Development of a variable energy RFQ for cluster acceleration
An RFQ (radio-frequency quadrupole) has been designed and built as a postaccelerator for the cluster accelerator facility at the IPN (Institute de Physique Nucleaire) Lyon, France. The four-rod RFQ resonator is designed for variable energy by means of a variable frequency of the resonator between 80 and 110 MHz. The properties of the RFQ for the typical cluster mass ranges of up to 50 u are discussed and the status of the project is reported.<<ETX>>
RFQ ion accelerators with variable energy
Abstract RFQs are low-energy rf accelerator structures which can efficiently transport and accelerate high-current ion beams. Whilst usually RFQs, like all rf accelerators, have a fixed velocity profile and output energy per amu, attempts have been made to vary the ion beam energy by changing the resonator frequency. The 4-rod λ/2-RFQ resonator developed in Frankfurt for heavy-ion acceleration is well suited for such an application. Results of the work on variable-energy VE-RFQs are presented and the status of the variable-energy cluster accelerator project is discussed.
Direct orbital manometry in patients with thyroid-associated orbitopathy.
PURPOSE
To determine orbital tissue tension and orbital compartment compliance in patients with and without thyroid-associated orbitopathy (TAO).


DESIGN
Prospective case series.


PARTICIPANTS
Orbits of patients with TAO (18 orbits) and control patients without TAO (35 orbits) were studied.


METHODS
An orbital manometer was designed to directly measure orbital tissue tension in patients undergoing ocular or orbital surgery.


MAIN OUTCOME MEASURES
Tissue tension was recorded before, during, and for 5 minutes after a 5-ml retrobulbar injection of anesthetic. Orbital compliance was calculated as change in volume divided by change in tissue tension.


RESULTS
Resting orbital tissue tension was 4.4 +/- 2.2 mmHg (mean +/- SD) in normal orbits and 9.7 +/- 4.8 mmHg in orbits of TAO patients (P = 0.0005) Following retrobulbar injection, orbital tissue tension rose to 12.0 +/- 3.6 mmHg (P = 0.0000000000000006 compared with baseline) in the control group and to 36.3 +/- 15.2 mmHg in the TAO group (P = 0.0000007 compared with baseline, and P = 0.000008 TAO group versus control group). Orbital compartment compliance was 0.80 +/- 0.50 ml/mmHg in the control group and 0.27 +/- 0.21 ml/mmHg in the TAO group (P = 0.00001). Resting orbital tissue tension in 8 TAO orbits with compressive optic neuropathy was 12.4 +/- 4.9 mmHg, and was 7.8 +/- 3.5 mmHg in 10 orbits of TAO patients without compressive optic neuropathy (P < 0.05). No adverse events occurred.


CONCLUSIONS
Retrobulbar injection causes consistent measurable changes in orbital tissue tension. Orbital manometry safely demonstrated higher orbital tissue tension and lower orbital compartment compliance in the orbits of TAO patients versus those of normal subjects. Resting orbital tissue tension was higher in the orbits of TAO patients with compressive optic neuropathy than in those orbits without. Compressive optic neuropathy may partially result from an orbital compartment syndrome in some patients with TAO. Directly assessing orbital dynamics in vivo may prove useful as an adjunct in the clinical evaluation of patients with TAO and other orbital disorders.