A New Infrared-Based Design for Measuring the Source to Skin Distance

Yalcin Isler, Alpman Manalp


Cancer is a major public health problem worldwide. There are many types of cancer therapy methods including the radiotherapy. In radiotherapy, positioning the patient to a consistent treatment location is significantly crucial to receive an effective dose, which closely affects the success of the therapy. The most commonly used parameter for ensuring the effective patient position is the source to skin distance (SSD). In this study, an infrared-based SSD measuring device is developed and its feasibility and accuracy are tested. The prototype of the infrared SSD measuring device (IRD) is composed of two major parts: a measuring distance sensor unit and a control unit. The microcontroller-based control unit displays the measurement in millimeters and transmits it to a computer via serial port. The SSD measurement experiments were conducted on a Siemens Primus Linear Accelerator with a full-sized male phantom. Thirty measurements were conducted at different gantry angles for anatomic locations in order to determine the mean values and standard deviations. This device was tuned by a conventional mechanical ruler with an accuracy of 0.7324 mm. The results revealed that the proposed device gives more consistent and accurate readouts with smaller variations in all body functions than other devices.


Patient setup; Positioning error; Source-to-skin distance; Linear accelerators

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DOI: http://dx.doi.org/10.7212%2Fzkufbd.v9i2.1448

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