Before the advent of analog positioning machines, ordinary diagnostic x-ray machines were used

In the late 1960s, X-ray simulation positioning machines were used in clinical radiotherapy

Treatment technology where the isocenter falls on the surface of the skin or body membrane

Advantages: Simple and easy to use, intuitive and reliable

Disadvantages: limited to bone metastasis, skin surface and other diseases, unable to treat esophageal cancer, gastric cancer, lung cancer and other tumors

Also called isocenter technology, this center point is the intersection point of the rack rotation axis, the bed isocenter rotation axis, and the collimator rotation axis. Place the patient's tumor center at this isocenter during treatment

Advantages: accurate positioning of deep tumors, simple and comfortable patient position, easy fixation and good repeatability

Target area and important organ positioning

Determine the range of motion of the target area

Treatment options

Outline radiation fields and positioning/positioning reference markers

Take radiation field positioning or confirmation films

Check the shape and position of the radiation field block

Assist patient position fixation

Realize target area positioning

Make marks for reference in outlining the field of view, positioning and positioning

Take plain films of the field of view and design lead blocks

Attach therapeutic accessories during verification and simulation

Compare with the corresponding field direction view given by the treatment planning system

Measure target depth

Carry out other clinical work

Test simulated positioning and various data accuracy

Check the accuracy of the isocenter of the field of view and the laser device

Ensure patients receive accurate positional repetitions

The main axis of the head and body is parallel to the longitudinal axis of the treatment bed and perpendicular to the center beam of the irradiation field.

Use a special pillow with a special height and number, keep your chin as close as possible, and use the line connecting the eyebrow tubercle and the external ear hole perpendicular to the bed surface as the benchmark

Place the center of the light indicator field at the intersection point slightly above the midline of the body and the horizontal line of the eyebrow arch.

For the source-to-skin distance (100cm) and radiation field (4cm×4cm-6cm×6cm), adjust the center position through fluoroscopy so that the radiation avoids the orbit.

Rotate the large gantry to 90°, raise the bed appropriately and place the center of the radiation field in the pituitary fossa through fluoroscopy. The central axis of the radiation field should be parallel to the cranial baseline. You can turn the handpiece smaller and move the bed longitudinally to make the radiation field reach requirements, record the small handpiece angle and tumor depth

Tumor depth=100cm-source skin distance

Draw a marking line, and then turn the large frame 180° to the opposite side. The positioning method is the same as the opposite side.

Temperature and humidity: The computer room temperature is 18~24° (±5°), the humidity is controlled at 30%~60%; the operating room temperature is 18~28°C (±5°C), and the relative humidity is 20%~80%

Turn on the CT machine

Check that the disk storage space of the CT positioning machine is sufficient

Turn on the high-pressure syringe power

Ct laser calibration

Inspection of Ct indoor fixtures

Preparation of emergency medicines and equipment

Check the patient’s positioning request form

Uncooperative patients

Patients whose sutures were not removed after surgery

Patient positioning and immobilization

Scanning plan

Scan range

contrast agent

Special considerations and guidance

reference mark

virtual simulation

Flag treatment plan results

Each scan is in the same respiratory phase and needs to be coordinated with respiratory gated radiotherapy.

Collect images of all respiratory phases, observe the range of movement of the target area, and formulate personalized PTV for targeted radiotherapy (more applications)

Magnetic resonance has high resolution for soft tissue, but the image is distorted and there is no electron density information required for dose calculation. Fusion with CT can clarify the location and extent of the tumor