Interstitial Implants Research Articles

Indices from dose-volume histograms as tools for optimized brachytherapy in interstitial implants for treatment of sarcomas

Indices from dose-volume histograms as tools for optimized brachytherapy in interstitial implants for treatment of sarcomas

Dose enhancement by various nanoparticles in prostate brachytherapy

The aim of this Monte Carlo study is to calculate dose enhancement in tumours by various nanoparticles in prostate brachytherapy using (125)I interstitial implants. ProstaSeed (125)I brachytherapy source was simulated using MCNPX Monte Carlo code. Dose rate constant, radial dose function and anisotropy function values were calculated and compared with previously published data. Dose enhancement factors (DEFs) were calculated for Fe2O3, Ag, Gd, Pt and Au nanoparticles with concentrations of 7, 18 and 30 mg/ml. Our source simulation was validated by comparing our results with previously published data. Maximum DEF values on the central transverse line, within the tumour, for Fe2O3, Ag, Gd, Pt and Au nanoparticles with 30 mg/ml concentration were 1.27, 1.15, 1.14, 1.32, 1.79, respectively. No general trend in DEF with increasing atomic number, or concentration of nanoparticles was observed. However, DEF was the highest for 30 mg/ml concentration of Au. The 50 % isodose line tightened toward the central point of the spherical tumour and the central 100 % isodose line expanded outward. The presence of nanoparticles in a prostate tumour increases the dose inside tumour and decreases the dose outside it, thus the treatment time and source activity can be decreased due to dose enhancement in the tumour. While more preclinical studies on other aspects are necessary, using nanoparticles can be proposed as a useful tool in prostate brachytherapy. Au nanoparticles with higher concentrations can be more useful for this purpose when compared to other nanoparticles.

Tumor bed boost in breast cancer: Brachytherapy versus electron beam

Background:The prospective study aimed to evaluate the effectiveness of Electron beam or HDR 192Ir Interstitial Implant used as a boost in breast Conservation cases after completion of EBRT. The two therapeutic modalities were compared in terms of the following parameters; i.e. cosmesis, optimization of tumor bed boost, local control, toxicity, and DFS.Materials and Methods:The EBRT dose used was 50 Gy in 25 fractions over 5 weeks time. Target delineation of boost treatment was done by CT scan or by high resolution USG. EBRT will be immediately followed by local boost at the primary tumor bearing site of breast with 8 to12 MeV electron beam to a dose of 15 Gy in 6 fractions (Arm A) or with HDR 192Ir interstitial brachytherapy to a dose of 15 Gy in 3 fractions at 6 hours apart (Arm B).Results:The excellent cosmesis achieved with electron beam therapy in Arm A was found to be statistically significant (P = 0.025). Local relapse was absent in both the arms. One distant metastasis occurred in Arm A within 10 months of initiation of treatment and one distant metastasis in Arm B came out within 3 months of starting of therapy.Conclusion:The study has shown good cosmetic result with electron boost and 100% local control with both the technique. However if there is a more number of patients with longer period of follow up we could have got the actual picture to verify our results and assess long term survival data.

Effects of Radioactive Seeds 125 I through Interstitial Implantation on Neoplasm Invasiveness in Xenograft Nude Mice Model of Human Gastric Carcinoma BGC-823

Objective To study the inhibitory effect of radioactive seeds 125I through interstitial implantation on neoplasm invasiveness,and analyze possible mechanisms.Methods The BGC-823cells were subcutaneously injected into the right anterior armpit of BALB/C nude mice in order to establish the model of metastatic tumor.The mice of metastatic tumor were randomly divided into control group and experimental group,and mice from the experimental group were treated by interstitial implantation of 125I for 30,60and 90days,respectively.The tumor inhibitory effect was detected by measuring tumor weigh,size and lung metastasis nodules.The levels of telomerase protein in metastatic tumor,VEGF and bFGF in serum were measured by ELISA,and the expression of p-Erk1/2in tumor was analyzed by Western blot.Results Compared with the control group,tumor weight,size,lung metastasis nodules,and the levels of telomerase protein in metastatic tumor,VEGF and bFGF in serum were significantly decreased due to 125I interstitially implanted.Meanwhile,the expression of p-Erk1/2in tumor was downregulated(P0.05or P0.01),especially for 90-day treatment.Conclusion It could be the mechanism that Erk signal pathway in volved in neoplasm invasiveness is inhibited by radioactive seeds 125I through interstitial implantation in xenograft nude mice of human gastric carcinoma.

The Association of Patient, Tumor, and Treatment Characteristics With Biochemical Response to Neoadjuvant Androgen Deprivation Therapy in Prostate Cancer Patients

Materials/Methods: Nine hundred fifty-two patients with prostate cancer were treated with permanent interstitial implantation as monotherapy using a transrectal ultrasound-guided approach. Real-time intraoperative treatment planning software which incorporates inverse planning optimization was used for all patients. Nine hundred twenty-one patients were treated with I-125 and 31 patients were treated with Pd-103. Two hundred fiftynine patients (27.2%) received neoadjuvant androgen deprivation in most cases to achieve pre-implantation volume reduction for prostate volumes >50 cc. The median prostate volume was 35.9 cc (range, 7.6-99.7 cc). The breakdown between favorable and intermediate risk disease was 79% and 20%, respectively. Dose-volume constraints for this inverse-planning system included: prostate V100 95%, maximal urethral dose 140, the 7 year PSA-RFS was 98% compared to 93% for patients with lower D90 values (p Z 0.01). Multivariate analysis demonstrated that the D90 dose level was the only significant predictor of PSA relapse-free survival (p Z 0.04 value HR 0.32). The median maximum urethral dose was 134%, and the median urethra D20% was 127%. Maximum urethral doses exceeding 150% of the prescription dose were noted in 28% of patients. The median maximum rectal dose was 64% of the prescription dose (range, 29% -193%) and the median volume of the rectum receiving the prescription dose rectum V100 cc was 0.3 cc (range, 0-7.4 cc). No dosimetric parameter was identified linked to late urinary or rectal toxicities. Conclusions: Dosimetric analysis performed on the day of the brachytherapy procedure of a large cohort of patients confirms excellent coverage of the prostate with the prescription dose. Our data demonstrate that the D90 was the single most important variable associated with improved biochemical tumor control in these patients. These data further highlight the critical need for intraoperative real time dose modifications and corrections to achieve optimal dose delivery to the prostate to insure maximal tumor control probability. Author Disclosure: M. Ashamalla: None. M. Kollmeier: None. G.N. Cohen: None. X. Pei: None. M.J. Zelefsky: None.

Determination of Dosimetric Characteristics of IrSeed 125I Brachytherapy Source

Introduction: Low dose rate brachytherapy sources have been widely used for interstitial implants in tumor sites, particularly in prostate. Dosimetric characteristics of a new IrSeed 125I brachytherapy source have been determined using the LiF thermoluminescent dosimeter (TLD) chips. Materials and Methods: Dose rate constant, radial dose function, and anisotropy function around the IrSeed 125I source were measured in a plexiglass phantom using TLD-100 chips. A plexiglass slab phantom with dimensions of 30×30×7.3 cm3 was used to measure dose distribution around the source. Results: Dose rate constant was measured to be equal to 0.965±0.006 cGyh-1U-1. Radial dose function, anisotropy function, and geometry function have been presented as tabulated data for the IrSeed source. Conclusion: Basically, the dosimetric parameters presented here for this new IrSeed source have clinical and treatment planning applications.

Feasibility and safety of CT-guided percutaneous needle biopsy and subsequent iodine-125 seed interstitial implantation for pancreatic cancer

To discuss the feasibility and safety of different approaches for CT-guided percutaneous needle biopsy and subsequent iodine-125 seed interstitial implantation for pancreatic cancer. A retrospective study was carried out on the complete data of 35 patients with pancreatic cancer who have received CT-guided percutaneous needle biopsy with or without subsequent iodine-125 seed interstitial implantation. There were 9 lesions located in the head of pancreas, 20 located in the body, and 6 in the tail. The maximum diameter of the lesions varied from 12 mm to 60 mm (mean 37.1 mm). The patients were treated with a needle in diameter of 16-21G. Operations were undertaken via anterior, posterior and lateral approaches. Thirty-five patients underwent 43 times of CT-guided percutaneous needle biopsies. Thirty-one cases were pathologically diagnosed as cancer, 2 cases inflammatory lesions, and 2 were suspected tumors (one of which was finally diagnosed as cancer, while another was pancreatic pseudocyst). The ratio of correct diagnosis was 94.3%. Fourteen patients were treated subsequently with CT-guided iodine-125 seed interstitial implantation therapy, with a total of 65 times of needle puncture. The operations were performed via direct approach to the tumor in 18 cases, transhepatic approach in 2 cases, transgastric approach in 4 cases, transintestinal approach in 10 cases, and through mesenteric vessels in one case. Incidence of complications in the biopsy group was 2.32% (1/43), and in the implantation group was 6.15% (4/65), with a statistically non-significant difference (P = 0.600) between the two groups. Incidence of complications in the group using 16-18G needle was 4.65% (4/86), while in the group using 20-21G needle was 4.55% (1/22), also with a non-significant difference (P = 0.064). The accuracy rate of needle biopsy in this study was 94.28% (33/35). CT-guided percutaneous needle biopsy and subsequent iodine-125 seed interstitial implantation are both feasible and safe for pancreatic cancer.

Computed tomographic-guided iodine-125 interstitial implants for malignant thoracic tumors

PurposeTo evaluate the feasibility and efficacy of percutaneous interstitial brachytherapy using iodine-125 (125I) radioactive seeds under computed tomographic (CT) guidance for malignant thoracic tumors. Materials and methodsForty-one patients (34 males, 7 females; 18–90 years; mean, 63.7 years) with 77 lesions (3 in the mediastinum, 7 in the chest wall, 67 in the lung) underwent percutaneous interstitial implantation of 125I radioactive seeds under CT guidance. A treatment planning system (TPS) was employed to calculate the number and distribution of seeds preoperatively. An 18-G needle was inserted into the lesions under CT guidance and send the seeds according to TPS. Two patients with mediastinal lesions undergoing seed implantation received an artificial pneumothorax. One patient with lung carcinoma adjacent to the anterior mediastinum underwent seed implantation through the sternum. Follow-up CT was done every 2 months postoperatively. ResultsThe procedure was successful in all patients. No major procedure-associated death occurred. The mean duration of follow-up was 19.4±1.3 months (3–49 months). A complete response (CR) was seen in 49 lesions (63.6%), partial response (PR) in 9 lesions (11.7%), stable disease (SD) in 12 lesions (12.8%), and progressive disease (PD) in 7 lesions (7.4%). The overall response rate (CR+PR) was 75.3%; the local control rate (CR+PR+SD) was 90.9%. The 1-, 2- and 3-year progression-free rates for local tumors were 91%, 88% and 88%, respectively. The 1-, 2- and 3-year survival rates were 87%, 74% and 68%, respectively. ConclusionImplantation of CT-guided 125I seeds is feasible and effective for patients with malignant thoracic tumors.

CT-Guidance Allows Interstitial Implantation in an Outpatient Setting for Cervical Cancer Patients

Cervical cancer patients with disease extending laterally into parametrial tissue often require interstitial trans-perineal implantation under general anesthesia and a hospital stay for brachytherapy treatments. A major disadvantage of intraoperative implantation is the lack of 3D image guidance during needle placement. Here, we describe real-time CT-guidance to allow interstitial implantation of catheters with the Utrecht Fletcher Applicator® (Nucletron™) in an ambulatory setting. Following a mild oral analgesic and an anxiolytic, patients are placed on the CT simulator couch in the treatment position. The Utrecht tandem and ovoid (T&O) is inserted and a CT scan of the pelvis performed to confirm appropriate geometry. Delineating the extent of disease and organs at risk on the CT scan allows determination of the optimal number, distribution, and depth of insertion of each interstitial catheter. A CT is repeated after insertion of each catheter and adjustments are made in real time. Once all interstitial catheters are implanted, a final CT is performed for 3D optimization brachytherapy planning. Without movement or manipulation, the patients are then treated with HDR brachytherapy on the CT simulator couch. Following therapy, the Utrecht T&O applicator and interstitial needles are removed and patients are discharged home. A total of 77 treatments were performed in 18 patients. Ten out of eighteen patients (56%) required 2 or fewer needles placed to adequately dose the extent of disease. Persistent vaginal bleeding after removal of the applicator was observed in 4 patients necessitating an inpatient stay for close observation with 2 patients requiring blood transfusions. Only one did not continue with the interstitial implantations and was treated with standard T&O implant followed by an external beam parametrial boost. All other patients tolerated the treatments well with no complications documented. Real-time CT-guided administration of interstitial catheters using the Utrecht applicator allows for proper positioning into parametrial disease. These implants are tolerated well and can be performed safely in an outpatient setting, obviating the need for placing interstitial needles in the operating room without 3-D image guidance.

Percutaneous vertebroplasty combined with interstitial implantation of 125I seeds in banna mini-pigs

BackgroundAlthough brachytherapy is one of the most effective ways to treat metastatic spinal tumor with little damage to surrounding healthy tissue, it may cause radiation myelopathy if an overdose occurs. Establishing a valuable animal model can help to find a method to overcome its complications. In the current study, we set up a banna mini-pig model to mimic percutaneous vertebroplasty with 125I seed implantation.MethodsPercutaneous vertebroplasty (PVP) combined with interstitial implantation of 125I seeds, 125I seeds were transplanted into the vertebral body at the T13 level of the spine in banna mini-pigs. After raising them for up to eight months, the spinal cord and vertebral body were collected for pathological analysis.ResultsA potential animal model had been successfully established, no case of radiation myelopathy was found in any of the treated banna pigs, and no significant cellular impairment was noted by pathological analysis.ConclusionsIt proves that PVP with 125I brachytherapy is an effective method to treat metastasis spinal tumor, and that the banna mini-pig can be a suitable model to investigate the mechanism of brachytherapy complications.

Comparison of Preplanning and Intraoperative Planning for I-125 Prostate Brachytherapy

To compare two widely used permanent prostate brachytherapy techniques, preplanning and intraoperative planning, based on postimplant dosimetry, toxicity and biochemical outcomes. Between 2003 and 2006, 665 men with localized prostate cancer were treated with permanent interstitial implantation. The first 227 consecutive men were treated with the preplanning technique, followed by 438 men treated with the intraoperative technique. Late toxicity was scored by the Common Terminology Criteria for Adverse Events v.4.0. Biochemical failure was defined as a prostate-specific antigen increase of more than 2 ng/ml above the nadir value excluding a benign bounce. Univariate and multivariate analyses were performed to identify the variables associated with biochemical failure-free survival. Postimplant target coverage was similar in the two groups, with a small difference in risk organ doses. Mean V100 was 96.3 vs. 96.7% (P = 0.205), D90 was 119.6 vs. 119.4% (P = 0.884), urethral D10 was 157.5 vs. 146.1% (P = 0.010), rectal V100 was 0.57 vs. 0.43 cc (P = 0.002) in the preplanning and intraoperative planning groups, respectively. Acute and late Grade 3 genitourinary and gastrointestinal toxicities were <1% for both methods. The 5-year biochemical failure-free survival rate was 95.4% for the preplanning and 94.0% for the intraoperative planning group (P = 0.776). Multivariate analysis revealed Gleason score, biopsy positive rate and V100 to be predictors of biochemical failure-free survival, while the planning technique was not significant. This large-scale analysis of high-quality implants revealed similar postimplant dosimetry, toxicity profiles and biochemical failure-free survival for the preplanning and intraoperative planning methods.

Study of treatment using percutaneous acetabuloplasty and interstitial implantation of 125I seeds for patients with metastatic periacetabular tumors

BackgroundThe periacetabular area is one of the primary sites of metastatic tumors, which often present as osteolytic bone destruction. Bone destruction in the acetabulum caused by metastatic tumors will cause hip pain and joint dysfunction. It results in decreased quality of life for patients. The aim of our study was to explore the clinical effect of metastatic periacetabular tumors treated with percutaneous cementoplasty and interstitial implantation of 125I seeds.MethodsA retrospective analysis was performed on 24 patients with metastatic periacetabular tumors who underwent combined therapy of percutaneous acetabuloplasty and interstitial implantation of 125I seeds between February 2003 and June 2011. There were 13 males and 11 females aged 19–80 years with a mean age of 57.3. The primary tumor site was the lung in eight cases, the breast in six, the prostate cancer in eight, and the liver in two. The amount of implanted 125I seeds was 12–20 seeds/person, with a mean of 16.5 seeds/person, and the matching peripheral dosage (MPD) was 80~100Gy. Routine postoperative chemotherapy and other combined treatments were applied to patients after the surgical operation. Changes in the Karnofsky Score(KPS), Harris Hip Score(Harris), and Visual Analog Scale(VAS) were observed during the follow-up period.ResultsThe 24 patients’ operations were all successful. No major complications occurred. Complete pain relief was achieved in 58% (14 of 24) of patients, and pain reduction was achieved in the 42% remaining (10) patients. The mean duration of pain relief was 8.3 months. Pain recurred in one patient 3 months after surgery. Six patients had died and 18 patients were alive at the time of the 1-year follow-up. Comparing the KPS, Harris and VAS scores pre- and postoperativelyat 1, 6, and 12 months, the combined therapy method was significantly effective in metastatic periacetabular tumor patients (P<0.05).ConclusionsPercutaneous cementoplasty with interstitial implantation of 125I seeds is an effective treatment method for metastatic periacetabular tumor patients, providing tumor resistance, pain relief, increased bone stability, and improved quality of life for patients.

Stereotactic Body Radiation Therapy (SBRT) Can Be Dosimetrically Equivalent to High-dose Brachytherapy as a Boost for Locally Advanced Cervical Cancer— A New Clinical Trial Concept

Current standard of care for locally advanced cervical cancer consists of external beam radiation plus local boost therapy with intracavitary brachytherapy (BT). Intracavitary HDR procedures are invasive and require anesthesia to accommodate the insertion of intrauterine treatment devices. In addition to requiring technical skill, BT treatments lack reproducibility. Furthermore, BT uses sources, which result in rapid dose fall off therefore intracavitary treatment, may be ineffective in delivering dose to periphery of bulky advanced tumors; treatment of peripheral disease requires interstitial implants, which are technically challenging. Given the recent advances in conformal stereotactic therapy it is now possible to deliver high doses of radiation to confined volumes while sparing normal tissue. As the initial step towards a clinical trial, we performed a dosimetric comparison of SBRT to HDR BT for the definitive treatment of locally advanced cervical cancer. A total of 5 patients with FIGO stage IIIB cervical cancer were selected. Planning CT's from initial BT treatments were obtained, and were then imported for treatment planning. OARs and HR-CTVs were defined using GEC-ESTRO guidelines. Plans were created using 13 non opposed non coplanar intensity modulated beams (6 or 18 MV) for a total dose of 2550 cGy in 3 fractions (LQED2GY equivalent of 40 Gy). Contours and planning CT's were then imported into the Brachyvision treatment planning system for HDR BT planning using the same fraction size. HDR dose was optimized to point A and the HR-CTV. LQED 2 Gy of 2 cc doses to the bladder, rectum, small bowel, and sigmoid as well as the D90 of the CTV were then calculated and compared between plans per GEC-ESTRO guidelines. Given the ideal GEC-ESTRO tolerance dose for the rectum and sigmoid is 30 Gy and 45 Gy for the bladder, SBRT resulted in an average LQED 2 Gy to the bladder, rectum, small bowel, and sigmoid of 37.6 (29.1-45.5), 32.4 (16.8-51), 27.9 (21.3-36.7), and 27.9 (1.64-39.1) Gy respectively, while BT resulted in doses of 36.1 (28.3-52.1), 29.4 (16.2-50.4), 54.3 (24.4-88.6), 40.5 (24.8-77.8) Gy respectively. High Risk CTV D90 dose for SBRT was 41.1 Gy (40.8-41.7) and 35.4 (23.5-46.7) for BT. SBRT boosts result in higher more conformal dose to the tumor while maintaining similar doses to OAR in this subset of patients. SBRT is at the least dosimetrically equivalent to HDR BT in the treatment of locally advanced cervical cancer with respect to dose delivered to OAR and may exceed BT with regard to total dose delivered to the tumor. Given our small sample size further work is required. Using this data we hope to undertake a clinical trial to determine the feasibility of SBRT in the definitive treatment of locally advanced cervical cancer.

A rare cause of rectal ulceration

rostate cancer is the most common neoplasm affecting en, with an estimated 4,000 new cases diagnosed each ear in Portugal.1 Currently, curative treatment options for en with localized prostate cancer include radical prostaectomy, external beam radiotherapy (EBRT) and prostate rachytherapy (BT) with permanent interstitial implants. his later modality is being increasingly used because it rovides similar disease control with lower rates of inconinence and sexual dysfunction. However, it can lead to hronic radiation proctitis, because of the close proximty between the rectum and the implanted prostate.2 The ain manifestations of chronic radiation proctitis are rectal leeding, urgency, pain, strictures, mucous discharge and ncontinence and they may take up to two years to develop. he association of BT with EBRT raises the incidence of procitis from 1--19% to 39%.3 Treatment options include medical therapy (aminosalicyates, sucralfate, steroid enemas and hyperbaric oxygen), ndoscopic therapy preferably with argon plasma coaglation (safer, less expensive and more widely available han heater and bipolar cautery, Nd:YAG laser and topical

Postoperative125I brachytherapy delivered by digital model obturators for recurrent or locally advanced maxillary cancers

We aimed to evaluate the feasibility and effectiveness of postoperative (125) I brachytherapy delivered by use of digital model obturators for recurrent or locally advanced maxillary cancers. Retrospective study. From 2006 to 2008, 12 patients (seven females; median age, 65 years; range, 22-86 years) with recurrent or locally advanced maxillary cancers showing positive margins after surgery underwent (125) I brachytherapy by use of digital model obturators and interstitial implants. The radioactivity was 18.5 to 33.3 MBq per seed, and the prescription dose was 80 to 160 Gy. Functional outcome of patients was evaluated by the Performance Status Scale (PSS) for head and neck cancer before and after brachytherapy. The (125) I seeds and dosages were well distributed in the radiation fields, and all patients had higher PSS scores after than before treatment with obturators. During a median follow-up of 53 months (range, 28-62 months), local control at 3 and 5 years was 83.3% and 66.7%, respectively, with a mean local control time of 53.5 ± 3.79 months. Overall survival at 3 and 5 years was 91.7% and 71.4%, respectively, with a mean survival time of 56.6 ± 2.99 months. Two patients died due to local recurrence, and one patient died due to lung metastasis. No patient had severe complications during follow-up. (125) I brachytherapy delivered by digital model obturator is effective in treating maxillary cancers with positive margins after maxillectomy for advanced or recurrent cancer. The method may improve the quality of life of patients with maxillary defects. Laryngoscope, 2012.

The treatment of non-small cell lung cancer by interstitial I-125 seeds implantation combined with chemotherapy and Chinese medicine

To investigate the effects of brachytherapy with computed tomography-guided percutaneous radioactive I-125 seeds interstitial implantation (ISI) synchronized chemotherapy and Chinese medicine (CM) for the treatment of advanced stage of non-small cell lung cancer (NSCLC). Ninety patients diagnosed with NSCLC by biopsy were randomly assigned to three groups: the synchronized therapy group (A), the chemotherapy plus CM-treated group (B), and the chemotherapy-treated group (C); a 2-month course of treatment was administered to them all. The effectiveness of treatment was evaluated based on tumor size, tumor markers (carcinoembryonic, squamous cell carcinoma-associated antigen, and cytokeratin 19 fragment), clinical symptoms, and quality of life (QOL) in patients. The total effective rates of Groups A to C were 83.33%, 46.67%, and 43.33%, respectively. The tumor markers were reduced obviously in Group A, showing signifificant difference compared with those in the other two groups. Additionally, QOL was elevated and cancer-related symptoms were alleviated more signifificant in Group A than those in Group C (all P<0.05). The synchronized therapy of I-125 implantation with chemotherapy and CM was a safe therapeutic method and can be regarded as a new mode for treatment of advanced-stage NSCLC.

Novel Approach to Surgical Repair of Enterovaginal Fistula in the Irradiated Pelvis

Novel Approach to Surgical Repair of Enterovaginal Fistula in the Irradiated Pelvis

70P Role of Interstitial Brachytherapy in Early Stage Breast Cancer

AimTo assess the quality of high dose rate interstitial implants in breast cancer by using different volumetric indices and to correlate them with skin and subcutaneous tissue toxicities. BackgroundIn recent years brachytherapy by using high dose rate with Ir192 source for partial breast irradiation as well as boost after external irradiation has been an established modality of treatment of early breast cancer. Despite the advantages of brachytherapy with regard to tumor control, maintaining good cosmesis and minimum skin and subcutaneous tissue toxicity is important. Materials and methodsOut of 25 patients, who were selected for interstitial implants after undergoing breast conservation surgery, ten were treated radically with 34 Gy in 10 fractions in 5 days @ 3.4 Gy twice daily and 15 patients received boost dose of 12 Gy in 4 fractions @ 3 Gy twice daily. The median follow up was 20 months. During each follow up assessment of late skin and subcutaneous tissue toxicity as per RTOG criteria was done. Various dosimetric indices were analysed. Dose Volume Histogram for dose per unit volume of skin for 10cc, 5cc, 2cc, 1cc, 0.1cc and 0.01cc was calculated. Best estimates and correlation of toxicity was revealed by assessment of Dose Non-uniformity Ratio (DN R) which also correlated well with geometry defining indices like Uniformity Index (UI). ConclusionVolumetric assessment of skin dose for less than 2 cc correlated most with toxicity. DNR and UI can help us to assess and correlate late skin and subcutaneous tissue toxicity and thus serve useful to determine the quality of implant. DisclosureAll authors have declared no conflicts of interest.

High-dose-rate interstitial computed tomography–based brachytherapy for the treatment of cervical cancer: Early results

PurposeThere is limited published data on high-dose-rate interstitial brachytherapy (HDRBT) for cervical cancer resulting in no consensus on a fractionation schedule. This study reports our experience of CT-based HDRBT for treating locally advanced cervical cancer. Methods and MaterialsForty-seven patients diagnosed with Stage IIB–IVA cervical cancer not suitable for intracavitary brachytherapy were treated with HDRBT from March 2005 to November 2010. All patients received external beam radiation therapy with a median dose of 45Gy and all had one interstitial implantation followed by 3.75–5Gy×5 fractions in a twice daily (BID) schedule. Total doses for clinical target volume and organs at risk, including rectum, bladder, and sigmoid, were summated and normalized to a biologically equivalent dose of 2Gy per fraction. At 3 months posttherapy, early response was assessed with clinical examination and positron emission tomography (PET/CT) imaging. ResultsMedian clinical target volume D90 (dose delivered to 90% of the clinical target volume) was 76.3 (59.0–86.9) Gy and the 2cc dose to the bladder, rectum, and sigmoid colon organs were 70.2 (55.9–77.7), 65.8 (54.9–80.6), and 56.5 (45.0–71.2) Gy, respectively. Posttreatment, 12 patients had evidence of persistent disease on PET/CT. Eleven of the 35 patients who had complete response developed recurrences. Two patients developed late Radiation Therapy Oncology Group ≥3 rectal toxicities. Two-year actuarial local control, disease-free survival, overall survival, and Grade ≥3 toxicities were 61%, 43%, 59%, and 10%, respectively. ConclusionOur approach of a single implantation procedure followed by five fractions of HDRBT was well tolerated with early results demonstrating a moderate response and local control rate with acceptable toxicities.

Brachytherapy catheter spacing and stabilization technique

Purpose/ObjectivesTo facilitate catheter spacing, implant stability, and patient comfort during multicatheter interstitial brachytherapy. Methods and MaterialsUniform and consistent spacing of multiple interstitial implant catheters can be difficult because individual catheters may become displaced during the course of treatment. The authors have developed a brachytherapy catheter fixation method using Jackson-Pratt (JP) drains that can be used within wounds to maintain catheter spacing or on the skin surface for applicator fixation. JP drains are threaded over the implant needles to space and stabilize the implant geometry. The needles are then replaced with the usual brachytherapy catheters. ResultsSurgically directed (“open”) placement of implant catheters is less prone to displacement when a drain connects and spaces the catheters in the wound. Fixation on the skin surface can also be achieved with the JP drains, which make the friction buttons optional. The soft drain material helps avoid discomfort and pressure injury sometimes associated with hard plastic buttons. Small (10 French) round JP drains are suitable for breast, and head and neck sites and larger 7×10-mm flat JP drains for extremity sarcomas, abdominal, or thoracic tumors. ConclusionsThe complex brachytherapy devices fashioned from widely available surgical drains effectively guide and maintain geometry for multicatheter interstitial implants. Stable implant geometry leads to more reliable implementation of brachytherapy dosimetry. Patient comfort is improved and soft tissue injury from hard-edged buttons is avoided.