Jacky Luiten

88 | Chapter 6 margin over a distance of 4 mm or less. Extensively involved margins include those in which tumor involvement of the inked margins extends beyond 4 mm. According to the Dutch guidelines, patients with focally involved resection margins are recommended to undergo either additional boost radiotherapy or additional surgical treatment. Additional surgical treatment is always recommended for patients with extensively involved resection margins. The median volume of the excised specimen was compared and calculated from an ellipsoid formula using the three dimensions measured by the pathologist: 4/3 π (0.5 length × 0.5 width × 0.5 height). 6 , 11 Guidewire and iodine ‐ 125 seed placement and detection The WGL technique involved a radiologist placing a hook wire under stereotactic or ultrasound guidance immediately preceding surgery, or the day before. In the latter situation, the hook wire, which was placed in the center of the lesion or as near to this as possible, was taped to the skin of the breast to prevent dislocation. For I ‐ 125 GL, a titanium seed containing 7MBq iodine ‐ 125 (BrachySource ® ; Bard, Covington, Georgia, USA) was injected into or near the tumor, as described previously. 8 , 9 Iodine ‐ 125 is a 27 ‐ keV source of γ radiation with a half ‐ life of 60 days. The cylindrical seed (length 4.5 mm, diameter 0.8 mm) was inserted into the lesion under ultrasound or stereotactic guidance using an 18G needle. The tip was sealed with sterile bone wax to prevent the seed being lost before insertion into the breast. If judged necessary, for instance in women with widespread segmental disease, the lesion was marked by two or three iodine seeds placed at the borders of the microcalcifications. After seed implantation, confirming mammography was carried out. Before incision and during the excision, a hand ‐ held γ‐ probe (Eurorad, Eckbolsheim, France) was used to determine the location of the iodine ‐ 125 seed in three dimensions. The seed implantation was done under direct responsibility of the Nuclear Medicine Department and according to the hospital’s license for the application of radiation in medical procedures under Dutch law. 12 Statistical analysis Continuous data are presented as mean (SD) or median (range), and were compared using Mann–Whitney U ‐ test. Proportional differences between I ‐ 125 GL and WGL groups were analyzed by chi ‐ square test. p< 0.050 was considered statistically significant. SPSS ® version 21.0 was used for statistical analysis (IBM, Armonk, New York, USA).