Inverse treatment planning for spinal robotic radiosurgery: an international multi-institutional benchmark trial.

Stereotactic radiosurgery (SRS) is the accurate, conformal delivery of high-dose radiation to well-defined targets while minimizing normal structure doses via steep dose gradients. While inverse treatment planning (ITP) with computerized optimization algorithms are routine, many aspects of the planning process remain user-dependent. We performed an international, multi-institutional benchmark trial to study planning variability and to analyze preferable ITP practice for spinal robotic radiosurgery.

Abdominal organ motion measured using 4D CT.

Purpose: To measure respiration-induced abdominal organ motion using four-dimensional computed tomography (4D CT) scanning and to examine the organ paths.

Methods And Materials: During 4D CT scanning, consecutive CT images are acquired of the patient at each couch position. Simultaneously, the patient's respiratory pattern is recorded using an external marker block taped to the patient's abdomen.

Modeling the self-assembly of copolymer-nanoparticle mixtures confined between solid surfaces.

Using numerical calculations, we undertake the first morphological studies of mixtures of AB diblocks and nanoparticles that are confined between two hard walls. A complex interplay of entropic and enthalpic interactions drives the nonselective particles to localize at the hard walls and A/B interfaces, causing the mixture to spontaneously self-assemble into particle-decorated lamellae that are oriented perpendicular to the surfaces. The film reveals a periodic array of particle "nanowires" that are separated by the nanoscale polymer domains, yielding a vital material for nanodevice fabrication.