1. What is photon knife?
Photon knife, shorted for photon isotron system, is a medical approach to kill tumor cells by photon radioactive ray. It is named as photon knife due to its equal effects as surgery.
As one of latest high technologies in international radiotherapy community, the biggest advantage for photon knife lies in three dimensional, oriented and conformal radiation. It is capable of precisely and automatically shaping radiation field for irregular tumors to reduce radiation dose to normal tissue surrounding tumor, increase dose for targeted tumor region and to minimize complications.
2.Treatment procedures
Step 1: tumor location -- ---determine exact position and scope of tumor and surrounding vital organs under guidance of dimensional oriented devices, CT scan, MRI, digital subtraction radiography or by three dimensional reconstruction techniques. The process is called three dimensional positioning.
Step 2: plan design-----optimal treatment plan is made including accurately calculated lesion division and dose distribution of surrounding vital organs.
Step 3: accurate therapy---- photon radiation with various energy is applied based on size, location and depth of tumors to make energy accessible to deep layer of tumor. This results in congestion, swelling and necrosis of lesion tissues until dead cells are absorbed, decomposed and excreted by surrounding normal tissues.
3. Advantages of photon knife therapy
Photon knife Vs. Conventional radiotherapy
Photon knife：
Multiple co-planes are set based on dimensional shape of tumor for an overall attack to tumor tissue.
Accumulated dose of multiple co-plane radiation makes it easy to reach fatal dose to kill tumor.
Conventional radiotherapy：
Tumor is usually surrounded by normal tissues. Therefore, single planar dose will kill tumor as well as normal tissue surrounding tumor when it reaches fatal dose.
Photon knife Vs. Surgery
Photon knife：
Avoid surgery, bleeding, suffering and risks.
Photon radioactive ray cause death of tumor tissue inside human body and minimize incidence of infectious complications.
It can be applied to many vital sites where surgery is not allowed, such as beside great vessels of the heart, hilum of lungs and recurrent adhesive parts after surgery.
Surgery：
Must go through bleeding, bitter suffering and risks.
Total resection of tumor can not be achieved in irregularly shaped tumor.
Implanted tumor may occur due to tumor implantation to normal tissue in tumor cutting and removal.
Photon knife：
Mulitple fields, multiple angles and comformal radiation are performed exactly to tumor tissue under the control of modernized computer, with low rates for side effects on normal tissues.
Vs. Conventional chemotherapy
Chemo-drugs bear toxic effects and result in damage to blood and lymph node cells of immune defense system and worsen immune system while they kill tumor cells.
4. Clinical applications
It applies to tumors inside skull and neck, thoracic tumors, abdominal tumors, pelvic tumors, soft tissue sarcomas, osteosarcoma and more. It is considered as the optimal choice for patients unable to undergo surgery, with residual tumor or recurrent tumor after surgery, or for those unable to tolerate surgery and with recurrent tumor followed by conventional radiotherapy, chemotherapy.
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