MindMap Gallery Medicine-Introduction to Radiation Therapy Technology
Radiotherapy technology, radiotherapy is an important branch in the medical field. It mainly uses radioactive substances and electromagnetic waves and other technologies to diagnose and treat the human body.
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Introduction to Radiation Therapy Technology
A brief history of the positioning and development of radiotherapy disciplines
Subject positioning
A brief history of subject development
A brief history of the development of Chinese disciplines
Radiation Oncology Fundamentals
Basic composition of disciplines
clinical oncology
radiotherapy
The main research is on the specific use of various radioactive sources and equipment to treat tumor patients, including technical implementation such as visual field configuration, positioning, and fixed positioning operations.
radiation physics
Mainly studies the performance and characteristics, dose and protection of various radioactive sources
radiobiology
It mainly studies the response of normal tissues and tumor tissues of the body to radiation and how to artificially change these responses to ensure the harmonious dose of radiotherapy.
Computers, Diagnostic Imaging and Anatomy
multidisciplinary comprehensive treatment
Radiation therapy and surgery: preoperative radiation therapy
Radiotherapy and Chemotherapy
Surgery, radiotherapy and chemotherapy
Radiotherapy and endocrine therapy
Radiation therapy and targeted therapy or immunotherapy
Surgery and Chemotherapy
Radiotherapy Standard Operating Procedures
Radiotherapy standard operating procedures
History and physical examination
Determine clinical characteristics and tumor extent
radiation oncologist
Clinical stage
Standard periodic inspection
radiation oncologist
clinical diagnosis
Determine clinical and pathological diagnosis and perform clinical staging
radiation oncologist
Determine overall treatment principles
Single or combined treatment
radiation oncologist
Determine radiotherapy principles
Radical, palliative or salvage radiotherapy
radiation oncologist
Determine radiotherapy technique
Choose radiation technology, conventional radiation, three-dimensional conformal radiation, intensity modulated radiotherapy, brachytherapy
radiation oncologist
Treatment plan development
After simulating positioning (technician), outline the normal tissue in the target area to determine the gtv, ctv, ptv prescription doses and normal tissue limit doses.
radiation oncologist, technologist
treatment plan design
Design the radiation field, optimize the treatment plan, select the appropriate radiation technology and calculate the best solution
Physicists and Physicians
Treatment plan verification
Accuracy of simulation verification or other verification programs
physicist, physician, technician
Treatment plan execution
Position the accelerator, take verification photos, and check treatment orders
physicist, physician, technician
accelerator therapy
Accelerator irradiation patient, weekly positioning verification
technician
Observe during treatment
Check treatment orders every week, examine patients, observe efficacy and record toxic and side effects
Physician, technician, nurse
Quality control and assurance
Perform quality assurance and quality control on instruments and equipment
Physicists and Technicians
Follow up
Develop a follow-up plan and follow up with patients regularly after treatment
radiation oncologist
Observation of long-term efficacy and toxic and side effects
Establish clinical and physical databases, calculate survival rates and observe side effects, and continuously improve treatment methods and technologies
radiation oncologist
Positioning and fixing
Position: supine, prone, special position
Fixation: body membrane, head, neck and shoulder membrane, vacuum pad Headrest A, B, C, D, E, F, boat-shaped pillow, head, neck and shoulder frame, body frame, perforated web
Special treatment: no food, no water, holding urine
Target volume definition and plan description
Tumor area (GTV)
Clinical target volume (CTV)
Inner target volume (ITV)
Planning target volume (PTV)
Organs at risk (OR)
The status and role of radiotherapy
status and role
Currently, there are more and more treatments for tumors, but surgery, radiotherapy, and chemotherapy are still the three most effective main treatments.
effect
Indications
Head and neck squamous cell carcinoma, chest tumors, breast cancer, lymphatic system, tumors, digestive system, tumors, urinary system tumors, nervous system tumors, bone tumors Certain benign diseases such as eosinophilic granuloma, certain hemangiomas, keloids, prostatic hypertrophy, ankylosing spondylitis, etc.
Contraindications
General condition
When the functions of important organs such as the heart, liver, and kidneys are severely damaged
Severe systemic infection, sepsis, uncontrolled sepsis
Before treatment, hemoglobin is lower than 80g/l and white blood cells are lower than 3.0×10 9/l and have not been corrected.
Those with advanced cancer, anemia, weight loss and cachexia
Tumor status
The tumor has spread extensively in the late stage, and the tumor is not sensitive to radiation, and radiation therapy cannot improve symptoms.
When the organ where the tumor is located has perforation, comatose patients have a large amount of pleural effusion, which may lead to perforation and massive bleeding.
Tumors that are radioinsensitive should be considered relatively contraindicated
Radiotherapy status
Have had radiotherapy recently (within six months)
Skin or local tissue fibrosis, local ulcer pathological examination is negative, and other serious injuries that do not allow further radiation therapy
radical radiotherapy
Giving the tumor a lethal dose of irradiation causes the tumor to shrink and disappear within the treatment area, achieving the effect of clinical cure. The patient can achieve long-term survival. Radiotherapy may occur during or after treatment. Toxic and side effects are inevitable, but should be controlled. within acceptable range
The general condition is good/the local tumor is large and there is no distant metastasis/it is a radiosensitive or severely sensitive tumor
The radiation field includes all primary tumors and necessary lymphatic drainage areas/the radiation dose is large and surrounding normal tissues and organs need to be protected
palliative radiation therapy
Radiotherapy based on the radical dose cannot eliminate the survival of tumor patients with tumors. It is a radiotherapy method that only aims at alleviating the patient's pain and relieving symptoms.
Mainly targeted at patients with advanced tumor stages and difficult clinical cure.
Relieve symptoms and reduce pain/Although it cannot prolong survival, it can temporarily inhibit tumor growth/Reduce the psychological burden of patients through simple treatment
Highly palliative radiotherapy
The tumor is more extensive, and patients with better general conditions can be given a curative dose. Or radiotherapy at a dose close to the radical cure can achieve better clinical efficacy in some patients.
low palliative radiotherapy
Patients with poor general conditions can be given a radical dose or a low-fractionated dose, and simple irradiation techniques can be used. Avoid causing pain to patients due to complicated taste arrangements
Function: relieve pain, relieve compression, stop bleeding, promote control of ulcerative cancer lesions, and improve quality of life
preventive radiation therapy
It is mainly targeted at irradiation of subclinical lesions. In clinical practice, preventive radiotherapy is often used for patients with high-risk local recurrence risk factors after radical surgery for malignant tumors. The purpose is to improve the local control rate.
Radiation therapy for non-malignant disease
Non-malignant or benign diseases can be successfully treated by radiation exposure and are mainly divided into inflammatory, degenerative, proliferative and functional types.
The role of advanced radiotherapy technology
Preoperative treatment
Purpose
Inhibit tumor cell activity - Prevent tumor cells from planting and spreading during surgery - Control microscopic lesions around tumors and transfer lymph nodes - Reduce tumor size - Facilitate resection - Eliminate inflammation and ulcers associated with tumors - Reduce symptoms and improve patients status to prepare for surgery (increase resection rate)
Indications
The tumor location is deep, the tumor body is large, the tumor has obvious infiltration and adhesion to the surrounding area, and there are multiple local lymph node metastases, making it difficult to completely remove it with surgery.
Lung cancer, esophagus cancer, stomach cancer, rectal cancer, bladder cancer
dose
Low-dose short-term radiotherapy, dose 15~20gy/3~10 days
Moderate dose conventional radiotherapy dose 30~40gy/3~4 weeks
High dose conventional radiotherapy dose. 50~60gy/5~6 weeks
intraoperative treatment
For patients who cannot be resected or whose resection is incomplete, a large dose of radiation will be given during the operation.
Indications: Tumors that grow or are closely related to large blood vessels, have infiltration into organs, cannot be completely resected, and are likely to have residual or residual tumors after surgery Commonly used for cholangiocarcinoma, gastric cancer, pancreatic cancer, prostate cancer and osteosarcoma, etc.
Advantages: The tumor can be fully exposed, the target area is clear, and normal tissue can be well protected. Large doses can cause high biological effects and shorten the course of treatment.
Disadvantages: For one irradiation, it is difficult to determine the most suitable irradiation dose, the biological advantages of conventional segmentation are lost, the equipment is expensive, and radiation shielding is difficult
Postoperative treatment
Purpose: Reduce local recurrence rate and improve survival rate
Postoperative radiotherapy time: Generally, radiotherapy is performed as soon as possible 2 to 4 weeks after the operation. One month after the operation for head and neck tumors is the best period. Postoperative chemotherapy for breast cancer is performed after 2 to 3 weeks. Radiotherapy must be performed as soon as possible after the operation for rectal cancer. Reduce sacrococcygeal recurrence rate
For those with high-risk recurrence factors, concurrent chemoradiotherapy can be performed
Indications: Brain glioma, head and neck tumors, lung cancer, esophageal cancer, rectal cancer, kidney cancer, bladder cancer, prostate cancer, seminoma, breast cancer, cervical cancer, endometrial cancer, bone-soft tissue sarcoma
Internal and external radiation
radiotherapy technology
teleradiation therapy
Ordinary x-ray therapy machine
High-speed moving electrons act on heavy metal targets such as tungsten to produce X-rays, contact X-ray machine 10-60kv/shallow layer
Features: Mainly used for treatment or preventive irradiation of body surface tumors or superficial lymph node metastasis tumors
Cobalt 60 treatment machine
Principle: Use r-rays (average energy 1.25MeV) emitted by the isotope cobalt 60 to treat tumors
Features
It has strong penetrating power, high depth dose, and low skin dose. The maximum energy absorption occurs at 4~5mm under the skin.
Bone and soft tissue absorb doses equally
Simple structure and easy maintenance
Disadvantages: Penumbral area, need to change source, protection is not as safe as X-ray
source-to-skin radiotherapy technology
principle
Fixed distance from radiation source s to skin ssd
The center t of the tumor or target area is placed on the line connecting the two points of the radiation source and the skin entrance point.
The therapeutic myocenter a is placed on the patient’s skin
Advantages: Simple positioning and easy positioning
shortcoming
Poor treatment accuracy
The gantry angle must be accurate and the patient's position must be accurate (otherwise the tumor center will easily escape from the central axis of the radiation field or outside the radiation field)
conventional radiotherapy techniques
develop
Two dimensions - three dimensions - four dimensions
Ordinary radiotherapy - conformal radiotherapy - intensity modulated radiotherapy - image guided intensity modulated radiotherapy - dose guided intensity modulated radiotherapy
Isocenter irradiation technology/source axis distance irradiation technology
principle
Place the isocenter a of the treatment machine above the center t of the tumor or target area. No matter how the frame is rotated to any angle, the central axis of the ray can be aligned with the target center. The distance sad from the radiation source to the tumor is fixed and equal to the rotation radius of the machine.
advantage
As long as the isocenter is at the center of the tumor or target area t, regardless of the accuracy of the gantry angle and the error of the patient's position, it can ensure that the central axis of the field of view passes through the center of the tumor or target area, with high efficiency, high precision, and good dose distribution.
shortcoming
The positioning is complicated and the bed must be raised accurately
Stereotactic radiosurgery for the treatment of SRS
It refers to a single irradiation in which high-energy radiation is concentrated on a certain limited target area, causing a radioactive reaction to occur while the surrounding tissue outside the target area is reduced as quickly as possible to avoid being affected, thereby forming a knife-like interface at its edge to achieve a similar surgical effect. The effect of surgery
SBRT uses high-dose radiotherapy each time. In just a few irradiations, it can achieve a radical dose to eliminate tumors, so it is also called stereotactic ablation body radiotherapy.
Gamma knife treatment process
Installing the stereotaxic headframe
Imaging positioning
Set up a treatment plan
localized radiation therapy
stereotactic radiosurgery
Tano, Ono cluster, stereotaxic, single high-dose irradiation
Three-dimensional conformal radiotherapy 3DCRT
Stereotactic, conformal, fractionated irradiation
Precision radiotherapy technology
X knife: less than or equal to 3cm
r knife: less than or equal to 3cm
Three-dimensional conformal radiation therapy: greater than 3cm
Three-dimensional conformal intensity-modulated radiation therapy: concave lesions with irregular shapes that surround normal tissue
TOMO: There is no limit on the size of the treatment range and the location of the tumor. Multiple target areas can be irradiated simultaneously. The most complex whole body treatments can be achieved (diameter up to 150cm, cross-sectional diameter up to 60cm)
Linear accelerator: A device that uses microwave electric fields to accelerate electrons in a straight line and then emits x-rays or electron rays to treat tumors.
Can emit electron beams of different energies to treat superficial and eccentric tumors
Energy can be selected as needed
The radiation field is convenient and the dose in the radiation field is uniform.
Disadvantages: Complex maintenance
rotational irradiation technology
method
A treatment technology that uses the center of the tumor or target area as the center of rotation and moves the radioactive source around the patient for irradiation.
It can be viewed as countless isocenter field irradiations at fixed angles.
advantage
Same as SAD technology, with high central dose and low surface and normal tissue dose.
shortcoming
Complex placement
Three-dimensional conformal radiation therapy
principle
Advantage
Reduce the range of tissues and organs surrounding the tumor that enter the radiation field, protect normal tissues, and increase the radiation dose in the target area.
For tumors with complex anatomy and close to important organs, it has obvious advantages in reducing the occurrence of complications.
High-dose low-fractionation irradiation can be performed to shorten treatment time and improve tumor control rate.
Three-dimensional intensity modulated radiotherapy
principle
Imrt technology requires decomposing a beam of rays into hundreds of small rays to adjust the intensity of each beam individually. The rays are irradiated in a complex form that changes in time and space.
The shape of the irradiation field is consistent with the irradiation target area
The dose within the target area reaches satisfactory distribution requirements
Image Guided Radiation Therapy IGRT
Four-dimensional radiation therapy is a radiation therapy technology that uses image guidance to reduce changes in tumor location due to positioning or organ movement. Realize automatic tracking and automatic positioning of the target area during treatment
There is a problem
Positioning error of fractionated treatment
Target displacement and deformation between fractions
Target movement in the same fraction
solution
Online school position
adaptive radiotherapy
Breathing and breathing gating technology
Four-dimensional radiation therapy
Track treatment in real time
Proton and Heavy Ion Therapy Imaging
brachytherapy
form
Intracavitary irradiation
Intracavitary post-loading technology: It is to place the unloaded source container (rigid tubular, flexible, needle-shaped) in a suitable position in the uterine cavity and vagina, and then use mechanical control methods under protective shielding conditions. A technology that transports radioactive sources from a source tank through a pipeline into a source container for radiotherapy
Intratube irradiation
intertissue irradiation
inter-tissue interpolation technique
Apply irradiation
Strontium-90 radiotherapy
radioactive seed implantation therapy
Iodine-125 seed implantation
radionuclide therapy
effect
Improve survival rate
Reduce side effects
Change dose fractionation irradiation mode
Expand indications for radiotherapy
reduce risk
Concurrent chemoradiotherapy for tumors
Purpose
Improve local control rate
Reduce local recurrence rate, improve patient survival rate, and improve quality of life
Reduce the rate of distant metastasis
Preserve organ integrity and normal function
Joint theoretical basis
spatial collaboration
Radiation therapy - localized, chemotherapy - systemic
Toxicity is non-additive or minimal
Chemotherapy drugs and radiotherapy sensitization
Platinum, taxanes, pyrimidine analogs, topoisomerase inhibitors
Chemotherapy drugs inhibit DNA repair
cycle synergy
Some chemotherapy drugs block the cell cycle in the M and G2 phases
Protect normal tissue
Chemotherapy reduces tumor size and reduces the scope of radiation therapy
Use together
Sequence of radiotherapy and chemotherapy
Selection of chemotherapy drugs and doses
Radiation therapy field
Radiation therapy time dose division method
Prevention and treatment of adverse reactions
Radiation protection and emergency response during radiotherapy
personal dosage limits
Staff dose limits
Limit value 20ms v/a
public
Limit 1msv/a, measurement constraint value 0.25msv/a (nuclear power plant)
Provincial Environmental Protection Department Radiation Safety License Acceptance and Approval Procedure
Unit qualification recognition
External radiation protection measures
Depending on the type of rays, materials with different properties can be selected for shielding protection. For X and R rays, lead, iron, cement, concrete, bricks, stones, etc. can be used.
Aluminum, glass, plexiglass, etc. can be used to protect B rays (Renzhi)
Neutron protection can be achieved with paraffin and water
Stay away from radiation sources and reduce stay time
Radiation protection measures
Time - the shorter the time of exposure to radiation, the smaller the dose to the body
Distance - the further away from the radiation source, the lower the dose received
Shielding, lead sheets, cement walls, water can all block radiation or reduce radiation intensity