An image projecting system for irradiating a microfilm with light emitted from a light source and projecting an image recorded on the microfilm onto an image receptor such as a screen or a photosensitive drum, the image projecting system having a masking unit which is mounted in the body of the system removably. The masking unit contains a first masking portion which is for changing the range of the image advancing toward the image receptor through an optical path, in a first direction of the microfilm, and a second masking portion which is for changing the range of the image in a direction approximately perpendicular to the said first direction. These masking portions are disposed in close proximity to the microfilm. Thus, a desired range of the image recorded on the microfilm can be projected on the image receptor and the outer peripheral edge of the projected image is made sharp and clear by the above masking portions. Normal operation and other operations for maintenance can be done easily by removing the masking unit from the system body.
A hyperthermia treatment apparatus includes an annular radio frequency (RF) antenna array with bolus that is compatible with a magnetic resonance imaging (MRI) machine. Antenna elements polarized parallel to the axis of the cylinder are used for forming a Specific Absorption Ratio (SAR) map as well as for directing the energy to accomplish hyperthermia. The array may be dynamically controlled to focus energy at any specified region within the cylinder. The array is positioned inside an MRI machine and is tuned to the machine's hydrogen resonant frequency. For treatment planning, the array is employed to form an SAR map via RF current density imaging. Using this map, array phase, amplitude, and temporal weighting are optimized until the SAR maxima is congruent with the treatment volume. For treatment, RF radiation is applied to the subject to induce heating of the treatment volume using these optimal array parameters. Temperature is periodically determined via noninvasive MRI methods (i.e., diffusion imaging, T.sub.1 map, etc.) in order to obtain an image that includes isotherms from which the pattern of heating can be observed. Feedback is provided such that adjustment may be made to compensate for bioheat transfer.
