Intraoperative High-dose-rate Brachytherapy Research Articles

Systematic review of intraoperative radiation therapy for head and neck cancer.

Multidisciplinary treatments with surgery, radiation therapy, and chemotherapy are the cornerstones in the management of locally advanced head and neck malignancies. In most cases, radiation is delivered via external beam radiation therapy (EBRT). Intraoperative radiation therapy (IORT), on the other hand, is the delivery of precise doses of radiation to selected target volumes within the exposed surgical field while at the operating room. Most studies on its use on head and neck cancers are limited to single-institutional retrospective case series. We performed a systematic review to consolidate the existing literature on IORT for head and neck malignancies. Fifty-two studies representing a mixed population of 2,389 patients were included in this review. IORT via electrons (intraoperative electron radiation therapy), brachytherapy (intraoperative high dose-rate brachytherapy) or photons was administered in numerous settings, but most commonly as part of a reirradiation regimen following salvage surgery for recurrent tumours. Often, additional EBRT was also planned postoperatively. This review illustrates that IORT is a promising treatment modality in head and neck cancer. Multiple single-institutional studies spanning several decades have demonstrated benefit in terms of local control with reasonable toxicity. However, randomised trials comparing it with current standards of care are still needed.

Evaluation of a Model-based Dose Calculation Algorithm (Acuros) for Intraosseous High Dose Rate Brachytherapy (HDR) With Intramedullary Nailing for Bone Metastases

A standard practice for patients with long bone metastases after intramedullary nailing is treatment with postoperative two-dimensional external beam radiotherapy (2D EBRT), delivered to the length of the implanted hardware. Our goal is to use intraoperative, intraosseous HDR brachytherapy delivered prior to intramedullary nailing to deliver an ablative dose to a limited volume immediately surrounding the tumor. This work evaluates the dosimetric effects resulting from treatment through a metal intramedullary drill bit, which in turn, dramatically reduces the volume potentially harboring subclinical contamination from the drill path and subsequent intramedullary nail placement. A model-based dose calculation engine was commissioned using the IROC data-set. Additionally, the accuracy of dose calculations was verified at several distances from the source in water using a custom 3D-printed phantom with a series of concentric rings holding Gafchromic-EBT3 film. A separate set of films from the same batch was calibrated with a 6MV-LINAC beam. Treatment plans were generated for two different source configurations (a single dwell position and a linear array of dwell position) with a standard 4.7Fr catheter surrounded by the stainless-steel drill bit. Measurements were performed at 1cm, 2cm, 3cm, 4cm, and 5cm from the active source and compared with dose calculations from the TG-43 and Acuros algorithms. Without the drill bit surrounding the catheter, measurements were in good agreement with the dose calculated by the treatment planning system (<1.0% on average). The maximum dose deviation (1.5%) was observed at 1cm from the source, as expected due to the steep dose gradient. With the stainless-steel drill bit surrounding the catheter, the Acuros dose calculations agreed with film measurements (<1.5% on average) with the largest difference at 1cm (<2.5%). Using TG-43 for dose calculation, we observed larger deviations from measurements (average 6.3%). At larger distances, 5cm, the agreement is within <1% of the calculated dose by Acuros. A model-based dose calculation engine was commissioned using a consensus dataset. This dose engine was secondarily verified with film measurements about a linear catheter surrounded by a stainless-steel intramedullary drill bit for the purpose of facilitating accurate dose calculations for intraoperative HDR brachytherapy of long bone metastases.

Intraoperative high dose rate brachytherapy during breast-conserving surgery: A prospective pilot study.

To evaluate feasibility, quality of life, toxicity, and cosmetic outcome for intraoperative breast cancer brachytherapy after breast-conserving surgery using high dose rate brachytherapy. Fifty-two consecutive women, ⩾50 years old, diagnosed with a unifocal non-lobular breast cancer ⩽3 cm, N0, underwent breast-conserving surgery and sentinel node biopsy. Twenty-five women received intraoperative brachytherapy pre-pathology at primary surgery and the others post-pathology, during a second procedure. An applicator, connected to a high dose rate afterloader, was used. Two of the women were excluded due to metastases found per-operatively at a frozen section from the sentinel node. Quality of life was evaluated using two validated health questionnaires. Treatment toxicity was documented according to the LENT-SOMA scale by two oncologists. The cosmetic result was evaluated using the validated freely available software BCCT.core 2.0. The clinical procedure worked out well logistically. Seven women received supplementary external radiotherapy due to insufficient margins and, in one case, poor adaptation of the breast parenchyma to the applicator. No serious adverse effects from irradiation were registered. The results from the health questionnaires showed no major differences compared with reference groups from the Swedish population. Only two women were registered as having a "poor" cosmetic result while a majority of the women had a "good" outcome. This pilot study shows that intraoperative brachytherapy is a feasible procedure and encourages further trials evaluating its role in treatment of early breast cancer.

Comparison of Lung Dose in Breast Cancer Treated with Intraoperative High Dose Rate Brachytherapy versus Adjuvant External Beam Radiation Therapy

Comparison of Lung Dose in Breast Cancer Treated with Intraoperative High Dose Rate Brachytherapy versus Adjuvant External Beam Radiation Therapy

Accuracy assessment of a\xa0potential clinical use of navigation-guided intra-operative liver metastasis brachytherapy\u2014a\xa0planning study

For patients with inoperable liver metastases, intra-operative liver high dose-rate brachytherapy (HDR-BT) is a promising technology enabling delivery of a high radiation dose to the tumor, while sparing healthy tissue. Liver brachytherapy has been described in the literature as safe and effective for the treatment of primary or secondary hepatic malignancies. It is preferred over other ablative techniques for lesions that are either larger than 4 cm or located in close proximity to large vessels or the common bile duct. In contrast to external beam radiation techniques, organ movements do not affect the size of the irradiated volume in intra-operative HDR-BT and new technical solutions exist to support image guidance for intra-operative HDR-BT. We have retrospectively analyzed anonymized CT datasets of 5 patients who underwent open liver surgery (resection and/or ablation) in order to test whether the accuracy of a new image-guidance method specifically adapted for intra-operative HDR-BT is high enough to use it in similar situations and whether patients could potentially benefit from navigation-guided intra-operative needle placement for liver HDR-BT.

Intraoperative High Dose Rate Brachytherapy Can Be Used to Salvage Patients with Previously lrradiated Head and Neck Recurrences

Purpose: To develop a novel technique, intraoperative high-dose rate brachytherapy (IOHDR), in the treatment of previously irradiated head and neck cancers located at anatomical sites inaccessible to intraoperative electron beam radiotherapy (IOERT). &#x0D; &#x0D; Methods: Between October 1992 and June 1997, seven patients (median age=65 years; range=52 to 71 years) with previously irradiated head and neck recurrences at anatomical sites inaccessible to IOERT in the base of skull were treated with IOHDR after maximal resection for microscopic residual disease. Treatment volume ranged from 6 cc to 24 cc. Six patients received 15 By of IOHDR at 0.5 cm; one received 10 By using custom-made surface foam applicators. &#x0D; &#x0D; Results: The median follow-up was 59 months (range 33 to 67 months). It was technically feasible to deliver IOHDR in all seven patients at sites that were inaccessible to IOERT. The morbidity (observed in two patients) was acceptable and generally surgically related. Four of seven patients (57%) were locally controlled at IOHDR site. Two failed regionally, outside the IOHDR treated sites. The disease-free survival ranged from 3 to 30 months (median 9 months) with two patients still alive, disease-free at 28 and 30 months. &#x0D; &#x0D; Conclusions: IOHDR can be used, with limited toxicity, to treat previously irradiated head and neck cancers at sites inaccessible to IOERT. We are currently evaluating the addition of limited EBRT dose to improve the local control of these poor prognosis recurrent tumors.

Automated construction of an intraoperative high-dose-rate treatment plan library for the Varian brachytherapy treatment planning system

PurposeThe ability to create treatment plans for intraoperative high-dose-rate (IOHDR) brachytherapy is limited by lack of imaging and time constraints. An automated method for creation of a library of high-dose-rate brachytherapy plans that can be used with standard planar applicators in the intraoperative setting is highly desirable. Methods and MaterialsNonnegative least squares algebraic methods were used to identify dwell time values for flat, rectangular planar applicators. The planar applicators ranged in length and width from 2 cm to 25 cm. Plans were optimized to deliver an absorbed dose of 10 Gy to three different depths from the patient surface: 0 cm, 0.5 cm, and 1.0 cm. Software was written to calculate the optimized dwell times and insert dwell times and positions into a .XML plan template that can be imported into the Varian brachytherapy treatment planning system. The user may import the .XML template into the treatment planning system in the intraoperative setting to match the patient applicator size and prescribed treatment depth. ResultsA total of 1587 library plans were created for IOHDR brachytherapy. Median plan generation time was approximately 1 minute per plan. Plan dose was typically 100% ± 1% (mean, standard deviation) of the prescribed dose over the entire length and width of the applicator. Plan uniformity was best for prescription depths of 0 cm and 0.5 cm from the patient surface. ConclusionsAn IOHDR plan library may be created using automated methods. Thousands of plan templates may be optimized and prepared in a few hours to accommodate different applicator sizes and treatment depths and reduce treatment planning time. The automated method also enforces dwell time symmetry for symmetrical applicator geometries, which simplifies quality assurance.

Intraoperative high dose rate brachytherapy (HDR-IORT) in locally advanced rectal cancer

Intraoperative high dose rate brachytherapy (HDR-IORT) in locally advanced rectal cancer

Intraoperative Electron Irradiation for Locally Recurrent Colorectal Cancer

Intraoperative electron radiation therapy (IOERT) has been used at Mayo Clinic as a component of therapy for patients (pts) with locally advanced recurrent colorectal cancer since 1981. This review was performed to evaluate survival, relapse patterns, and prognostic factors in patients with colorectal cancer relapse treated with curative intent. Between April 1981 and February 2008, 607 pts with locally recurrent colorectal cancer received IOERT as a component of therapy. The population includes 238 females and 369 males with a median age of 62 years (range, 21-87). The median interval from primary diagnosis to recurrence was 27 months. External beam radiotherapy (EBRT) had been previously delivered to 271 pts (45%) and chemotherapy (CT) to 364 (60%). Maximum resection with IOERT was preceded or followed by EBRT (median dose 4550 cGy, range 500-6500 cGy) in 583 pts (96%). CT was delivered concomitantly with EBRT in 492 pts (81%) while maintenance CT was administered in 107 pts (18%). Surgical resection at time of IOERT was classified as R2 (gross residual) in 156 (26%), R1 (microscopically positive margins) in 224 (37%), and R0 (negative margins) in 227 (37%). IOERT was delivered with 6-20 MeV electrons in doses ranging from 750-3000 cGy (median 1500 cGy). Two patients were treated with intraoperative high dose rate brachytherapy. Endpoints include survival (OS), local relapse (LF), central relapse within the IOERT field (CF), and distant metastases (DM). All pts have been followed until death or a median of 44 months for survivors. OS at 5 years was 30%, LF was observed in 38%, CF in 19%, and DM in 62%. Resection margin status was predictive for OS, LF, and DM. 5-yr OS was 46%, 27%, and 16% for R0, R1, and R2 resection, respectively (p < 0.0001). LF at 5 years was observed in 26%, 44%, and 51% (p = 0.003), CF in 11%, 24%, and 24% (p = 0.03), and DM in 53%, 62%, and 73% (p < 0.0001) for R0, R1, and R2 resection, respectively. On multivariate analysis, R0 resection, no prior CT, use of systemic maintenance CT, and IOERT after 1996 predicted for OS, and 59% of pts with 3 or more favorable factors were 5-yr survivors. R1-2 resection, prior EBRT, and IOERT before 1997 predicted for LF, and prior CT, R1-2 resection, and IOERT before1997 predicted for DM. Toxicity grade ≥3 partially attributable to IOERT was observed in 66 pts (11%). Neuropathy was observed in 133 pts (22%) including 37 (6%) with grade 1, 64 (11%) with grade 2, and 37 (6%) with grade 3 neuropathy. Long term survival and disease control is achievable in pts with locally recurrent colorectal cancer. Prognosis is best in less heavily pre-treated pts who receive systemic CT following an R0 resection and has improved in the past decade. Continued evaluation of curative intent combined modality therapy including IOERT is warranted in this high risk population.

Retrospective analysis of dose delivery in intra-operative high dose rate brachytherapy

Background. This study was performed to quantify the inaccuracy in clinical dose delivery due to the incomplete scatter conditions inherent in intra-operative high dose rate (IOHDR) brachytherapy. Methods. Treatment plans of 10 patients previously treated in our facility, which had irregular shapes of treated areas, were used. Treatment geometries reflecting each clinical case were simulated using a phantom assembly with no added build-up on top of the applicator. The treatment planning geometry (full scatter surrounding the applicator) was subsequently simulated for each case by adding bolus on top of the applicator. Results. For geometries representing the clinical IOHDR incomplete scatter environment, measured doses at the 5 mm and 10 mm prescription depths were lower than the corresponding prescribed doses by about 7.7% and 11.1%, respectively. Also, for the two prescription methods, an analysis of the measured dose distributions and their corresponding treatment plans showed average decreases of 1.2 mm and 2.2 mm in depth of prescription dose, respectively. Conclusions. Dosimetric calculations with the assumption of an infinite scatter environment around the applicator and target volume have shown to result in dose delivery errors that significantly decrease the prescription depth for IOHDR treatment.

Intraoperative High-Dose-Rate Brachytherapy (IBT) for Locally Unresectable Intraabdominal Malignancy

Purpose: Intraoperative high-dose-rate brachytherapy (IBT) has been successfully used in locally advanced unresectable intraabdominal malignancy. We retrospectively evaluated the safety, feasibility, and general outcome of IBT following cytoreductive surgery.Patients and methods: After radical resection, the target area to be treated by IBT was determined jointly by the surgeon and the radiation oncologist. A silicon template was used to position parallel hollow catheters spaced 1 cm apart against the area of interest. IBT doses were prescribed at 1 cm depth from the template surface and calculated using standard plans. Radiation was administered in a dedicated shielded room.Results: Between August 2001 and February 2006, 10 patients (colorectal cancer n = 6, cervix cancer n = 1, extramedullar plasmocytoma n = 1, liposarcoma n = 1 and sacrococcygeal teratocarcinoma n = 1) were treated. The mean delivered IBT dose was 8 Gy (range 7.5-20). No postoperative mortality was seen, while major complications developed in one (10%) patient with a rectovaginal fistula and intraabdominal abscess. Five of the six colorectal cancer patients developed local recurrence while 3 also developed distant metastases. The mean disease-free and overall survival in this group was 8.5 months (range 4–15) and 25.5 months (range 10–48) respectively. Palliation of symptoms was observed in 89 % of cases.Conclusion: IBT combined with debulking surgery is feasible and can be safely performed. While cure is rarely achieved, IBT offers the potential to prolong local control and survival in locally unresectable intraabdominal cancer. Therefore, IBT can be considered as a valuable adjuvant in the therapeutic and palliative armamentarium in these selected patients.

SU‐FF‐T‐170: Dose Delivery to Curved Structures in Intra‐Operative High Dose Rate (IOHDR) Brachytherapy

Purpose: To investigate the magnitude of overdosage / underdosage for curved surfaces in intra‐operative high dose rate (IOHDR) brachytherapy when the original treatment plan assumed a planar geometry. Method and Materials: The archived IOHDR brachytherapy treatment plans of 5 cases were used in this study. Plans of 3 patients treated in our facility were chosen for the different treatment surface areas and two plans with square fields were developed to compare with irregular shape of clinical cases. Phantoms with four various radii (5 cm to 13.5 cm) were used to simulate the treatment planning geometries which were calculated in 2‐dimensional plans. EDR2 radiographic film dosimetry was used to evaluate the dose distribution for each case. Each film was digitized with 0.17 mm resolution using a film dosimetry system and converted to dose. Results: A 2‐D planar implant was designed to deliver a dose of 200 cGy to the prescription depth. This implant applicator was then wrapped around curved phantoms of different radii and the identical treatment was delivered for each curved structure. However, the actual doses delivered to the prescription points were about 9 % (5.5 % for small treatment area − 3 catheter × 4 cm2) higher for the convex with respect to the prescription point with 5 cm radius at 1 cm prescription distance. The actual delivered dose was increased linearly proportional to decreasing of the radius of convex. Conclusion: In IOHDR clinical cases, 2‐dimensional planning geometry is typically used without considering the curved shape of the patient's structure. Our measurements have shown an overdosage when the original planar treatment plan was delivered in a convex setting resulting in an increase in the prescription depth which may be clinically relevant.

The challenging role of radiation therapy for very young children with rhabdomyosarcoma

To evaluate local control and toxicity for very young children treated with multimodality therapy for rhabdomyosarcoma (RMS). From 1990 to 2004, 20 patients<or=36 months at diagnosis were treated at our institution. Nineteen underwent chemotherapy (CMT), surgery and/or intraoperative high-dose-rate brachytherapy (IOHDR), and external-beam radiation (EBRT). Median age was 17 months. Sites included extremity (7), trunk (5), parameningeal (4), orbit (1), head/neck (1), bladder/prostate (1). Histologies consisted of 10 embryonal (53%) and 9 alveolar/undifferentiated (47%). Ten had delayed gross total resection (GTR) at median time of 17 weeks after the start of CMT, and 8 of these underwent IOHDR. Median interval between start of CMT and EBRT was 18 weeks. Median EBRT dose was 36 Gy. EBRT technique was either intensity-modulated (11), three-dimensional (3), or two-dimensional (5). Functional outcome was assessed for patients alive>or=1 year after diagnosis (15) in terms of mild, moderate, or severe deficits. Median follow-up was 33 months for survivors and 23 months for all patients. Two-year actuarial local control, event-free survival, disease-specific survival, and overall survival were 84%, 52%, 74%, and 62%, respectively. All patients who began EBRT<or=18 weeks after the start of CMT had their disease controlled locally. Five have mild deficits and 10 have no deficits. A reduced dose of 36-Gy EBRT after delayed GTR may maximize local control while minimizing long-term sequelae for very young children with RMS, but unresectable tumors (e.g., parameningeal) require higher doses. Normal-tissue-sparing techniques such as intensity-modulated radiation therapy and IOHDR are encouraged. Local control may be maximized when EBRT begins <or=18 weeks after initiation of CMT, but further study is warranted. Longer follow-up is required to determine the full extent of late effects.

TU‐EE‐A1‐01: Accuracy of Clinical Dose Delivery in IOHDR Brachytherapy

Purpose: To investigate the accuracy of clinical dose delivery in intra‐operative high dose rate (IOHDR) brachytherapy. Method and Materials: The IOHDR brachytherapy treatments of 10 patients recently treated at our facility were reconstructed. Treatment geometries reflecting each clinical scenario were simulated by a phantom assembly with no added buildup on top of the applicator. EDR2 radiographic film placed at the prescription depth recorded dose distributions for each clinical case. The treatment planning geometry (full scatter surrounding the applicator) was subsequently simulated for each case by adding bolus on top of the applicator and radiographic film was again exposed at the treatment depth. After careful determination of the film's H&amp;D curve, absolute dose distributions in the plane of the prescription depth were evaluated for both scatter environments in each clinical case. Results: For the geometries simulating the treatment planning conditions of full scatter, the average dose measured at the treatment depths was within 2% of the prescription and dose distributions were in excellent agreement with the respective treatment plan. However, for the geometry simulating treatment conditions (no added scattering material above the applicator), the dose at the prescription depth was on average 11% lower (range 8–14%) than prescribed. An analysis of the delivered dose distributions and treatment plans shows a resulting average decrease of 2 mm (range 1.2–2.4 mm) in prescription depth. Conclusion: Dosimetry calculations for IOHDR brachytherapy are typically done with treatment planning systems with dose calculation algorithms that assume an infinite scatter environment around the applicator and target volume. We have shown that this assumption leads to dose delivery errors which result in significant foreshortening of the prescription depth. It may be clinically relevant to correct for these errors by augmenting the scatter environment or, preferably, by appropriately modifying the prescription dose entered into the treatment planning system.

Quantifying IOHDR brachytherapy underdosage resulting from an incomplete scatter environment

Most brachytherapy planning systems are based on a dose calculation algorithm that assumes an infinite scatter environment surrounding the target volume and applicator. Dosimetric errors from this assumption are negligible. However, in intraoperative high-dose-rate brachytherapy (IOHDR) where treatment catheters are typically laid either directly on a tumor bed or within applicators that may have little or no scatter material above them, the lack of scatter from one side of the applicator can result in underdosage during treatment. This study was carried out to investigate the magnitude of this underdosage. IOHDR treatment geometries were simulated using a solid water phantom beneath an applicator with varying amounts of bolus material on the top and sides of the applicator to account for missing tissue. Treatment plans were developed for 3 different treatment surface areas (4 x 4, 7 x 7, 12 x 12 cm(2)), each with prescription points located at 3 distances (0.5 cm, 1.0 cm, and 1.5 cm) from the source dwell positions. Ionization measurements were made with a liquid-filled ionization chamber linear array with a dedicated electrometer and data acquisition system. Measurements showed that the magnitude of the underdosage varies from about 8% to 13% of the prescription dose as the prescription depth is increased from 0.5 cm to 1.5 cm. This treatment error was found to be independent of the irradiated area and strongly dependent on the prescription distance. Furthermore, for a given prescription depth, measurements in planes parallel to an applicator at distances up to 4.0 cm from the applicator plane showed that the dose delivery error is equal in magnitude throughout the target volume. This study demonstrates the magnitude of underdosage in IOHDR treatments delivered in a geometry that may not result in a full scatter environment around the applicator. This implies that the target volume and, specifically, the prescription depth (tumor bed) may get a dose significantly less than prescribed. It might be clinically relevant to correct for this inaccuracy.

Intraoperative single fraction high-dose-rate brachytherapy for head and neck cancers

Purpose To report on the use of single fraction high-dose-rate brachytherapy in delivering localized intraoperative radiation therapy to sites in the head and neck region inaccessible to intraoperative electron beam radiotherapy (IOERT). Methods and materials After maximal surgical resection, 7.5–20 Gy intraoperative high-dose-rate brachytherapy (IOHDR) was delivered to 65 patients using custom-made surface applicators. Results The 1-, 3-, and 5-year local control rates for the entire group were 77%, 69%, and 59%, respectively. The 1-, 3-, and 5-year overall survival rates were 83%, 63%, and 42%, respectively, with a median overall survival of 50 months. There were no major intraoperative or postoperative complications. Conclusions IOHDR can be used to treat selected locally advanced head and neck tumors arising at sites inaccessible to IOERT or at institutions not using IOERT. A prospective multi-institutional study with a larger number of patients treated with IOHDR is needed to firmly establish the efficacy of IOHDR in this population group.

Intraoperative high-dose-rate brachytherapy for paranasal sinus tumors

Purpose Advanced and recurrent tumors of the paranasal sinuses can be difficult to irradiate to high doses with standard external beam radiotherapy (EBRT), conventional brachytherapy, or intraoperative electron beams. We, therefore, explored the role of intraoperative high-dose-rate brachytherapy (IOHDR) as a boost to EBRT in primary tumors or as sole adjuvant treatment in recurrent disease. Methods and materials Between 1992 and 1998, 34 patients with locally advanced tumors arising in the paranasal sinuses were treated with IOHDR after maximal surgical excision. Twenty-seven patients with new primaries underwent gross resection and 10–12.5 Gy IOHDR followed by 45–50 Gy EBRT. Seven previously irradiated (45–63 Gy) patients with recurrent disease were treated with 15–20 Gy of IOHDR alone after gross excision. Local control and overall survival were analyzed using the Kaplan-Meier method and compared using the log–rank test. Results After a mean follow-up of 6 years (range 34–120 months), the 1-, 3-, and 5-year actuarial survival rate was 80%, 62%, and 44%, respectively. The overall local control rate at 1 and 5 years was 75% and 65%, respectively, and distant failure was documented in 44% of patients. Subgroup analysis revealed that the presence of gross disease after surgical resection was the strongest prognosticator, with a 5-year survival and local control rate of 17% and 50%, respectively, compared with 60% and 68%, respectively, for microscopic disease. The local control rates of patients with new primaries were similar to those of patients treated for recurrent disease (63% vs. 71%), probably because gross residual disease occurred only in the group of patients with new primaries. The addition of EBRT to IOHDR increased the 5-year disease-free survival rate from 27% to 44% but had no effect on local control (64% vs. 65%). Conclusion IOHDR can be safely used to deliver a high radiation dose to locally advanced and recurrent tumors in the paranasal sinuses. In an attempt to improve outcome, we are now adding limited-dose EBRT (20–30 Gy) after 17.5 Gy of IOHDR in previously irradiated patients and increasing the EBRT dose for both microscopic (50–54 Gy) and gross residual disease (60–65 Gy) after 15 Gy of IOHDR in previously unirradiated patients. Chemosensitization should also be considered in previously irradiated patients and in those with gross residual disease. Interstitial boosting techniques, which can deliver higher doses at depth, should also be considered in patients with gross residual disease.

Intraoperative high-dose-rate brachytherapy for pediatric solid tumors: a 10-year experience

Purpose To evaluate the efficacy and toxicity of intraoperative high-dose-rate brachytherapy (IOHDR) in the management of pediatric solid tumors. Methods and Materials The records of 66 pediatric patients who underwent IOHDR for a solid tumor from February 1993 through December 2002 were retrospectively reviewed. The median age was 7 years (range 9 months to 24 years). Thirty-five patients (53%) were treated for recurrent disease and 24 (36%) had documented metastatic disease. Twenty-nine patients (44%) received both EBRT and IOHDR. The IOHDR dose was prescribed to a depth of 0.5cm from the surface of a multichannel tissue-equivalent applicator. The median prescription dose was 12 Gy (range, 4–15 Gy). Results After a median follow-up of 12 months, the 2-year actuarial rates of local control and overall survival were 56% and 54%, respectively, with a median survival of 29 months. Post-operative EBRT significantly improved (p = 0.002) 2-year local control (83% v. 29%). Perioperative complications occurred in 8 of 66 patients while late complications occurred in only 3. The actuarial 2-year late complication rate was 12%. Late events that occurred in or near the IOHDR treatment site included small bowel obstruction, broncho-esophageal fistula, and bone growth retardation. Conclusions IOHDR is emerging as an integral part of multimodality therapy for pediatric solid tumors as an adjunct to EBRT for local control. IOHDR alone may not be appropriate in the majority of patients. Subacute toxicities occurred rarely and may be related to the combination of extensive surgery, EBRT, and multi-agent chemotherapy in this population.

Intraoperative high-dose-rate brachytherapy for the treatment of pediatric tumors: the Ohio State University experience

Purpose: To determine whether intraoperative high-dose-rate brachytherapy (IO-HDRBT) can be used to decrease the dose of external beam radiotherapy (EBRT) in the treatment of children with soft-tissue sarcomas and, thereby, reduce morbidity without compromising local control.Methods and Materials: From March 1992 through April 1999, 13 pediatric patients were treated with IO-HDRBT, low-dose EBRT, chemotherapy, and radical surgery at 21 sites that were not amenable to intraoperative electron beam therapy. The IO-HDRBT dose at 5 mm depth was 10 to 12.5 Gy for close margins/microscopic disease at 14 sites and 12.5 to 15 Gy for gross disease at 7 sites. The treatment volumes ranged from 4 to 96 cm3 (mean 27). The EBRT dose was limited to 27–30 Gy in most cases to minimize growth retardation and preserve normal organ function.Results: After a median follow-up of 47 months (range 12–97), 11 patients were alive and without evidence of disease (overall survival rate 85%, 4-year actuarial survival rate 77%). Of the 2 who died, 1 had Stage III pulmonary blastoma with a sacral recurrence; the other had Stage IV undifferentiated synovial sarcoma with a pulmonary recurrence. One local failure occurred in a patient with gross residual disease after incomplete resection for Stage IV pulmonary blastoma. The local control rate was 95%, and morbidity was observed in 3 patients (23%). One patient developed impaired orbital growth with mild ptosis. Another patient required orthopedic pinning of her femoral subcapital epiphysis and construction of a neobladder secondary to urethral obstruction. The third patient required reimplantation of her autotransplanted kidney secondary to chronic urinary tract infection and ureteral reflux.Conclusions: IO-HDRBT allowed for reduction in EBRT without compromising local control or disease-free survival in children with soft-tissue sarcomas. Tumor beds inaccessible to electron beam methods could be satisfactorily encompassed with IO-HDRBT techniques.

Reconstruction and navigation system for intraoperative brachytherapy using the flab technique for colorectal tumor bed irradiation

Purpose: To present the development of a new navigation and reconstruction system based on an electromagnetic free-hand tracker and on CT imaging for treatment planning of intraoperative high-dose-rate brachytherapy (IORT-HDRB) in the sacral region. Our aim is to improve accuracy and to enable individualized treatment planning and dose documentation to be performed for IORT-HDRB using a flab technique. Methods and Materials: The material consists of an electromagnetic 3D tracker system, a PC workstation with Microsoft Windows NT 4.0 operating system, and a recognition program for continuous speech. In addition, we designed an external reference system constructed of titanium and Perspex, which is positioned in the pelvis, and a special digitizer pen for reconstruction of the flab geometry. The flab design incorporates a series of silicon 10-mm-diameter spherical pellets. Measurements were made with a pelvic phantom in order to study the accuracy of the system. The reconstruction results are stored and can be exported via network or floppy to our different treatment planning systems. Results: Our results for the reconstruction of a flab with six catheters and a total of 100 spherical pellets give mean errors in the range (2.5 ± 0.6) mm to (3.5 ± 0.8) mm depending on the positions of the pelvic phantom and transmitter relative to the operation table. These errors are calculated by comparing the reconstruction results of our system with those using a CT-based reconstruction of the flab geometry. For the accuracy of the navigation system for the pelvic phantom, we obtained mean errors in the range (2.2 ± 0.7) mm to (3.1 ± 1.0) mm. Conclusions: The new system we have developed enables navigation and reconstruction within the surgical environment with a clinically acceptable level of accuracy. It offers the possibility of individualized treatment planning and effective documentation of the 3D dose distribution in IORT-HDRB using a flab technique.