CT-fluoroscopy guided interstitial brachytherapy with image-based treatment planning for unresectable locally recurrent rectal carcinoma

PURPOSE: The aim of the study is to develop high-dose-rate (HDR) conformal interstitial brachytherapy by means of combined CT-fluoroscopy guidance with CT-based treatment planning for locally recurrent rectal carcinoma. METHODS AND MATERIALS: Brachytherapy needle insertion was guided with a helical CT scanner providing continuous fluoroscopy reconstruction. A video monitor placed adjacent to the CT gantry simultaneously allowed the operator to see the process of needle insertion. Final CT images were transferred by an online system to the treatment-planning computer, which reconstructed the implant needles and organ contours. The doses in planning target volume were normalized and geometrically optimized. The patients received a brachytherapy dose at 5 Gy twice daily with a hypofractionated accelerated schedule at a total dose of 30-50 Gy with or without external radiation therapy. Eighteen patients were treated with this procedure. RESULTS: Ten to thirty-six needles (average, 17.3) were successfully placed to the planning target volume in each patient. The average time for CT fluoroscopy was 357 seconds for each procedure. No accident was seen at needle insertion, but 2 patients developed incomplete peroneal nerve palsy after needle removal, but gradually recovered. CT-based treatment planning was faster and more accurate than projection reconstruction with conventional radiograms. Analysis of the dose volume histogram showed conformal dose distribution to the target, while avoiding normal structures. CONCLUSION: CT fluoroscopy guidance ensures safety and increases the accuracy of needle placement in brachytherapy. Conformal high-dose-rate (HDR) interstitial brachytherapy with CT-based treatment planning is a method worth considering for locally recurrent rectal cancer.     

Evaluation of HDR Interstitial Breast Implants Planned by Conventional and Optimized CT-Based Dosimetry Systems with Respect to Dose Homogeneity and Conformality

Background and Purpose: Recently, the use of brachytherapy for partial breast irradiation has increased significantly. The aim of this study was to make dosimetric comparisons between conventional (CONV) and CT-based optimized dosimetry systems applied to breast implants. Patients and Methods: 17 patients treated with high-dose-rate (HDR) interstitial brachytherapy were selected for the study. Two patients had two-plane and 15 three-plane implants. Treatment planning was based on conventional two isocentric radiographs and dose point optimization (CONV). For each patient postimplant CT scans were taken, and the target volume (lumpectomy cavity with 1 cm margin) was outlined in all axial slices. The treatment planning was repeated using CT images. The dose distributions were analyzed by dose-volume histograms. To quantify the dose distributions, volume (V90, V100, V150, V200) and dose (D90, D_min, mean central dose [MCD]) parameters, along with the dose nonuniformity ratio (DNR), dose homogeneity index (DHI), external volume index (EI) and conformal index (COIN) were used. For each implant, three more virtual treatment plans were created using the Paris dosimetry system (PDS), geometrically optimized system (GOS) and conformal system (CONF). Dose and volume parameters were calculated and compared. Results: The median number of catheters amounted to ten (range: 6 to 13) and the average volume of planning target volume to 63.4 cm³ (range: 17.7–122 cm³). The mean target coverage was 70%, 61%, 57% and 87%; the D90 72%, 64%, 60% and 94%; the DNR 0.35, 0.25, 0.25 and 0.55; the EI 0.62, 0.54, 0.08 and 0.15; the COIN 0.40, 0.34, 0.50 and 0.74 for the CONV, PDS, GOS and CONF systems, respectively. Conclusion: With CT-based optimized dose planning the target coverage can be significantly increased compared to the conventional dosimetry systems, but the target dose distribution will be more inhomogeneous. To improve the quality of brachytherapy implants, the image-based three-dimensional information should be used not only for dose plan evaluation, but also previously, for planning the geometry of the catheter positions and performing the insertions.     

CT-image-based conformal brachytherapy of breast cancer. The significance of semi-3-D and 3-D treatment planning.

PURPOSE: To compare the conventional 2-D, the simulator-guided semi-3-D and the recently developed CT-guided 3-D brachytherapy treatment planning in the interstitial radiotherapy of breast cancer. PATIENTS AND METHODS: In 103 patients with T1-2, N0-1 breast cancer the tumor bed was clipped during breast conserving surgery. Fifty-two of them received boost brachytherapy after 46 to 50 Gy teletherapy and 51 patients were treated with brachytherapy alone via flexible implant tubes. Single, double and triple plane implant was used in 6, 89 and 8 cases, respectively. The dose of boost brachytherapy and sole brachytherapy prescribed to dose reference points was 3 times 4.75 Gy and 7 times 5.2 Gy, respectively. The positions of dose reference points varied according to the level (2-D, semi-3-D and 3-D) of treatment planning performed. The treatment planning was based on the 3-D reconstruction of the surgical clips, implant tubes and skin points. In all cases the implantations were planned with a semi-3-D technique aided by simulator. In 10 cases a recently developed CT-guided 3-D planning system was used. The semi-3-D and 3-D treatment plans were compared to hypothetical 2-D plans using dose-volume histograms and dose non-uniformity ratios. The values of mean central dose, mean skin dose, minimal clip dose, proportion of underdosaged clips and mean target surface dose were evaluated. The accuracy of tumor bed localization and the conformity of planning target volume and treated volume were also analyzed in each technique. RESULTS: With the help of conformal semi-3-D and 3-D brachytherapy planning we could define reference dose points, active source positions and dwell times individually. This technique decreased the mean skin dose with 22.2% and reduced the possibility of geographical miss. We could achieve the best conformity between the planning target volume and the treated volume with the CT-image based 3-D treatment planning, at the cost of worse dose homogeneity. The mean treated volume was reduced by 25.1% with semi-3-D planning, however, it was increased by 16.2% with 3-D planning, compared to the 2-D planning. CONCLUSION: The application of clips into the tumor bed and the conformal (semi-3-D and 3-D) planning help to avoid geographical miss. CT is suitable for 3-D brachytherapy planning. Better local control with less side effects might be achieved with these new techniques. Conformal 3-D brachytherapy calls for new treatment planning concepts, taking the irregular 3-D shape of the target volume into account. The routine clinical application of image-based 3-D brachytherapy is a real aim in the very close future.     

Palliative Interstitial HDR Brachytherapy for Recurrent Rectal Cancer

PURPOSE: To report the methods and clinical results of CT-based interstitial high-dose-rate (HDR) brachytherapy procedures for the palliative treatment of recurrent rectal cancer. PATIENTS AND METHODS: A total of 44 brachytherapy implants were performed in 38 patients. CT-guided catheter implants were performed in 34 patients under local anesthesia and sedation, and four patients were implanted intraoperatively. Of 40 CT-guided implants, 20 were done using metallic needles introduced via the sacrum and 20 were transperineal implants of plastic tubes in the presacral region. Postimplant CT scans were used for three-dimensional (3-D) conformal brachytherapy planning. Patients implanted with metallic needles were given a single fraction of 10-15 Gy using HDR (192)Ir, and those who received transperineal implants of plastic catheters were given fractionated brachytherapy, 5 Gy twice daily to a total dose of 30-40 Gy. The median tumor volume was 225 cm(3) with a range of 41-2,103 cm(3). RESULTS: After a median follow-up of 23.4 months, a total of 13/38 patients were alive. The median postbrachytherapy survival was 15 months with 18 of the 25 deaths due to distant metastases. Tumor response was as follows: 6/38 partial remission, 28/38 stable disease, and 4/38 local progression. A planning target volume (PTV) coverage > 85% was achieved in 42/44 implants. The treatment was well tolerated, and no acute complications were observed. One patient developed a fistula after 8 months. Pain relief was recorded in 34 patients (89.5%), and the median duration of this palliative effect was 5 months with a range of 1-13 months. CONCLUSIONS: Interstitial HDR brachytherapy is a valuable tool for the delivery of high doses and achieves effective palliation in recurrent rectal carcinoma.     

Ultrasonographic monitoring of high dose rate interstitial implant using template technique for oral tongue cancer

192Ir high dose rate (HDR) fractionated interstitial brachytherapy was performed on two patients with tongue cancer with the aid of real-time intraoral ultrasonographic (US) guidance and the template technique. Blind-ended catheters with metallic rods (Obturator, Nucletron, the Netherlands) were inserted into the tongue from the submandibular region. This US monitoring allows for detection of the accurate location of both tumor and catheters in real-time motion. After implantation, we reconfirmed the position of the catheters by CT examination. Intraoral US monitoring was thus found to be a useful procedure for accurate implantation of brachytherapy for tongue cancer.     

CT-Guided Interstitial HDR Brachytherapy for Recurrent Glioblastoma Multiforme

BACKGROUND AND PURPOSE: Recurrences of glioblastoma multiforme (GBM) within previously irradiated volumes pose a serious therapeutic challenge. This retrospective study evaluates the long-term tumor control of recurrent GBM treated with interstitial high-dose-rate brachytherapy (HDR-BRT). PATIENTS AND METHODS: Between 1995 and 2003, 84 patients were treated for recurrent cerebral GBM located within previously irradiated volumes. All patients had received adjuvant external radiotherapy following primary surgery, with a focal dose up to 60 Gy. The median recurrent tumor volume was 51 cm(3) (3-207 cm(3)), and the HDR-BRT consisted of an afterloading (192)Ir implant which delivered a median dose of 40 Gy (30-50 Gy). Catheter implantation was implemented using interactive computed tomography (CT) guidance under local anesthesia and sedoanalgesia. RESULTS: After a median follow-up of 61 months, 5/84 patients (6%) were alive. The median post-BRT survival was 37 weeks, and the median overall survival 78 weeks. Moderate to severe complications occurred in 5/84 cases (6%). CONCLUSION: For patients with recurrences of GBM within previously irradiated volumes, CT-guided interstitial HDR-BRT is a feasible treatment option that can play an important role in providing palliation.     

The use of CT-based 3-D anatomical modeling in the design of customized perineal templates for interstitial gynecologic implants.

A system for preplanning interstitial treatment of gynecologic malignancies with a CT-based 3-dimensional planning system is presented. The preplan produces a custom template design that optimizes catheter placement. The procedure begins with a CT scan with a vaginal cylinder and blank template in place. Contours of the anatomic structures of interest, cylinder, and template are entered into the system, and 3-D surfaces are generated. The first view evaluated is oriented in a "cylinder's-eye view," which shows the path of the catheters placed parallel to the cylinder. In most cases this path to the tumor is obstructed by the pubic bones and bladder. By rotating the view posteriorly, the catheters can travel under the symphysis and bladder to the tumor. Once the optimum angle for visualization of the tumor has been determined, an array of catheters is designed to optimize the dose to the tumor. This array includes the special distribution in the oblique plane as well as the depth of insertion for each catheter. The design is then used in drilling the appropriate guide holes in the template. Orthogonal film dosimetry as well as CT verification of source placement will be compared to the preplan distribution.     

CT-guided multi-catheter insertion technique for partial breast brachytherapy: reliable target coverage and dose homogeneity

PURPOSE: To evaluate the feasibility and dosimetric reliability of a CT-guided method of catheter insertion for accelerated partial breast brachytherapy (APBB). MATERIALS AND METHODS: From 1995 to 2002, 77 patients were treated with APBB using a multi-catheter low-dose-rate or high-dose-rate approach. Within that timeframe, 29 patients with early stage invasive breast cancer were treated with high-dose-rate partial breast brachytherapy and had CT scans of the brachytherapy implant available for analysis. Initially, catheter insertion was accomplished in the operating room at the time of lumpectomy using standard free-hand insertion techniques under fluoroscopic guidance and subsequent orthogonal film dosimetry. To improve the efficiency and quality of the technique, the procedure was moved to the departmental CT-simulation suite where the catheters were placed with CT guidance. Basic guidelines of needle insertion and implant construction were followed to assure appropriate intercatheter and interplanar spacing that allowed optimal dosimetric coverage of the target volume. Target volumes were delineated and a treatment plan generated using a 3D planning system (Varian Brachyvision). PTV 1 cm was defined as the lumpectomy cavity plus 1 cm and PTV 2 cm as the lumpectomy cavity plus 2 cm. Target coverage goals were set as delivery of 100% of the prescribed dose to >95% of PTV 1 cm and >90% of the dose to >90% of PTV 2 cm. Dose homogeneity index (DHI) was defined as (V150%-V100%/V100%) with a goal of achieving >0.75. Fifteen patients were treated using the initial method and 14 patients using the CT-guided technique. Targets were retrospectively entered in the initial group and dose volume histogram analysis completed on all patients. The ability of each technique to achieve the target coverage and homogeneity goals was compared. RESULTS: With the change from traditional techniques to a CT-guided technique, the percentage of patients satisfying all dosimetric goals increased from 42% to 93%. Mean dose coverage (defined as the percentage of PTV 2 cm receiving 90% of the prescribed dose) increased from 89% to 95% (p=0.007) and the mean DHI increased from 0.77 to 0.82 with the new technique (p < 0.005). CONCLUSIONS: Reproducible target coverage and dose homogeneity were achieved with CT-guided catheter insertion and 3D planning software. Catheters can be optimally placed with intraoperative CT evaluation and 3D planning software allows improved implant visualization resulting in optimized dosimetry. Improvements in target coverage and DHI may translate into optimized local control and improved cosmesis with a corresponding reduction in the risk of complications.     

CT-Guided Interstitial Brachytherapy of Primary and Secondary Lung Malignancies

BACKGROUND AND PURPOSE: CT-guided interstitial brachytherapy of primary lung malignancies and pulmonary metastases represents a novel interventional technique, combining conventional high-dose-rate (HDR) iridium-192 ((192)Ir) brachytherapy with modern CT guidance for applicator positioning and computer-aided 3-D radiation treatment planning. The purpose of this study was to assess safety and efficacy of this technique. PATIENTS AND METHODS: 30 patients with 83 primary or secondary lung malignancies were recruited in a prospective nonrandomized trial (Table 1). After catheter positioning under CT fluoroscopy, a spiral CT was acquired for treatment planning (Figure 1). All but two patients received a defined single dose (coverage > 99%) of at least 20 Gy from a (192)Ir source in HDR technique. RESULTS: Adverse effects were nausea (n = 3, 6%), minor (n = 6, 12%) and one major pneumothorax (2%). Post intervention, no changes of vital capacity and forced expiratory volume could be detected. The median follow-up period was 9 months (1-21 months) with a local tumor control of 91% at 12 months (Figure 2). CONCLUSION: CT-guided interstitial brachytherapy proved to be safe and effective for the treatment of primary and secondary lung malignancies.     

Image fusion of CT and MRI data enables improved target volume definition in 3D-brachytherapy treatment planning

PURPOSE: To integrate MRI into CT-based 3D-brachytherapy treatment planning using a software system for image registration and fusion. METHODS AND MATERIALS: Sixteen patients with recurrent head-and-neck cancer, vulvar cancer, liposarcoma, and cervical cancer were treated with interstitial (n=12) and endocavitary (n=4) brachytherapy. CT and MRI scans were performed after implantation and prior to treatment planning. Image registration to integrate the CT and MR information into a single geometric framework was performed using a software algorithm based on mutual information. Conventional 3D-brachytherapy planning based on CT-information alone was compared to brachytherapy planning based on fused CT and MRI data. The accuracy of the image fusion was measured using predefined corresponding landmarks in the CT and MRI data. RESULTS: The presented automated algorithm proved to be robust and reliable (mean registration error 1.8 mm, range 0.8-4.1 mm, SD 0.9 mm). Tumor visualization was difficult using CT alone in all cases. Brachytherapy treatment planning based on fused CT and MRI data enabled better definition of target volume and risk structures as compared to treatment planning based on CT alone. CONCLUSIONS: Image registration and fusion is feasible for afterloading brachytherapy treatment planning. Treatment planning based on fused CT and MRI data resulted in improved target volume and risk structure definition.     

CT-guided interstitial brachytherapy in the local treatment of extrahepatic, extrapulmonary secondary malignancies

The purpose was to evaluate the safety and efficacy of high-dose-rate (HDR) CT-guided interstitial brachytherapy in the treatment of extrahepatic, extrapulmonary, secondary malignancies. Nineteen patients were included in this prospective study. The median age was 66 years (49–77). Underlying primaries comprised colorectal carcinomas in six, renal cell carcinoma in three, pancreatic carcinoma in three, cervical cancer in two, endometrial cancer in two and NSCLC, breast cancer and sarcoma in one patient each. All patients had undergone extensive pretreatments. CT-guided HDR brachytherapy employed a ¹⁹²Iridium source. Dose planning for brachytherapy was performed using 3D CT data acquired after CT-guided percutaneous applicator positioning. MRI follow-up was performed 6 weeks and every 3 months post intervention. Primary endpoints were complications, local tumor control and progression-free survival. The median tumor diameter was 6 cm (2–15 cm). Tumor locations included the hepatoduodenal ligament, mesentery, adrenal gland, mesogastrium and local recurrences after rectal or pancreatic cancer. The minimal median dose in the target volume was 11 Gy (4–18 Gy). Minor complications comprised pain and fever (n=6, 32%). Major complications included one hospital death of unknown causes (n=1; 5%). Median follow-up was 7 months (1–16). Four patients (21%) died during the follow-up period. Local tumor control was 76.5% after 6 months and progression-free survival 47% after 6 months. Minimally invasive CT-guided HDR brachytherapy is safe and effective in the palliative treatment of extrahepatic, extrapulmonary secondary malignancies.     

CT导向下125I粒子组织间植入治疗非小细胞肺癌

目的探讨CT引导下经皮穿刺植入^125I粒子近距离内照射治疗晚期非小细胞肺癌（NSCLC）的方法、疗效及并发症的处理。方法选择21例术前活检证实为NSCLC的患者,根据治疗计划系统（TPS）计算布源,于CT引导下经皮穿刺植入^125I粒子。粒子活度0．5～0．8mCi,间隔1．0～1．5cm多层面植入肿瘤内。术后即刻CT扫描验证,2～6个月复查CT观察粒子在瘤体内的分布、疗效及有无并发症,随访12个月。结果随诊CT复查,21例患者中完全缓解7例;部分缓解12例;稳定（无变化）2例。1年生存率90．5％（19／21）。并发症包括术中气胸6例,咳血2例。未见严重并发疗和治疗相关的放射损伤。结论CT导向下^125I粒了植入治疗NSCLC安全、有效,近期疗效肯定。     

CT-gesteuerte Brachytherapie

PURPOSE: To assess safety and efficacy of CT-guided brachytherapy of liver malignancies. PATIENTS AND METHODS: 21 patients with 21 liver malignancies (19 metastases, two primary liver tumors) were treated with interstitial CT-guided brachytherapy applying a (192)Ir source. In all patients, the use of image-guided thermal tumor ablation such as by radiofrequency or laser-induced thermotherapy (LITT) was impeded either by tumor size > or = 5 cm in seven, adjacent portal or hepatic vein in ten, or adjacent bile duct bifurcation in four patients. Dosimetry was performed using three-dimensional CT data sets acquired after CT-guided positioning of the brachytherapy catheters. RESULTS: The mean tumor diameter was 4.6 cm (2.5-11 cm). The mean minimal tumor dose inside the tumor margin amounted to 17 Gy (12-20 Gy). The proportion of the liver parenchyma exposed to > 5 Gy was 18% (5-39%) of total liver parenchyma minus tumor volume. Nausea and vomiting were observed in six patients after brachytherapy (28%). One patient demonstrated obstructive jaundice due to tumor edema after irradiation of a metastasis adjacent to the bile duct bifurcation. We commonly encountered asymptomatic increases of liver enzymes. Local control rates after 6 and 12 months were 87% and 70%, respectively. CONCLUSION: CT-guided brachytherapy is safe and effective. This technique displays broader indications compared to image-guided thermal ablation by radiofrequency or LITT with respect to tumor size or localization.     

HDR interstitial perineal implant for locally advanced or recurrent uterine cervix cancer

PURPOSE: To evaluate whether high-dose-rate (HDR) interstitial perineal implants can effectively eradicate residual tumor or recurrent tumor in uterine cervix cancer after complete radiation treatment. MATERIALS AND METHODS: This method of treatment was commenced in January 2002, and four advanced stage and four uterine cervix cancer (UCC) recurrences were admitted for this study. All untreated stage II bulky mass and IIIB patients received 50 Gy external beam radiotherapy (EBR) to the whole pelvis prior to the interstitial perineal implant. No EBR was given to recurrent UCC. Brachytherapy was delivered using Martinez Universal Perineal Interstitial Template (MUPIT) and 192Ir HDR. This implant will only be done if residual disease on the parametria was bimanually palpable or was proven by CT scan or MRI. The dose of interstitial brachytherapy boost to the parametria was 17 to 30 Gy, and treatment days ranged from 42 to 64 days. Uterine recurrences were found on the uterine cervix and/or parametria. The dose delivered by this implant ranged from 6 to 16 Gy and encompassed either uterus or vaginal stump and both parametria. Total treatment days ranged from 1 to 2 days. RESULTS: This short-term study showed that almost all tumors were locally controlled when the study was closed (1 to 15 months). One distant metastasis was found. No significant morbidity has been identified until now. CONCLUSION: HDR 192Ir interstitial perineal implants were proven to be effective in eradicating tumor cells in advanced stage UCC and recurrent disease with no significant morbidity.     

First pointwise encoding time reduction with radial acquisition (PETRA) implementation for catheter detection in interstitial high-dose-rate (HDR) brachytherapy

PURPOSEA pointwise encoding time reduction with radial acquisition (PETRA) sequence was optimized to detect empty catheters in interstitial (HDR) brachytherapy with clinically acceptable spatial accuracy for the first time. Image quality and catheter detectability were assessed in phantoms, and the feasibility of PETRA's clinical implementation was assessed on a gynecological cancer patient.METHODS AND RESULTSEmpty catheters embedded in a gelatin phantom displayed positive signal on PETRA and more accurate cross-sections than on clinically employed T2-weighted sequences, differing by 0.4 mm on average from their nominal 2 mm diameter. PETRA presented minimal susceptibility differences and a symmetric metal artifact, contrary to the clinical sequences. The PETRA-CT catheter tip position differences assessed by a treatment planning system (TPS) were < 1 mm. PETRA also detected an interstitial template with empty catheters penetrating a poultry phantom and fused very well with CT. Interstitial catheter positional difference between PETRA and CT images was < 1 mm on average, increasing with distance from isocenter. All interstitial catheters and the employed interstitial template were detected on PETRA images of an endometrial adenocarcinoma patient. Empty needles were traceable using a TPS, with higher spatial resolution and more favorable contrast than on T2-weighted images used for contouring. A treatment plan could be produced by combining information from PETRA for catheter detection and from T2-weighted images for tumor and organs delineation.CONCLUSIONSPETRA detected successfully and accurately interstitial catheters in phantoms. Its first clinical implementation shows a potential for MR-only treatment planning in interstitial HDR brachytherapy.     

CT引导下125I放射性粒子组织间植入治疗纵隔转移性淋巴结

目的 探讨CT引导下经皮穿刺125I放射性粒子植入治疗纵隔转移性淋巴结的技术方法、安全性及临床价值.方法 应用125I放射性粒子组织间种植治疗纵隔淋巴结转移患者8例,所有患者采用前路进针途径穿刺,按照病灶与体表穿刺点的位置设定CT机架的角度,采用多方位重组技术及平头针芯捻压分离主动脉、上腔静脉间隙进针法植入125I放射性粒子.疗效评价采用术后治疗计划系统(TPS),验证放射性粒子种植后剂量分布,观察治疗后患者局部压迫症状(气短、咳嗽、吞咽困难等)的改善情况及粒子植入术后2个月靶淋巴结的局部反应,并记录并发症情况.结果 植入术后粒子覆盖率为(93.5 ±1.5)％.术后2个月复查,其中完全缓解(CR)3例,部分缓解(PR)4例,病灶稳定(SD)1例.5例气短、4例咳嗽和吞咽困难等局部压迫症状均有不同程度减轻,未出现头颈部及上肢水肿.术后无严重并发症发生;无大血管、气管、食管损伤,1例出现少量气胸.结论 CT引导下经皮穿刺组织间放射性粒子植入治疗纵隔4R区肿瘤转移性淋巴结,疗效肯定、安全可靠,为常规治疗局部压迫症状较严重的复杂部位淋巴结转移,提供了一种新的微创治疗方法.     

Physikalische Grundlagen und klinische Durchführung der interstitiellen Brachytherapie der Prostata mit Jod-125

BACKGROUND: Interstitial brachytherapy with I-125 seeds can be used for successful treatment of early stage prostate cancer. There is presented the technique of permanent transperineal implantation of I-125 seeds with intraoperative treatment planning which is suited for the treatment of prostate cancer up to the clinical stage of T2a. MATERIAL AND METHODS: Some weeks before the implantation of the seeds the prostate volume is determined using transrectal ultrasound (TRUS) so as to estimate the required number of I-125 seeds. At the outset of the treatment the prostate is stabilized by two perineally inserted needles. Subsequently there is carried out an ultrasound guided treatment planning that allows to optimize the distribution of the seeds within the prostate. In interstitial brachytherapy we use RAPID STRANDS((R)), i. e. the I-125 seeds are embedded in vicryl suture at distances of 1 cm. During implantation of the I-125 seeds the transversal placement of the applicator needles is controlled by TRUS and the cranio-caudal placement of the applicator needles is controlled using the fluoroscopic unit as well as TRUS. About 4 weeks after the implantation of the seeds there is carried out a postoperative computation of the dose distribution of the implant using CT imaging. RESULTS: The procedure possesses the advantage that ultrasound imaging, treatment planning and seed implantation are carried out with the prostate remaining in an unaltered position. During implantation the combined imaging of TRUS and fluoroscopy allows a safe placement of the seeds with in the prostate. CONCLUSION: The methods for the calculation of the actually attained dose distribution must still be optimized, because the postoperative examination of the individual results has so far been possible only with difficulties resulting from methodological inconveniences.     

Evaluation of an MR-only interstitial gynecologic brachytherapy workflow using MR-line marker for catheter reconstruction

PurposeMagnetic resonance imaging (MRI) offers excellent soft-tissue contrast enabling the contouring of targets and organs at risk (OARs) during gynecological interstitial brachytherapy procedure. Despite its benefit, one of the main challenges toward MRI-only workflows is that the implanted catheters are not reliably visualized on MR images. This study aims to evaluate the feasibility of MR-only workflow using an in-house MR line marker during interstitial gynecological high-dose-rate (HDR) brachytherapy.Methods and MaterialsTen patients diagnosed with locally advanced cervical cancer treated with HDR brachytherapy were included in this study. The hybrid CT/MR-treated plan was used as the study reference plan. Five users manually reconstructed the catheter's path on MR images (3D T1- and T2-weighted). Subsequently, the dwell positions from the users’ plans were superimposed on the reference plans to evaluate the dosimetric impact of the using MR-only for catheter reconstruction in comparison with hybrid CT/MR approach. Variability of dwell positions between users and reconstruction time was also evaluated.ResultsMore than 96.90% of catheter reconstruction variations were < 2 mm. No statistical differences were reported between MR-only and hybrid CT/MR in gross tumor volume D₉₈ and high-risk clinical target volume D₉₀, respectively. For the OARs (bladder, sigmoid, rectum, and bowel), no significant changes were observed in any dose metrics between MR-only and hybrid CT/MR. The average reconstruction time was 51 ± 10 minutes across all ten patients.ConclusionThe feasibility of MR-only workflow using MR line marker during interstitial gynecological HDR brachytherapy has been validated in this study. The results show that the MR-only workflow is equivalent to the conventional hybrid CT/MR approach in terms of gross tumor volume and high-risk clinical target volume coverage and respecting of OARs dose limits.     

Ultrasound-Guided Interstitial Brachytherapy in the Treatment of Advanced Vaginal Recurrences from Cervical and Endometrial Carcinoma

BACKGROUND: In advanced vaginal recurrences of cervical and endometrial carcinomas therapeutic options are rare because of preceding therapy. PATIENTS AND METHODS: 23 patients developing advanced vaginal recurrences of cervical and endometrial carcinomas were included. 15 patients started with external-beam therapy to the pelvis and eight patients after preceding radiotherapy underwent brachytherapy alone. All patients had ultrasound-guided implantation of transvaginal or transperineal interstitial needles for brachytherapy. Median prescribed total dose was 64 Gy. RESULTS: 18 patients (78%) achieved complete remission. Six patients are alive without tumor and one with tumor after a median follow-up of 64 months. 14 patients died of tumor and two of intercurrent disease. 5-year disease-specific survival and local control rate were 43% and 47%, respectively, in patients with complete remission. Univariate analysis found time to relapse > 2 years, initial diameter < or = 4 cm, initial volume < 15 cm(3), no extension to the pelvic side wall, volume before brachytherapy < 7.5 cm(3), brachytherapy coverage index > 0.8, and prescribed total dose > 64 Gy being positive predictors for local control and survival. CONCLUSION: The use of ultrasound guidance for placement of interstitial needles in template-based brachytherapy of advanced recurrent gynecologic malignancies is a feasible, safe, and cheap method with encouraging results. Today, ultrasound imaging can be also used to some extent for treatment planning which requires further development. Patient- and treatment-related prognostic factors can be defined.     

CT引导下125I粒子植入治疗晚期胰腺癌的临床疗效分析

目的 探讨CT引导下125I粒子组织间植入治疗晚期胰腺癌的疗效.方法 回顾性分析2006年6月至2008年6月14例无法手术切除的晚期胰腺癌患者,于术前采用治疗计划系统(TPS)重建胰腺肿瘤的三维立体图像,通过TPS计算出所需粒子数目和总活度,在CT引导下将125I粒子植入胰腺肿瘤体内.采用的粒子活度为每粒0.5 ～ ...