Partial body irradiation of small laboratory animals with an industrial X-ray tube

AIMS: Dedicated precise small laboratory animal irradiation sources are needed for basic cancer research and to meet this need expensive high precision radiation devices have been developed. To avoid such expenses a cost efficient way is presented to construct a device for partial body irradiation of small laboratory animals by adding specific components to an industrial X-ray tube.

METHODS AND MATERIALS: A custom made radiation field tube was added to an industrial 200kV X-ray tube. A light field display as well as a monitor ionization chamber were implemented. The field size can rapidly be changed by individual inserts of MCP96 that are used for secondary collimation of the beam. Depth dose curves and cross sectional profiles were determined with the use of a custom made water phantom. More components like positioning lasers, a custom made treatment couch, and a commercial isoflurane anesthesia unit were added to complete the system.

RESULTS: With the accessories described secondary small field sizes down to 10 by 10 mm(2) (secondary collimator size) could be achieved. The dosimetry of the beam was constructed like those for conventional stereotactical clinical linear accelerators. The water phantom created showed an accuracy of 1mm and was well suited for all measurements. With the anesthesia unit attached to the custom made treatment couch the system is ideal for the radiation treatment of small laboratory animals like mice.

CONCLUSION: It was feasible to shrink the field size of an industrial X-ray tube from whole animal irradiation to precise partial body irradiation of small laboratory animals. Even smaller secondary collimator sizes than 10 by 10 mm(2) are feasible with adequate secondary collimator inserts. Our custom made water phantom was well suited for the basic dosimetry of the X-ray tube.