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.     

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.     

Fractionated Intraluminal HDR 192Ir Brachytherapy as Palliative Treatment in Patients with Endobronchial Metastases from Non-Bronchogenic Primaries

AIM: To evaluate the efficacy of iridium-192 high-dose rate (HDR) endobronchial brachytherapy for the palliation of symptoms caused by endobronchial metastases of non-bronchogenic primaries. PATIENTS AND METHOD: Between 1991 and 1998, eleven patients (female n = 3, male n = 8; age: median 66 years, range 44-81 years) underwent intraluminal HDR brachytherapy for histologically confirmed endobronchial metastases from non-pulmonary primary tumors of various sites like urogenital tract (n = 5), gastrointestinal tract (n = 3), ear/nose/throat (n = 2) and breast (n = 1). The median time between diagnosis of the primary non-bronchogenic tumor and histopathological diagnosis of the endobronchial metastases was 39 months, range 1-99 months. A total dose of 15-20 Gy was delivered in three to four fractions of 5-6 Gy once a week. No palliative chemotherapy was added. RESULTS: Median follow-up after palliative brachytherapy was 15 months (range 1.4-59 months). Objectively, complete endoscopic response was observed in three (27%) patients, and in five (46%) others partial opening of the initially obstructed airway was achieved. Treatment was judged unsuccessful in three (27%) patients. No patient showed up with local progression. At date of analysis five patients were alive with documented residual tumor (80%) or complete response (20%). Relief of symptoms occurred in the vast majority of patients (n = 8, 73%). CONCLUSION: HDR intraluminal brachytherapy palliates symptoms in patients suffering from endobronchial metastases of non-pulmonary primary tumors. The applied treatment is a safe, effective and well tolerated palliative procedure leading to an improved patient quality of life.     

瘤段切除结合内照射治疗恶性骨肿瘤临床分析

目的观察高剂量率骨内插植内照射治疗骨肿瘤的保肢效果。方法8例恶性骨肿瘤均在术中置管进行内照射,每次治疗10 Gy,2次/周,共6次,总剂量60 Gy。治疗后2周有5例行瘤段切除术。结果所有病人都能耐受治疗,瘤段切除标本见瘤段区均有广泛坏死、出血、死骨残存及组织退变,肿瘤的边缘3~6 Gy照射区发现有少量退变不明显的瘤细胞存在,生存1年和3年分别有7例和5例。结论高剂量率骨内插植内照射结合瘤段切除治疗骨肿瘤是可行的。     

CT-Guided Brachytherapy (CTGB) versus Interstitial Laser Ablation (ILT) of Colorectal Liver Metastases

PURPOSE: To compare local tumor control after percutaneous tumor ablation by interstitial laser therapy (ILT) or CT-guided brachytherapy (CTGB). PATIENTS AND METHODS: In a matched pair analysis including 18 patients with 36 liver metastases of colorectal primary, both ILT and CTGB were performed in different lesions. The following matching factors were considered: (i) tumor size < or = 5 cm, and (ii) execution of chemotherapy after tumor ablation. Primary endpoint was local tumor control. RESULTS: Treated lesions were identical in terms of tumor size and all matching criteria were fulfilled in all patients except for the performance of adjuvant chemotherapy. Median follow-up was 14 months (3-24 months) for both groups. Only five of 18 patients (28%) demonstrated local tumor progression after CTGB, whereas in ten of 18 patients (56%) tumor progression was found after ILT. Differences encountered were significant for all patients (p = 0.04), whereas in those who fulfilled all matching criteria (n = 14) the level of statistical significance was not reached (p = 0.23). CONCLUSION: CTGB demonstrated superior local tumor control compared to ILT in long-term follow-up.     

Evaluation of Scatter Contribution and Distance Error by Iterative Methods for Strength Determination of HDR 192Ir Brachytherapy Source

High-dose rate (HDR) ¹⁹²Ir brachytherapy sources are commonly used for management of malignancies by brachytherapy applications. Measurement of source strength at the hospital is an important dosimetry requirement. The use of 0.6-cm³ cylindrical ionization chamber is one of the methods of measuring the source strength at the hospitals because this chamber is readily available for beam calibration and dosimetry. While using the cylindrical chamber for this purpose, it is also required to determine the positioning error of the ionization chamber, with respect to the source, commonly called a distance error (c). The contribution of scatter radiation (M_s) from floor, walls, ceiling, and other materials available in the treatment room also need to be determined accurately so that appropriate correction can be applied while calculating the source strength from the meter reading. Iterative methods of Newton-Raphson and least-squares were used in this work to determine scatter contribution in the experimentally observed meter reading (pC/s) of a cylindrical ionization chamber. Monte Carlo simulation was also used to cross verify the results of the least-squares method. The experimentally observed, least-squares calculated and Monte Carlo estimated values of meter readings from HDR ¹⁹²Ir brachytherapy source were in good agreement. Considering procedural simplicity, the method of least-squares is recommended for use at the hospitals to estimate values of f (constant of proportionality), c, and M_s required to determine the strength of HDR ¹⁹²Ir brachytherapy sources.     

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.     

A novel rectal applicator for contact radiotherapy with HDR 192Ir sources

PurposeDose escalation to rectal tumors leads to higher complete response rates and may thereby enable omission of surgery. Important advantages of endoluminal boosting techniques include the possibility to apply a more selective/localized boost than using external beam radiotherapy. A novel brachytherapy (BT) rectal applicator with lateral shielding was designed to be used with a rectoscope for eye-guided positioning to deliver a dose distribution similar to the one of contact x-ray radiotherapy devices, using commonly available high-dose-rate ¹⁹²Ir BT sources.Methods and MaterialsA cylindrical multichannel BT applicator with lateral shielding was designed by Monte Carlo modeling, validated experimentally with film dosimetry and compared with results found in the literature for the Papillon 50 (P50) contact x-ray radiotherapy device regarding rectoscope dimensions, radiation beam shape, dose fall-off, and treatment time.ResultsThe multichannel applicator designed is able to deliver 30 Gy under 13 min with a 20350 U (5 Ci) source. The use of multiple channels and lateral shielding provide a uniform circular treatment surface with 22 mm in diameter. The resulting dose fall-off is slightly steeper (maximum difference of 5%) than the one generated by the P50 device with the 22 mm applicator.ConclusionsA novel multichannel rectal applicator for contact radiotherapy with high-dose-rate ¹⁹²Ir sources that can be integrated with commercially available treatment planning systems was designed to produce a dose distribution similar to the one obtained by the P50 device.     

Dosimetric study of Varian Universal Multi-Channel Cylinder System for High-Dose-Rate 192Ir Brachytherapy

PurposeRecently, the Varian multichannel vaginal cylinder (MCVC) set for high-dose-rate ¹⁹²Ir brachytherapy was commercially released. This MCVC was distinct from our existing MCVC in its peripheral channel layout and tip design. This investigation sought to assess the dosimetric impact of these changes.Methods and MaterialsThe dimensions of the virtual model for each applicator were compared against both physical and radiographic measurements. Volumetric dose distributions were generated in silico using a model-based dose calculation algorithm (MBDCA). To characterize the effects of the new peripheral channel layout on dose to adjacent areas (“dose-spill”), point doses were compared using two sets of applicator-based reference points: at surface or 5 mm radially from surface. To evaluate the dose-shaping capabilities, a dose distribution was generated for the new applicator and assessed against a representative dose distribution for a patient previously treated with existing equipment.ResultsBased on both physical and radiographic measurements, virtual models were representative of each applicator within ±1 mm. Commissioning of the MBDCA was benchmarked based on AAPM Working Group on Dose Calculation Algorithms in Brachytherapy. The layout of the new applicator reduced dose-spill to other reference points significantly, as much as a factor of 16.3, compared with the existing equipment. The rounded tip shape and curve of the peripheral channels in the new applicator produced more conformity to its HR-CTV than existing equipment.ConclusionsCompared with our existing equipment, the design changes in the new Varian MCVC set offered improved control of dose spill and better conformality to HR-CTV.     

Interstitial Brachytherapy with Ir-192 Low-Dose-Rate in the Treatment of Primary and Recurrent Cancer the Oral Cavity and Oropharynx

AIM: To evaluate the impact of postoperative interstitial brachytherapy with and without external radiotherapy in the treatment of primary and recurrent squamous cell carcinoma of the oral cavity and oropharynx. PATIENTS AND METHODS: Between 1985 and 1997, a total of 318 patients were treated by interstitial Ir-192 low-dose-rate brachytherapy as part of their primary (n = 236) or recurrent treatment (n = 82). There were 263 male (83%) and 55 (17%) female patients. The distribution of UICC (1997) stages was as follows: I (61 patients, 19%), II (71 patients, 22%), III (58 patients, 18%), IV (128 patients, 40%). The primary tumor site was located in the oral cavity in 201 patients (63%), in the oropharynx in 86 patients (27%), lower lip in 19 patients (6%) and other regions in twelve cases (4%). Treatment concepts did not vary over the time and were dictated by the initial tumor extension: a total of 175 patients (55%) received a combination of surgery, interstitial brachytherapy (23-25 Gy) and external radiotherapy (50-60 Gy), 60 patients (19%) surgery and interstitial brachytherapy (45-55 Gy) alone. Advanced disease not amenable to primary surgery was either treated by radiochemotherapy and interstitial brachytherapy in 39 patients (12%) or a combination of interstitial brachytherapy, external radiotherapy and interstitial hyperthermia in 44 patients (14%). RESULTS: Overall survival rates following primary and recurrent treatment were 50 +/- 4% and 29 +/- 5%, respectively, at 5 years (p < 0.0001). A significant impact on overall survival rate was noted for UICC stage: patients in stage I/II had survival rates of 64 +/- 5% and 57 +/- 10%, respectively, while patients in stage III/IV had survival rates of 39 +/- 5% and 15 +/- 5%, respectively, at 5 years (p < 0.0001). In addition, grading (p = 0.01) and hemoglobin levels (p = 0.05) had a significant influence on overall survival. Local tumor control rates for all patients were 74 +/- 3% and 57 +/- 7% at 5 years following primary and recurrent treatment (p = 0.01), respectively. The 145 patients treated for primary disease by a uniform concept of surgery, interstitial brachytherapy and external radiotherapy achieved excellent local control rates with 92 +/- 4% (stage I/II) and 65 +/- 6% (stage III/IV) at 5 years. Late treatment-related toxicity with soft tissue necrosis and/or osteonecrosis requiring mandibular resection was 7.5%. CONCLUSION: Local tumor excision followed by postoperative interstitial brachytherapy with and without external radiotherapy is associated with excellent locoregional control, a low risk of chronic sequelae and may therefore considered as a new approach avoiding mutilating radical surgery.