Mike C. Kirby

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A simple, low-cost, multipurpose phantom has been designed for use with electronic portal imaging devices (EPIDS). Making use of the high spatial resolution of an EPID, together with the built in software tools for measuring distances, it is possible to verify x-ray/light field size and congruence, at any gantry angle, for fields up to 200 mm x 200 mm.(More)
The organization of collagen in the supraspinous, interspinous, and longitudinal ligaments, as well as the ligamenta flava, in lumbar spines from human cadavers has been investigated by polarized light microscopy, scanning electron microscopy, and x-ray diffraction. These experiments were performed on ligaments in situ, with their bony attachments(More)
Verification of geometric accuracy at the time of treatment delivery has always been a necessary part of the radiotherapy process. Since the introduction of conformal and intensity-modulated radiotherapy, the consequences of patient positioning errors are more serious. Portal imaging has played a large part in fulfilling the need for improved geometric(More)
Stress-strain curves were recorded from anterior and posterior longitudinal ligaments and ligamenta flava dissected from pig lumbar spines. Ligaments were examined during extension by light microscopy, to observe crimp structure, and by X-ray diffraction, to determine collagen fibril orientations. Scanning electron microscopy (SEM) was used to examine(More)
PURPOSE To determine ways in which electronic portal imaging devices (EPIDs) could be used to (a) measure exit doses for external beam radiotherapy and (b) perform quality control checks on linear accelerators. METHODS AND MATERIALS When imaging, our fluoroscopic EPID adjusts the gain, offset, and frame acquisition time of the charge coupled device (CCD)(More)
A vital role in the quality control of radiotherapy is the use of portal imaging for verifying field size, shape, orientation and patient set-up. Coincidence of treated volume and target volume is imperative. Electronic portal imaging devices are effective at providing this verification. However, these devices are versatile enough to be used in other ways(More)
High standards of treatment verification are necessary where complex new delivery techniques, such as intensity modulated radiation therapy using dynamic multileaf collimation, are being developed. This paper describes the use of a fluoroscopic electronic portal imaging device (EPID) to provide real-time qualitative verification of leaf position during(More)
Advances in external beam therapy technology have made routine, efficient conformal therapy a reality. With it comes the increasing need for online treatment verification, which is only achievable at present through the use of electronic portal imaging devices (EPIDs). For a large radiotherapy centre, the provision of one EPID per treatment machine proves(More)
The dosimetric characteristics of a production pilot multi-leaf collimator (Elekta Beam Modulator, Elekta Oncology Systems, Crawley, UK) having a 4 mm leaf width (at isocentre) have been investigated. Characteristics explored included leaf bank set-up, penumbra width (80-20%) as a function of leaf position, leaf positioning reproducibility, interleaf(More)
The paper presents a computationally efficient 3D-2D image registration algorithm for automatic pre-treatment validation in radiotherapy. The novel aspects of the algorithm include (a) a hybrid cost function based on partial digitally reconstructed radiographs (DRRs) generated along projected anatomical contours and a level set term for similarity(More)