the imager coordinate system to a room coordinate system of the treatment room.
2. 2. The method of claim 1, further comprising determining the coordinate system transformation by imaging a dedicated imaging phantom with the imager, the dedicated imaging phantom including a plurality of markers disposed at known locations relative to the chamber coordinate system, identifying a phantom marker in imaging of the imaging phantom, determining a phantom coordinate system in the imager coordinate system based on the locations of the phantom markers, and determining the transformation of the imager coordinate system to the chamber coordinate system based on the phantom coordinate system and the known locations of the phantom marker relative to the chamber coordinate system.
3. 3. The method of claim 1, further comprising verifying the positioning of the patient after moving the support platform to position the patient.
4. 4. The method of claim 3, wherein verifying the positioning of the patient comprises capturing a plurality of orthogonal stereo X-ray images and adjusting the positioning of the patient based on the captured X-ray images.
5. 5. The method of claim 3, wherein verifying the positioning of the patient comprises imaging the patient to generate a therapeutic imaging model, identifying differences between the therapeutic imaging model and a reference imaging model generated from the first imaging, and adjusting the positioning of the patient based on the identified differences.
6. 6. The method of claim 1, wherein the patient support platform is adjustable using a platform adjuster configured to rotate at least one platform surface of the platform about at least one axis of rotation and displace at least one platform surface of the platform along at least one axis of displacement.
7. 7. The method of claim 1, wherein the patient support platform is a chair, and wherein the patient is in a sitting position.
8. 8. The method of claim 1, wherein the radiation therapy comprises proton radiation therapy.
9. 9. The method of claim 1, wherein the step of imaging the target tissue includes sequentially repositioning and redirecting the movable imager relative to the stationary patient to obtain a plurality of images at a plurality of imaging angles.
10. 10. A system for positioning and locating a patient for radiation therapy without fiducial markers, the system comprising: A processor configured to obtain a platform setting comprising parameters of a patient support platform for supporting a patient during radiation therapy, and to obtain platform position data of the support platform, wherein a patient is placed on the support platform without fiducial markers for imaging, the platform position data comprising 3D coordinates of the support platform relative to an imager coordinate system of an imager calibrated to a predefined and fixed set of initialization coordinates in a treatment room, and An imager configured to image a target tissue of a patient on the support platform, Wherein the processor is further configured to generate a treatment plan based on imaging of the target tissue, the treatment plan comprising a plurality of treatment fields, each of the treatment fields comprising a treatment angle comprising at least one platform positioning parameter of the support platform for positioning the patient such that the target tissue is positioned at an isocenter of the treatment room, and Wherein when the radiation therapy is started, the patient is placed on the support platform without fiducial markers according to the platform settings, and the processor is configured to instruct adjustment of the support platform to position the patient in a home position in the treatment room such that the target tissue is positioned at an isocenter of the treatment room according to the therapy plan, the platform position data, and a coordinate system transformation of the imager coordinate system to a room coordinate system of the treatment room.
11. 11. The system of claim 10, wherein the processor is configured to determine the coordinate system transformation based on imaging a dedicated imaging phantom comprising a plurality of markers disposed at known locations relative to the room coordinate system using the imager, by identifying a phantom marker in imaging of the imaging phantom, determining a phantom coordinate system in the imager coordinate system based on a location of the phantom marker, and determining a transformation of the imager coordinate system to the room coordinate system based on the phantom coordinate system and the known locations of the phantom marker relative to the room coordinate system.
12. 12. The system of claim 10, further comprising a positioning validator configured to validate positioning of the patient after moving the support platform to position the patient.
13. 13. The system of claim 12, wherein the positioning validator comprises a plurality of X-ray imagers in orthogonal alignment, and wherein validating the positioning of the patient comprises capturing a plurality of orthogonal stereo X-ray images, and adjusting the positioning of the patient based on the captured X-ray images.
14. 14. The system of claim 12, wherein verifying the positioning of the patient includes imaging the patient to generate a therapeutic imaging model, identifying differences between the therapeutic imaging model and a reference imaging model generated from the first imaging, and adjusting the positioning of the patient based on the identified differences.
15. 15. The system of claim 10, further comprising a platform adjuster configured to rotate at least one platform surface of the platform about at least one axis of rotation and to displace at least one platform surface of the platform along at least one axis of displacement.
16. 16. The system of claim 10, wherein the imager comprises a Computed Tomography (CT) scanner.
17. 17. The system of claim 10, wherein the imager comprises a movable imager configured to be sequentially repositioned and reoriented relative to a stationary patient to obtain a plurality of images at a plurality of imaging angles.
18. 18. The system of claim 10, wherein the patient support platform is a chair, and wherein the patient is in a sitting position.
19. 19. The system of claim 10, wherein the radiation therapy comprises proton radiation therapy.

Description

Patient positioning for fiducial marker-free radiation therapy Technical Field The present disclosure relates generally to the field of radiation therapy, and in particular to patient registration and platform alignment for radiation therapy without fiducial markers. Background Teletherapy is defined as a treatment method in which the irradiation source is at a distance from the body to be treated. X-rays and electron beams have long been used in telemedicine to treat various cancers. Unfortunately, X-rays exhibit a linear energy transfer that approximates an exponential decay function, and therefore are minimally safe for deep embedded tumors (deeply embedded growths). The use of heavy particles, particularly hadrons, more particularly protons, in telemedicine has been found to increase in acceptance due to their ability to penetrate to a specific depth without significantly damaging the intervening tissues. In particular, the linear energy transfer of a hadron exhibits an inverse depth profile, where a pronounced bragg peak is defined as the point where the hadron deposits most of the energy and occurs at the end of the hadron path. For electrons, the bragg peak is not observable due to high scattering. For protons with energies below about 70 MeV, scattering significantly suppresses the bragg peak. As a result of this effect, higher energy can be directed onto the embedded tumor than X-rays and electron beams that specifically damage the intervening tissue. While the term hadrons includes a broad range of particles, in practice protons and various ions are most widely used in therapy. For clarity, the treatment accomplished with protons will be described herein, however this is not meant to be limiting in any way. Protons or ions may be focused to a target volume of variable penetration depth. In this way, the dose distribution can be closely matched to the target volume with high accuracy. In particular, the proton beam may conform to the shape and depth of a target tumor (e.g., tumor) in order to avoid irradiating healthy body tissue while delivering a lower systemic radiation dose. Thus, proton therapy may allow for a stepwise increase in dose compared to conventional external beam therapy, which may be particularly beneficial for certain treatments (e.g. ocular tumors or skull base and paravertebral tumors). Proton therapy can also achieve high-precision treatment plans with reduced side effects, for example for pediatric treatment or prostate cancer treatment. To ensure complete illumination of the target mass, multiple beams are typically applied that reach the embedded mass from several different directions. The point at which the multiple beams intersect, whether the multiple beams are emitted sequentially or simultaneously, is referred to as the "isocenter (isocenter)". In order to maximize bioavailability, the isocenter must coincide exactly with the target tumor. Irradiation treatment of the target tissue is performed in a well-defined procedure. During an initial phase, the target tissue is imaged and a treatment plan is established. The treatment plan includes a series of treatment shots, each shot defining at least a dose parameter (dosage), a target tissue position and orientation, and an irradiation angle for each irradiation dose. Prior to imaging and treatment planning, the coordinate system of the imaging device is reset, for example, by a radiation therapy technician, in the vicinity of the target tissue. Placement or fiducial markers are defined relative to the patient based on imaging device initialization coordinates for guiding the positioning of the patient in the treatment. Multiple fiducial markers, such as markers applied to the patient's skin or a fixed accessory, such as a set of three markers, are typically applied to achieve three-dimensional (3D) positioning. The markers may be formed or highlighted using non-erasable markers or radio-opaque materials to facilitate their visualization on the imaging device. The indicia is typically designed to last at least a minimum period, such as weeks or months, to last throughout the duration of the planned treatment. For example, the fiducial mark may be in the form of a dot-like ink tattoo. In a subsequent stage, in response to the formulated treatment plan, irradiation is performed in multiple treatment sessions over a period of time. During treatment care must be taken to ensure proper positioning of the patient relative to the fiducial markers in order to ensure that the applied irradiation dose is properly targeted and to avoid injuring organs in the vicinity of the target tissue. Positioning of the patient relative to the markers is performed based on visualization of the patient relative to the defined markers. During a treatment session, the patient is displaced to an initial setup position by positioning a platform supporting the patient such that the fiducial markers converge with the isocenter of the treatment room. Treat