Needle trajectories

Fig. 4.21 Needle trajectory and angle with respect to the deltopectoral groove, pecto-ralis major, lateral border of the cephalic head of the pectoralis major muscle, and the chest wall. (From Belott PH. Blind axillar venous access. Pacing Clin Electrophysiol 1999 22(7) 1085-1089, with permission.)...

FIGURE 6 Planning and execution of MRI-guided prostate brachytherapy. Left three-dimensional model of the prostate, tumor, rectum, bladder, and seminal vesicles. The pelvic anatomy was segmented based on MR images. Middle the planning of the procedure. The peripheral zone and central zone of the prostate are depicted on a cross-sectional MRI slice acquired with an endorectal coil. The dashed lines represent individual needle trajectories. Right display of dose distribution on two-dimensional MRI of the prostate. 

The nano-electrospray (nanoES) source is essentially a miniaturized version of the ES source. This technique allows very small amounts of sample to be ionized efficiently at nanoliters per minute flow rates and it involves loading sample volumes of 1-2 pi into a gold-coated capillary needle, which is introduced to the ion source. Alternatively for on-line nanoLC-MS experiments the end of the nanoLC column serves as the nanospray needle. The nanoES source disperses the liquid analyte entirely by electrostatic means [27] and does not require assistance such as solvent pumps or nebulizing gas. This improves sample desolvation and ionization and sample loading can be made to last 30 minutes or more. Also, the creation of nanodroplets means a high surface area to volume ratio allowing the efficient use of the sample without losses. Additionally, the introduction of the Z-spray ion source on some instruments has enabled an increase in sensitivity. In a Z-spray ion source, the analyte ions follow a Z-shaped trajectory between the inlet tube to the final skimmer which differs from the linear trajectory of a conventional inlet. This allows ions to be diverted from neutral molecules such as solvents and buffers, resulting in enhanced sensitivity. 

The shape of a needle twins, i.e. the trajectory of the wall position y(x), is determined by the minimum of the total energy... 

The following solutions were found by Salje and Ishibashi (1996) for the coordination system shown in Figure 4. For case 1, bending dominated needles without lattice relaxation, the wall trajectory is close to a parabolic shape... 

This trajectory is also universal. For case 3, anisotropy dominated needles with elastic lattice relaxation or superposition of anisotropy energy and bending energy, we expect an exponential trajectory... 

Needle twin walls with exponential trajectories were observed in many ferroelastic materials such as Pb3(P04)2 and KSCN and for twin walls in BaTiOs. Typical length scales, X, are 85 pm (KSCN), 55 nm to 3pm [Pb3(P04)2] and 270 nm (BaTiOs). Furthermore, although the parabolic and linear cases show a correlation between the tip angle and needle width, this is less apparent for the exponential needles. The tip angle for... 

It can be observed that the presser-foot describes different trajectories depending on sewing speed. At the higher speed, when the feed-dog lowers below the throat plate (approximately between angles 250° and 300° of the stitch cycle), the presser-foot bounces up again and eventually loses contact with the fabric during needle penetration. 

Interventional procedures can be affected by patient motion or organ movement due to respiration (Xu et al. 2005). Thus, target movement must be recognized and accurately tracked, in addition to the constant calculation of the actual trajectory of a needle guide, based on the internal sensor systems of the robot. 

Needle compatibility and visualisation are both easy on CT. Volumetric acquisitions and multi-planar reformats aid appreciation of the needle position relative to the whole tumour volume in 3D (Antoch et al. 2002). This is particularly valuable for steep oblique, long trajectory needle placement (Fig. 22.1). CT will also show each of the multiple tines/prongs of the expandable electrodes, which can be difficult on US, i.e. there have been reports of a tine being advanced inadvertently into small bowel and this misplacement was not appreciated... 

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