High-Precision Treatment

Aizawa Hospital provides High-Precision Proton Therapy

Proton Therapy Center at Aizawa Hospital has been making various endeavors to maximize the unique behavior of protons and provide radiation therapy with high precision in an effective manner for patients.

Irradiation Methods

More precise irradiation using new technology is available in addition to standard broad beam irradiation.

Broad Beam Irradiation (Standard method)

A method of irradiation by uniformly enlarging the diameter of beams and shaping them into the shape of a targeted tumor using a beam shaping device made specifically for individual patients, referred to as a collimator and a bolus. Protons deliver a large burst of energy at a precise depth and then stop completely according to the treatment plan created by a physician. Thus, proton therapy enables to avoid irradiating important tissues beyond the tumor.


Adjusts the depth of proton beams

Patient Collimator

Adjusts the width of proton beams

New Technology: Pencil Beam Scanning

Proton therapy is generally performed with broad beam irradiation method. This irradiates the whole tumor all at once, which enables adjusting depth accurately while having difficulties adjusting superficial side.
Aizawa Proton Therapy Center has added one of the most advanced technologies, Pencil-Beam Scanning technology, in order to offer more precise proton therapy for our patients. Proton therapy delivered with Pencil Beam Scanning allows doctors to "paint" the tumor with an ultra-narrow proton beam tuned to a precise range, as well as adjust the intensity of the beam to achieve the desired dose distribution. Using this technology, intensity modulated radiation* can be performed with proton beam, which enables us to treat with more precision.

Intensity Modulated Radiation
With this radiation method, irregular shaped tumors can be treated by modulating the intensity of radiation to form it into the shape of tumor. By forming radiation into the shape of the tumor, influence of radiation to the healthy tissues can be reduced.
Tomotherapy, which has been already introduced at our hospital, is one of the intensity modulated radiation therapy equipment with x-ray.

Respiration-Gated Irradiation (Irradiation for moving organs due to breathing)


Although proton beam can irradiate a tumor at a pinpoint, it loses effectiveness when there is a position gap. Therefore, “Respiration-Gated Irradiation” is available for treating a tumor that moves as the patient breathes, such as a tumor in lungs.
Proton beam is delivered only when a tumor is exactly in the right place by synchronizing the timing of irradiation with respiration cycle. In this way, a tumor in moving organs can be treated with high precision.

Our Gantry Room

Provide high-precision proton therapy with high-accuracy positioning using advanced devices

To accomplish high-precision treatment in radiation therapies including proton therapy, it is critically important to accurately determine the position, size, and shape of a tumor.

At Aizawa proton therapy center, physician can adjust the position of the target site by millimeter by superimposing the images of a treatment plan on the images obtained from X-ray and CT machines in the treatment room just before treatment.
Furthermore, a treatment table is controlled with robotic system and it moves between treatment area and In-Room CT, therefore a patient can stay in the same position.
Using equipment like this, we accomplished to offer more precise proton therapy for our patients.

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