Performance of the NIRS fast scanning system for heavy-ion radiotherapy.

PURPOSE: A project to construct a new treatment facility, as an extension of the existing HIMAC facility, has been initiated for the further development of carbon-ion therapy at NIRS. This new treatment facility is equipped with a 3D irradiation system with pencil-beam scanning. The challenge of this project is to realize treatment of a moving target by scanning irradiation. To achieve fast rescanning within an acceptable irradiation time, the authors developed a fast scanning system. METHODS: In order to verify the validity of the design and to demonstrate the performance of the fast scanning prior to use in the new treatment facility, a new scanning-irradiation system was developed and installed into the existing HIMAC physics-experiment course. The authors made strong efforts to develop (1) the fast scanning magnet and its power supply, (2) the high-speed control system, and (3) the beam monitoring. The performance of the system including 3D dose conformation was tested by using the carbon beam from the HIMAC accelerator. RESULTS: The performance of the fast scanning system was verified by beam tests. Precision of the scanned beam position was less than +/-0.5 mm. By cooperating with the planning software, the authors verified the homogeneity of the delivered field within +/-3% for the 3D delivery. This system took only 20 s to deliver the physical dose of 1 Gy to a spherical target having a diameter of 60 mm with eight rescans. In this test, the average of the spot-staying time was considerably reduced to 154 micros, while the minimum staying time was 30 micros. CONCLUSIONS: As a result of this study, the authors verified that the new scanning delivery system can produce an accurate 3D dose distribution for the target volume in combination with the planning software.

Spontaneous cervical epidural hematoma treated by the combination of surgical evacuation and steroid pulse therapy.

A 70-year-old man on antiplatelet therapy developed sudden severe back pain in his neck with numbness and weakness in his extremities. On admission, he presented with complete quadriplegia, hypoesthesia, and anuria. Magnetic resonance imaging (MRI) revealed cervical cord compression due to an epidural hematoma posterior to the spinal cord and intramedullary hyperintensity. Surgical evacuation was performed about 12 hours after the onset, but the recovery of neurological deficits was poor. After performing 2 additional administrations of steroid pulse therapy, the patient's motor dysfunction began to improve and spinal MRI showed a recovery as well. These observations suggest that steroid administration should be considered as a post-operative additional therapy for cases with severe neurological deficits even after surgery.

Natural history of lumbar disc hernia with radicular leg pain: Spontaneous MRI changes of the herniated mass and correlation with clinical outcome.

A prospective sequential MRI study was done to investigate the morphologic changes of the lumbar disc hernia (LDH). We also studied the relationship between the MRI changes and the type of LDH and the clinical outcome. MRI was performed every 3 months from the onset for a maximum of 24 months in 42 patients with radicular leg pain and symptoms definitely diagnosed as caused by LDH. The size of the herniated mass was determined by the ratio of the anteroposterior diameter of the spinal canal to the maximum diameter of the LDH mass on T2-weighted axial images. The clinical outcome was evaluated as excellent, good, or poor depending on leg pain and physical findings. The JOA (Japanese Orthopaedic Association) score for LDH was also used to assess the outcome. Thirty-seven (88%) of the 42 patients showed >50% reduction of the hernia on MRI 3-12 months after onset, and the morphologic changes of the herniated mass were well correlated with the clinical outcome.