Tianming Wu

Image-guided radiation therapy for prostate cancer: A computed tomography–based assessment of fiducial marker migration between placement and 7 days

PURPOSE This study was conducted to determine whether clinically significant fiducial marker migration occurs immediately after prostatic implantation. METHODS AND MATERIALS One hundred patients with transperineal (n = 39) or transrectal (n = 61) placement of 3 gold fiducial markers underwent computed tomography scans on day 0 (after placement) and day 7 (at radiation planning). Each marker was marked as a point of interest in a treatment planning system. An automated point-based algorithm was then used to coregister the day 0 and day 7 images by matching the markers through rigid translations and rotations. The mean distance between fiducial pairs (d¯) was recorded to assess the degree of seed migration. Prostate contours were delineated, and the day 0 prostate volumes were uniformly expanded by 1, 3, and 5 mm. The percentage of the day 7 prostate volume covered by each day 0 prostate with expansion was calculated to assess whether prostate contours, if performed on day 0, would adequately cover the prostate on day 7. RESULTS The average d¯ for all patients was 0.78 ± 0.45 mm; only 1 patient had d¯ > 2 mm. Placement technique, hormonal therapy, prostate size, and marker distance from the capsule were not associated with d¯ (P > .05). The mean percentages of day 7 prostate volumes covered by the day 0 prostate plus 1, 3, and 5 mm were 98.3%, 99.8%, and 100%, respectively. With an expansion of 3 mm, 98% of men had >95% of day 0 volume covered; with an expansion of 5 mm, 100% of men had 100% of the day 0 volume covered. CONCLUSIONS There is minimal change in the relative positions of fiducial markers (average d¯ < 1.0 mm) 1 week after placement. A 1- to 3-mm expansion would account for the variation in seed position for the vast majority of cases. These results suggest that planning could be performed on the day of implantation without adverse consequence.

Unresectable Hepatocellular Carcinoma Due to Portal Venous Thrombosis: Focal Stereotactic Body Radiation Therapy Can Promote Resectability

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality in the world [1]. Surgical resection and transplantation are the only chances for cure, but only in the patients without macrovascular invasion. As many as 44 % of all HCC cases are complicated by portal vein thrombosis (PVT), which is associated with a median survival of approximately 3 months and considered a contraindication to surgery [2–4]. Furthermore, transcatheter arterial chemoembolization (TACE) is usually contraindicated in patients with PVT, due to an increased risk of hepatic insufficiency and death [5]. Studies of local irradiation of PVT by conventional or 3D conformal techniques, often combined with TACE, have demonstrated response rates of 25–58 % [6–8]. Stereotactic body radiation therapy (SBRT) refers to a highly specialized technique to deliver large doses of radiation to precise tumor volumes, typically in five or fewer fractions. SBRT treatment involves advanced methods of pretreatment imaging and immobilization (or, when respiratory motion may influence the position of the target area, respiratory gating) to offer a high degree of treatment accuracy and reproducibility. Modern SBRT techniques have demonstrated safety and efficacy in the treatment of primary and metastatic liver tumors [9–11], and early reports indicate a rate of disease control which compares well with surgical resection [9]. However, few studies have evaluated SBRT in the treatment of PVT. This report details our experience with two patients who achieved regression of HCC-related PVT after treatment with SBRT and subsequently became candidates for surgical resection.