28 Primary and secondary liver malignancies

Primary and secondary liver malignancies

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 15/07/2022

Figure 4: An example of the set-up (left image) and material (right image) used for CT-guided catheter implantation using the Seldinger technique. Exemplar materials used for implant: 1) sterile swaps and compresses, 2) sterile draping material, 3) scalpel and hollow puncture needle, 4) numbered angiography sheaths, 5) brachytherapy catheters.

Figure 5: Schematic workflow of the catheter placement using the Seldinger technique (left) and image of the final implant (right). The blue brachytherapy catheter can be seen inside the green/white angiography sheath. The transfer tube of the afterloader (not included in the image) will be connected directly to the blue brachytherapy catheter.

8. TECHNIQUE

Although no relative movements between the target and the applicator are expected, the expected overall uncertainty should be considered when creating the PTV. The largest uncertainty in dose delivery is the potential change of patient anatomy and catheter location between simulation imaging and dose application [50]. Additional spatial uncertainties are caused by offsets of the afterloader dwell positions, uncertainties in image registration, image resolution, target volume andOAR delineation and catheter reconstruction. Such influences, in addition to dose calculation uncertainties (described below under “Treatment planning”) must be quantified or estimated to determine the PTVmargin (typically in the range of 1-3 mm). Since large PTV margins may increase the total PTV volume significantly, the choice for the PTVmargin should be carefully considered and frequently, no PTV margin is applied at all in clinical practice (CTV = PTV). In any case, the target volume should be fully containedwithin the liver. In addition, OAR such as liver, stomach, duodenum, colon, small intestine, kidneys and heart are delineated (see Figure 3).

Materials Amongst several different techniques to perform liver implants, the direct puncture method and the Seldinger technique are the ones most commonly used. The catheter-in-catheter Seldinger technique is frequently used by interventional radiologists [51]. Catheter placement via the Seldinger technique (usually under fluoroscopy-CT-guidance), requires sterile swabs and compresses, a scalpel, a hollow puncture needle, an angiography sheath, a stiff guide-wire, the brachytherapy catheters, suture material for suturing the sheath to the skin and sterile solution for preparing the procedural site. An example is given in figure 4. Hydrophilic coated sheaths allow an easy insertion and reduce pain for the patient during skin and liver capsule puncture. After the dose delivery, catheters are removed. Small pieces of gelatine foam are used to prevent bleeding. The gelatine foam is cut out, rolled and