HALCYON is a new generation radiotherapy device, which was installed in ONKOMER for the first time in Turkey and can perform all kinds of modern radiation therapy. It is a special high-modulation radiotherapy device that combines Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) methods, and 100% image guidance (IGRT) in a single device. It provides all kinds of ideal modern radiotherapy applications from point irradiations to long field irradiations, from deep organ tumors to superficial cerebral tumors.
Unlike C-arm linear accelerators, HALCYON has the opportunity to increase both the IMRT areas and the number of arcs. Therefore, the dose intensity change potential is much higher than other radiotherapy devices. With its rapid imaging and treatment feature, it provides more patients to be taken and provides an efficient study by shortening the treatment time.
Treatment Methods Performed with Halcyon System
Volumetric modulated arc therapy(VMAT): In this technique, the shape of the multi-leaf collimator (MLC-Multi Leaf Collimator) is changed to suit the shape of the area to be irradiated, and normal organs are perfectly protected every 2 degrees of device rotation. Dose intensity can be modulated as desired by supporting full or partial arcs with variable dose rates throughout the movement of the device body (Gantry).
Intensity-modulated radiotherapy (IMRT): It can perform both dynamic and static IMRT. Dynamic IMRT; MLC leaves move continuously to deliver dose-intensity-adjusted radiotherapy. Static IMRT; The system stops at every step and gives a beam. These steps go up to 500 segments.
Point treatments: Even targets smaller than half a centimeter can be treated with this system with full accuracy, protecting the organs at risk. It can do this both in the brain and even in parts of the body with respiratory movement, visceral movement.
SRS (Stereotactic Radiosurgery): Single session point radiotherapy.
SRT (Stereotactic Radiotherapy): Multi-session point radiotherapy.
SBRT (Stereotactic Body Radiotherapy): Stereotactic body radiotherapy.
IGRS (Image Guided Radiosurgery): Image-guided radiosurgery.
Image-Guided Radiotherapy (IGRT): During the treatment, the differences in respiration change and organ movement are determined quickly. The device is capable of combining these images with the planned areas and giving the treatment exactly as planned. Smaller margins are given to the clinical target volume. During the treatment, as planned with image guidance, the organs at risk are fully protected and the planned area receives the full dose. SBRT, SRT, and SRS are used more effectively in hypofractionated radiotherapies as target sensitivity is at the maximum level. The image-guided accuracy and speed of HALCYON provide great safe comfort to the patient.
Superficial Treatments: With the Electronic Compensators technique, skin cancers can be treated, as well as in cases where it is necessary to change the surface dose density. For example, it is possible to reduce the skin dose in breast treatments or to increase the superficial radiation dose in cases with mastectomy without using boluses. It can provide a superficial treatment with sensitivity to treat skin cancer in the nose wing without a nasal cavity problem.
Large field irradiation: It can perform treatment of all sizes from craniospinal irradiation to whole-body irradiation.
Halcyon's Difference from Other Radiotherapy Devices
VMAT difference: Varian systems provide accurate modulation arc treatment with 3 technical parameters: Dose rate, MLC positions, and Device body speed.
Dose Rate: There is a special "triode" electron gun in the beam generation system. Dose rate can be changed instantly on Varian treatment delivery platforms. Thanks to its special algorithm, it easily reaches the highest possible dose rate and dose rate.
New generation MLC leaves: In HALCYON's new generation MLC (Multi Leaf Collimator), overlapping and completely interlocking gradual leaves can create independent movements. The leaves have a low photon permeability of 0.01%, a length of 16 cm, and a tungsten structure. With these new generation MLCs, it is possible to make thinner area shaping and to create maximum dose modulation. Rounded and jagged edges are shaped more easily.
Device Body (Gantry) Speed: Varian HALCYON, the gantry speed can reach 4 RPM, that is, 4 rotations per minute during the treatment. The motors used in the HALCYON device allow faster, smoother, and quieter gantry speed transitions. During radiation therapy, especially in rotational treatments, the dose rate, gantry speed, and MLC speed in the device affect the treatment time. The HALCYON system has a gantry rotation at a speed of 4 RPM per minute. This device speed shortens the treatment time and if the mask, vacuum beds, etc. used to fix the patient are taken into account, the shortening of the treatment time provides great patient comfort.
HALCYON and Tomotherapy Difference
Treatment speed difference: The tomotherapy device is slow in the treatment speed due to the fact that the movement of the table is taken into account during the helical treatment. In comparison studies, Halcyon has the lowest treatment time compared to both IMRT and Helical IMRT.
Modulation quality difference: The collimation system, which makes beam shaping, has different technologies in both devices and aims to achieve sufficient dose density modulation with rotational density-adjusted radiotherapy. MLC thickness and MLC sealing values are very important in order to distinguish between tumor and critical organs more successfully in terms of treatment quality.
Tomotherapy system has 64 pneumatically operated MLC systems with 0.25% permeability and 0.625 cm thickness at the isocenter. In Halcyon, the sealing of the leaves is better and the leaf thickness is less. The beam permeability of the leaves is 0.01%, the thickness is 0.5cm, and the new generation double layer feature. The independent movements of the double-layered, stepped leaves create finer field shaping, and changing the dose density is more successful.
The difference in irradiation of large treatment areas: Clinical situations where long treatment areas are used; Craniospinal irradiation (eg medulloblastoma), whole-body or total bone marrow irradiation, pelvic treatments for advanced-stage cancers (eg cervix or full abdominal irradiation), breast cases with supraclavicular glands, common thoracic cases, etc.
In the treatment of long areas, if the field is longer than the field opening in standard linear accelerators, an isocentric treatment in a single plan is not possible and the field junctions are a problem because a large number of fields are combined with separate plans. The doses of the field junctions can be either missing or excessive. In the daily treatment of the patient, one more set-up is performed and the treatment period is prolonged. However, with HALCYON, no matter how long the treatment area is, the whole area is treated at one time with the gradually optimized multi-plan treatment.
In the Varian HALCYON system, the target length is treated in a single plan for targets with a length of less than 38.5 cm, and multiple plans are gradually optimized for longer targets. As a result, any length of treatment can be performed. Thanks to the Varian Eclipse 16.0 planning system feature, which can assign two isocenter in a single plan, the patient can be treated in the desired size without the need for additional set-up. With this system, long treatment areas are extremely easy.
The IGRT difference in HALCYON
In the Halcyon system, it is possible to take both 3-dimensional and 2-dimensional images in patient imaging. Computed tomography film used for three-dimensional forms the basis of image guided radiotherapy (IGRT). With the reconstruction of the volumetric images taken while the device rotates around the patient between 180 and 360 degrees, a 3-dimensional image is obtained and compared with the reference planning images. Halcyon has the ability to take both KV-CBCT (Kilowoltage tomography) and MV-CBCT (Megavoltage tomography) films. With kilovoltage imaging systems, it is better to show soft tissues. Halcyon can get these images in seconds. Three-dimensional KV-CBCT images can be created in 17 seconds, and MV-CBCT imaging in 15 seconds. In the 2-dimensional imaging option based on the bone structure, images can be obtained within 7 seconds and treatment can be started quickly. The speed in the control of the treatment areas gives Halcyon a great advantage. For example, the time spent in a door-to-door prostate patient treatment is 6-7 minutes. Only 2 minutes of this pass during radiation therapy.