Image Guided Prone Catheter Insertion with a Special Breast Template

The Scar Solution Natural Scar Removal

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In 1996, the lead breast imager at the Ochsner Clinic, Dr. Gunnar Cederbom, asked me if I had ever considered brachytherapy in the prone position on a stereotactic core needle breast biopsy table. He pointed out the major advantages of such an approach:

1. In the prone position the breast hangs by gravity, pulling the breast tissue away from the pectoralis major muscle, ribs, and pleura.

2. The built-in mammography equipment under the table could be used to image the breast, facilitating image-guided breast brachytherapy.

3. Prior to the procedure, under ultrasound guidance, a small amount (about 3-5 ml) of nonionic contrast such as Omnipaque along with 2 ml air can be injected directly into the lumpectomy cavity, highlighting the seroma as well as all its crevices and outpouchings.

4. Attaching a template to the breast and taking a mammographic image directly down the holes should allow reliable, reproducible coverage of the target volume.

5. Any margin around the lumpectomy cavity can be chosen (e.g. 1, 1.5, 2.0, 2.5 cm, etc.) and theoretically one could have broader coverage on one side of the cavity, where the margin is perhaps tighter, and a smaller margin on the other side where the surgical margin is generous.

6. The procedure can be performed totally under local anesthesia with analgesia.

7. The resultant catheter distribution is a volume implant, rather than one or two planes, allowing much more flexibility for dosimetry and coverage of odd cavity shapes.

8. Assuming the template is attached in the same way, a radiation oncologist in a different state, or even a resident in training, would perform exactly the same implant as a very experienced brachytherapist would do.

A typical procedure would go as follows. The patient or a nurse applies topical lidocaine cream (EMLA) to the involved breast 1 to 2 hours before the start time. One hour before start time, the patient takes 5/325 mg Percocet and 5 mg Valium. The patient is taken to the ultrasound suite, where the seroma is identified. An ultrasound-compatible needle is inserted at least 2 cm away from the seroma, to avoid leakage of contrast agent later, after a small amount of local anesthetic has been injected to raise a skin wheal and along the planned path of the needle. The needle is positioned in the middle of the seroma, and approximately 80% of the seroma fluid is aspirated into a syringe. This decreases the target volume. Then 3 ml nonionic contrast agent and 2 ml air are injected directly into the cavity. The needle is withdrawn. The patient is taken to the stereotactic core biopsy suite in the Radiology Department, the surgeon's office, or your department, wherever the device is located. The table and underlying mammography equipment are draped in sterile fashion. The patient's breast is prepped with povidone-iodine or a similar solution. The patient is asked to lower her breast through the hole in the table, so that the nipple is centered and the breast hangs by gravity underneath the table (Fig. 9.11). The radiation oncologist or surgeon then palpates the seroma and faces the lumpectomy scar (Fig. 9.12). The template is positioned on the breast so that the surgical scar is between the two plates and visible to the physician (Fig. 9.13). The surgical scar should not be up against one of the plates because the catheters need to be parallel to the skin under the lumpectomy scar, not perpendicular, for dosimetry reasons. For smaller breasts, tincture of benzoin or an equivalent may be applied to the skin before the template is attached to prevent slippage. Usually, the upper edge of the template is placed tightly up against the chest wall so adequate deep coverage is provided. A mammographic image is taken with the line of the X-rays aligned along the holes in the template (Fig. 9.14). Since the mammography unit below the table is rotatable, the correct angle can be chosen so that front and back holes of coordinate C12, for example, are superimposed on the image (Fig. 9.15). The breast/template image obtained is remarkable, because the seroma is clearly seen with air/contrast and the template coordinates covering the target volume are easily identified (Figs. 9.16 and 9.17). Half-strength buffered local anesthetic is injected just under the skin surface to raise a skin wheal, and more dilute tumescent local anesthetic with epinephrine is injected directly down the planned holes of insertion for a relatively painless and bloodless procedure (Fig. 9.18). Since moderate compression is applied by the template, the cavity is somewhat spread out and elongated, causing the use of many more catheters than is usually seen with the old-style one- or two-plane implants. An average of 20 catheters are inserted with this procedure. After the needles

Hanging Breast Pics

Fig. 9.11 Patient lowering herself onto the ster-ilely-draped stereotactic core biopsy table with her prepped breast hanging by gravity

Fig. 9.12 Underneath the table, the breast separates from the chest wall, lungs, and pleura. The physician faces the lumpectomy scar in preparation for attaching the template

Mammography Positioning

Fig. 9.14 Overview of prone patient positioning and the underlying rotatable mammography equipment with drapes removed for clarity

Fig. 9.13 The template is attached with the scar facing outward and the base of the template usually up against the ribs

Fig. 9.14 Overview of prone patient positioning and the underlying rotatable mammography equipment with drapes removed for clarity

Fig. 9.15 Mammographic image with the front Fig. 9.16 The radiation oncologist or surgeon re-

and back template holes approximately aligned. views the films, noting the relation between the

Note the air-contrast level in the lumpectomy cav- contrast and the lumpectomy scar marked by a wire, ity. The target volume is delineated, and some of and plans the implant the proposed coordinates are marked by an X

Fig. 9.15 Mammographic image with the front Fig. 9.16 The radiation oncologist or surgeon re-

and back template holes approximately aligned. views the films, noting the relation between the

Note the air-contrast level in the lumpectomy cav- contrast and the lumpectomy scar marked by a wire, ity. The target volume is delineated, and some of and plans the implant the proposed coordinates are marked by an X

Fig. 9.17 Illustration with the contrast-enhanced lumpectomy cavity in magenta, and the target volume in gray, facilitating image-guided brachy-therapy

25 Ga Needle

25 Ga Needle

Fig. 9.18 Tumescent local anesthesia is injected directly down the path of all planned needles before any needles are placed, making sure that a skin wheal is raised on both sides

Fig. 9.19 A breast CT is obtained the day after the procedure for 3D treatment planning. Note how the deep plane can be positioned across the pectoralis fascia with this prone technique. The even distribution of catheters around the cavity promotes excellent dosimetry with a high dose homogeneity index are in place, the template is disassembled and removed from the breast. Plastic Comfort catheters are then inserted inside each needle and pulled until the needle is out and a distal hemispherical button touches the skin at the entry position. A button is placed at the other end of each catheter and attached to the catheter, securing it in place, and the catheter is trimmed to the button. Bacitracin ointment is applied at each entry/exit site, and a Surgibra is used to hold ABD pads in place over the implant so no tape is necessary. A treatment-planning CT scan is obtained of the involved breast on the next day, after any swelling has subsided (Fig. 9.19). The contrast-enhanced lumpectomy cavity is contoured on each CT slice, and this volume is expanded the desired amount (usually 1.5-2 cm) on the computer as the planning target volume (PTV). Within each catheter, dwell times are selected at 0.5-cm intervals so that the PTV is covered by the prescription isodose line, with an acceptable (>0.75) dose homogeneity index. Treatment systems have dose optimization algorithms that facilitate PTV coverage, but it is important to make sure that none of the 150% isodose curves connect between one catheter and an adjacent one.

Since the catheter insertion with this technique is done in the prone position, and the CT-planning and HDR treatments are done in the supine position, there will be some change in the geometry of the catheters as the patient changes position. This is acceptable, because the treatment is done in the same position as the CT-planning. A practical advantage of treating the patient in the supine position is that the deep row of catheters usually drapes across the pectoralis major muscle and chest wall, insuring excellent deep coverage (Fig. 9.19) that is usually the most problematic issue with freehand techniques. Also, pneumothorax occurs in a small percentage of freehand procedures, either from the thin local anesthetic needle or the brachytherapy needle itself, but in the prone position with a parallel plate template system, pneumothorax should never be seen as a complication.

Figure 9.20 demonstrates the typical cosmetic outcome 6 months after brachytherapy with this technique. Note the absence of radiation skin changes, and pock marks that will continue to become fainter and more subtle over time. This is a soft breast.

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