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Purpose: As the practice of using high-energy photon beams to create therapeutic radiation fields of subcentimeter dimensions ͑as in intensity-modulated radiotherapy or stereotactic radiosurgery͒ grows, so too does the need for accurate verification of beam output at these small fields in which standard practices of dose verification break down. This study investigates small-field output factors measured using a small plastic scintillation detector ͑PSD͒, as well as a 0.01 cm 3 ionization chamber. Specifically, output factors were measured with both detectors using small fields that were defined by either the X-Y collimator jaws or the multileaf collimator ͑MLC͒. Methods: A PSD of 0.5 mm diameter and 2 mm length was irradiated with 6 and 18 MV linac beams. The PSD was positioned vertically at a source-to-axis distance of 100 cm, at 10 cm depth in a water phantom, and irradiated with fields ranging in size from 0.5ϫ 0.5 to 10ϫ 10 cm 2 . The field sizes were defined either by the collimator jaws alone or by a MLC alone. The MLC fields were constructed in two ways: with the closed leaves ͑i.e., those leaves that were not opened to define the square field͒ meeting at either the field center line or at a 4 cm offset from the center line. Scintillation light was recorded using a CCD camera and an estimation of error in the medianfiltered signals was made using the bootstrapping technique. Measurements were made using a CC01 ionization chamber under conditions identical to those used for the PSD. Results: Output factors measured by the PSD showed close agreement with those measured using the ionization chamber for field sizes of 2.0ϫ 2.0 cm 2 and above. At smaller field sizes, the PSD obtained output factors as much as 15% higher than those found using the ionization chamber by 0.6ϫ 0.6 cm 2 jaw-defined fields. Output factors measured with no offset of the closed MLC leaves were as much as 20% higher than those measured using a 4 cm leaf offset. Conclusions:The authors' results suggest that PSDs provide a useful and possibly superior alternative to existing dosimetry systems for small fields, as they are inherently less susceptible to volume-averaging and perturbation effects than larger, air-filled ionization chambers. Therefore, PSDs may provide more accurate small-field output factor determination, regardless of the collimation mechanism.

Internal fixation for fractures of the humeral capitellum is a technically challenging procedure. Controversy exists regarding the optimal surgical approach and fixation technique. The benefit of stable fixation of the capitellum fragment is early mobilization. Our preferred technique involves anatomic reduction of the capitellar fragment and fixation with headless screws placed from anterior to posterior. When possible, the surgical exposure employed preserves the lateral ulnar collateral ligament (LUCL) and minimizes disruption of the soft tissues posterior to the capitellum.

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