Navigational Helical Knife, also known as Helical Tomotherapy Radiation Therapy System, also known as TOMO for short, is a 6 megavolt (MV) medical linear gas pedal’s main components installed in the 64-row helical CT’s sliding ring frame, with the helical CT rotary scanning mode, combined with high-tech computerized tomography image navigation and tuning, and through 360-degree rotation, the 51 arcs of irradiation, so as to achieve the dose distribution requirements within the range of 40 cm × 160 cm, irradiation of various distributions, locations and shapes of tumors within this range, is considered to be one of today’s most advanced radiation therapy equipment for tumors, integrating intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), adaptive radiotherapy (ART) and DGRT (dose-guided radiation therapy). (IMRT, IGRT, ART and DGRT). TOMO was officially launched in the U.S. in 2005 and has been rapidly recognized by the international radiotherapy community, with more than 1,500 international clinical papers and reports recognizing the advancement of its technology platform and its clinical efficacy. More than a dozen papers are published every year in the top journals in the field of radiotherapy, and new research in the field of clinical application is continuously carried out. At present, nearly 500 TOMOs have been installed worldwide and hundreds of thousands of patients have been treated. A large number of world-renowned oncology centers have been equipped with multiple navigation helical knives. These top hospitals include M.D. Anderson Cancer Center, the largest cancer center in the U.S., University of California, San Francisco, City of Hope in Los Angeles, Swedish Medical Center in Washington, D.C., U.C. DAVIS, National Cancer Center in Heidelberg, Germany, Curie Institute in France, National Cancer Institute in Singapore, and the National Cancer Institute in Singapore. Institute, National Cancer Center (NCC) in Singapore, National Cancer Center (NCC) in Korea, Yonsei University, National Taiwan University Hospital, Veteran’s General Hospital, Tata Medical Centre in India, and many other world-renowned hospitals and oncology centers. Due to the unique technical features and platform of TOMO, it breaks through the many limitations of traditional precision radiotherapy, expands a new direction and future for radiotherapy, and may rewrite many clinical indications of radiotherapy, which is inextricably linked to its structural features, as described below. 1.Slip ring frame structure and spiral irradiation mode The HT’s fan-shaped ray irradiation field can be rotated around the center of the machine 360°continuously, and at the same time, the treatment bed along the center of the bed, the irradiation field rays around the patient to produce a spiral irradiation flux map, continuous spiral irradiation not only solves the problem of the dose inhomogeneity of the layer-to-layer interface, and at the same time, it can also achieve continuous irradiation of the long target area, and the maximum length of the target area can reach 4000px. The maximum length of target area can be up to 4000px. 2.Pneumatic binary multi-leaf grating HT adopts pneumatic binary multi-leaf grating design, with a blade width of 0.625cm, 64 pieces in total, and adopts the interlocking design to modulate the irradiation field into a width of 1000px. Binary means that during the treatment process, the blades have two states of on and off, and its on/off switching time is only 20 milliseconds, which can modulate the intensity of subfield through the switching time, and the motion sequence and opening/closing time of the blades completes the modulation of the intensity of the subfield, so that it realizes the ability of 100-fold modulation of the intensity in the direction of 51 irradiation fields. Based on the above technical characteristics, compared with conventional linear gas pedals, the HT system has the following advantages: its use of volumetric intensity-modulated rotation technology, with non-uniform intensity rays, different intensity level difference, to achieve the best conformal and dose uniformity, to achieve the dose in the target area of the expected design scheme; 3, MVCT online image correction and dose verification HT’s linear gas pedal, in addition to the emission of a 6MV fan beam X-ray for In addition to emitting 6MV fan beam X-rays for treatment, the HT linear accelerator can also emit 3.5MV fan beam X-rays, which produce megavolt-level 3D CT images (MVCT) by helical scanning. This is not only used for positional validation and calibration of the patient prior to treatment, to correct the posing error, but also for calculating the actual dose distribution of the same day’s irradiation, which is used to evaluate and adjust the plan for the subsequent fractionated treatments, making it easy to realize the Adaptive Radiation Therapy (ART) and the Dose-Guided Radiotherapy (DGRT). DGRT). As a result, HT has a wide treatment range, a high degree of automation in treatment positioning and verification, and takes less time.