Brachytherapy Techniques Research Articles

Real-time in-vivo dosimetry for DaRT

Diffusing alpha-emitters radiation therapy (DaRT) is a revolutionary brachytherapy technique used to treat solid tumours. Implant seeds are coated with 224Ra which, along its shortlived daughter atoms, emits alpha particles of high linear energy transfer (LET) and of high relative biological efficiency (RBE), creating a tumour-killing dose distribution a few mm wide. Those alpha particles are of energy between 5.67 and 8.78 MeV. DaRT is under investigation in clinical trials, but there currently is no obvious solution for dosimetry aimed at quality assurance of treatment. This study introduces alpha-RAD, a dosimeter based on a metal-oxide-semiconductor (MOS) sensor technology. Alpha-RAD was characterized with 241Am, which emits alpha particles of energy 5.49 MeV. The results showed that alpha-RAD had good linearity with dose, with the signal increasing linearly in the range from 0 to 6.84 Gy. Also, an external bias in the range between 15 and 60 V, applied on the gate of alpha-RAD during irradiation, would optimize sensitivity to alpha particles of energies typical of DaRT. Alpha-RAD, owing to its compactness, can fit into a brachytherapy needle, to be placed next to 224Ra seed implants in the tumour, for real-time in vivo dosimetry.

Metal tube combined with ultrasound-guided accurate interstitial brachytherapy for postoperative pelvic side-wall recurrences of cervical cancers: Technique and outcome

Objective: Our goal was to describe and evaluate the metal tube-assisted ultrasound-guided accurate interstitial brachytherapy technique (TUG-ISBT) and the clinical outcome of a transvaginal treatment without anesthesia modality for the treatment of women with postoperative pelvic sidewall recurrences of cervical cancer.

Intensity modulated Ir-192 brachytherapy using high-Z 3D printed applicators

Gynecologic cancers are often asymmetric, yet current Ir-192 brachytherapy techniques provide only limited radial modulation of the dose. The shielded solutions investigated here solve this by providing the ability to modulate between highly asymmetric and radially symmetric dose distributions at a given location. To find applicator designs that can modulate between full dose and less than 50% dose, at the dimensions of the urethra, a 2D calculation algorithm was developed to narrow down the search space. Two shielding design types were then further investigated using Monte Carlo and Boltzmann-solver dose calculation algorithms. 3D printing techniques using ISO 10993 certified biocompatible plastics and 3D printable tungsten-loaded plastics were tested. It was also found that shadowing effects set by the shape of the shielding cannot be easily modulated out, hence careful design is required. The shielded applicator designs investigated here, allow for reduction of the dose by over 50% at 5 mm from the applicator surface in desired regions, while also allowing radially symmetric dose with isodose line deviations less than 0.5 mm from circular. The shielding designs were also chosen with treatment delivery time in mind. Treatment times for these shielded designs were found to be less than 1.4 times longer than a 6-channel unshielded cylinder for the equivalent fully symmetric dose distribution. The 2D calculation methods developed here provide a simple way to rapidly evaluate shielding designs, while the 3D printing techniques also allow for devices with novel shapes to be rapidly prototyped. Both TOPAS Monte Carlo and Acuros BV calculations show that significant dose shaping and organ at risk sparing can be achieved without significantly compromising the plan in regions that require the full dose.

Iodine-125 interstitial brachytherapy for malignant lacrimal sac tumours: an innovative technique

ObjectivesPrimary malignant tumours of the lacrimal sac are rare, surgery and radiotherapy may induce substantial side effects for patients. Here, this article reports an innovative technique of interstitial brachytherapy developed for the treatment of malignant lacrimal sac tumours.Patients and methodsFour patients (male 3, female 1), with an average age of 52.7 years (range 41–72 years), were individually diagnosed with squamous cell carcinoma, adenocarcinoma, adenoid cystic carcinoma and lymphoma. All patients received Iodine-125 interstitial brachytherapy after surgical resection for malignant lacrimal sac tumours. Visual function examination (vision, intraocular tension, fundus photography, fluorescein angiography, and optical coherence tomography) and CT/MRI/PET-MRI were performed to look for signs of recurrent tumours or metastasis.ResultsFour patients were followed for an average of 28 months (range, 23–37 months). All patients were free from local disease. Their visual function was normal, and CT/MRI did not reveal any tumour recurrence.ConclusionsIodine-125 interstitial brachytherapy can be used as an alternative to wide excision or exenteration of these tumours. There was good local control, reasonable maintenance of vision, and good cosmesis.

Predictors of urinary toxicity with MRI-assisted radiosurgery for low-dose-rate prostate brachytherapy

PurposeMRI-assisted radiosurgery (MARS) is a modern technique for prostate brachytherapy that provides superior soft tissue contrast. The purpose of this analysis was to evaluate treatment planning factors associated with urinary toxicity, particularly damage to the membranous urethra (MUL) and external urethral sphincter (EUS), after MARS. Material and MethodsWe retrospectively reviewed 227 patients treated with MARS. Comparisons were made between several factors including preimplantation length of the MUL and EUS dosimetric characteristics after implantation with longitudinal changes in American Urological Association (AUA) urinary symptom score. ResultsRates of grade 3 urinary incontinence and obstructive urinary symptoms were 4% and 2%. A piecewise mixed univariate model revealed that MUL and V200, V150, V125, and D5 to the EUS were all associated with increased rates of urinary toxicity over time. On univariate logistic regression, MUL >14.2 mm (odds ratio [OR] 2.03 per cm3, 95% confidence interval [CI] 1.10–3.77, p = 0.025), V125 to the EUS (OR 3.21 cm3, 95% CI 1.18–8.71, p = 0.022), and use of the I-125 isotope (OR 3.45, 95% CI 1.55–7.70, p = 0.001) were associated with subacute urinary toxicity (i.e., that occurring at 4–8 months). Optimal dose-constraint limits to the EUS were determined to be V200 < 0.04 cm3 (p = 0.002), V150 < 0.12 cm3 (p = 0.041), V125 < 0.45 cm3 (p = 0.033), D30 < 160 Gy (p = 0.004), and D5 < 218 Gy (p = 0.016). ConclusionsMARS brachytherapy provides detailed anatomic information for treatment planning, implantation, and quality assurance. Overall rates of urinary toxicity are low; however, several dosimetric variables associated with the EUS were found to correlate with urinary toxicity.

Risk of erectile dysfunction after modern radiotherapy for intact prostate cancer.

Erectile dysfunction (ED) is a prevalent side effect of prostate cancer treatment. We hypothesized that the previously reported rates of ED may have improved with the advent of modern technology. The purpose of this project was to evaluate modern external beam radiotherapy and brachytherapy techniques to determine the incidence of radiotherapy (RT) induced ED. A systematic review of the literature published between January 2002 and December 2018 was performed to obtain patient reported rates of ED after definitive external beam radiotherapy, ultrafractionated stereotactic radiotherapy, and brachytherapy (BT) to the prostate in men who were potent prior to RT. Univariate and multivariate analyses of radiation dose, treatment strategy, and length of follow-up were analyzed to ascertain their relationship with RT-induced ED. Of 890 articles reviewed, 24 met inclusion criteria, providing data from 2714 patients. Diminished erectile function status post RT was common and similar across all studies. The median increase in men reporting ED was 17%, 26%, 23%, and 23%, 3DCRT, IMRT, low dose rate BT, and SBRT, respectively, at 2-year median follow-up. ED is a common side effect of RT. Risk of post-RT ED is similar for both LDR brachytherapy and external beam RT with advanced prostate targeting and penile-bulb sparing techniques utilized in modern RT techniques.

Impact of intracavitary brachytherapy technique (2D versus 3D) on outcomes of cervical cancer: asystematic review and meta-analysis.

To perform asystematic review and meta-analysis of the impact of brachytherapy (BT) technique (two-dimensional [2D] or three-dimensional image-guided [3D]) on outcomes of cervical cancer patients. PubMed and EMBASE databases were searched up to April16, 2019, for studies which evaluated the effect of 3D-BT compared to 2D-BT in cervical cancer. Endpoints included cumulative incidence of severe toxicity, locoregional recurrence-free survival (LRRFS), progression-free survival (PFS), and overall survival (OS). Hazard ratios (HRs) were pooled in the meta-analysis using the random-effects model. Six studies of eight cohorts were included in the quantitative synthesis. The pooled HR regarding toxicity was evaluated in five cohorts in three studies, and the HR of 3D-BT compared to 2D-BT was 0.54 (95% confidence interval [CI] 0.37-0.77). All six studies were included for the synthesis for LRRFS, and the pooled HR favors 3D-BT (0.61 [95% CI 0.40-0.93]). For PFS, three studies were included for analysis and 3D-BT was superior to 2D-BT (HR = 0.75 [95% CI 0.59-0.96]). Five studies were included for the pooled HR regarding OS, and pooled HR of 3D-BT compared to 2D-BT was 0.65 (95% CI 0.40-1.06). 3D-BT might reduce severe toxicity and improve LRRFS and PFS in patients with cervical cancer. 3D-BT should be considered for standard management of cervical cancer, and efforts for adopting this procedure in Korea should be pursued.

A novel three-dimensional template combined with MR-guided 125I brachytherapy for recurrent glioblastoma

BackgroundAt present, the treatment of recurrent glioblastoma is extremely challenging. In this study, we used a novel three-dimensional non-coplanar template (3DNPT) combined with open MR to guide 125I seed implantation for recurrent glioblastoma. The aim of this study was to evaluate the feasibility, accuracy, and effectiveness of this technique.MethodsTwenty-four patients of recurrent glioblastoma underwent 3DNPT with open MR-guided 125I brachytherapy from August 2017 to January 2019. Preoperative treatment plan and 3DNPT were made according to enhanced isovoxel T1-weighted MR images. 125I seeds were implanted using 3DNPT and 1.0-T open MR imaging guidance. Dosimetry verification was performed after brachytherapy based on postoperative CT/MR fusion images. Preoperative and postoperative dosimetry parameters of D90, V100, V200, conformity index (CI), external index (EI) were compared. The objective response rate (ORR) at 6 months and 1-year survival rate were calculated. Median overall survival (OS) measured from the date of brachytherapy was estimated by Kaplan-Meier method.ResultsThere were no significant differences between preoperative and postoperative dosimetry parameters of D90, V100, V200, CI, EI (P > 0.05). The ORR at 6 months was 75.0%. The 1-year survival rate was 58.3%. Median OS was 12.9 months. One case of small amount of epidural hemorrhage occurred during the procedure. There were 3 cases of symptomatic brain edema after brachytherapy treatment, including grade three toxicity in 1 case and grade two toxicity in 2 cases. The three patients were treated with corticosteroid for 2 to 4 weeks. The clinical symptoms related to brain edema were significantly alleviated thereafter.Conclusions3DNPT combined with open MR-guided 125I brachytherapy for circumscribed recurrent glioblastoma is feasible, effective, and with low risk of complications. Postoperative dosimetry matched the preoperative treatment plan. The described method can be used as a novel implantation technique for 125I brachytherapy in the treatment of recurrent gliomas.Trial registrationThe study was approved by the Institutional Review Board of Shandong Provincial Hospital Affiliated to Shandong University (NSFC:NO.2017–058), registered 1st July 2017.

Impact of real-time, dose-escalated permanent seed implant brachytherapy in intermediate-risk prostate cancer.

To retrospectively evaluate biochemical control and toxicity in patients who underwent 125I seed brachytherapy (BT) for intermediate-risk prostate cancer (PCa). Between January 2004-December 2014, 395 patients with intermediate-risk PCa underwent 125I BT. Of these, 117 underwent preoperative planning (PP; 145 Gy) and 278 real-time intraoperative preplanning (IoP; 160 Gy). All patients were followed for ≥ 6 months (> 5 years in 48% of patients and > 7 years in 13%). Median follow-up was 59 months. Biochemical relapse-free survival (BRFS) rates at 5 and 8 years were, respectively, 91.7% and 82.1%. By treatment group, the corresponding BRFS rates were 93.5% and 90% for IoP and 89% and 76.8% for PP. The maximum dose to the urethra remained unchanged (217 Gy) despite the dose escalation (from 145 to 160 Gy), without any significant increase in treatment-related toxicity (p = 0.13). Overall toxicity outcomes in the series were excellent, with only 3 cases (0.76%) of grade 3 genitourinary toxicity. The real-time intraoperative planning technique at 160 Gy yields better biochemical controls than the preoperative planning technique at 145 Gy. Dose escalation did not increase urinary toxicity. The excellent results obtained with the IoP BT technique support its use as the first treatment option in this patient population.

The Effect of High Dose Rate Interstitial Implant on Early and Locally Advanced Oral Cavity Cancers: Update and Long-Term Follow-Up Study.

IntroductionBrachytherapy, with or without external beam radiation therapy (EBRT), can be an alternative to surgery for organ preservation in early and locally advanced oral cavity cancers. This study aims to evaluate the effect of high dose rate (HDR) interstitial brachytherapy on early and locally advanced squamous cell carcinoma (SCC) of the oral cavity when used alone or as a boost to EBRT.MethodsA total of 125 patients with histologically proven stage T1-3/N0-1 SCC of the oral cavity were included in the study. A total of 15 patients with stage I disease received an interstitial implant dose of 3,850 cGy at 350 cGy per fraction, two fractions a day. Another 53 patients had stage II, and 57 patients had stage III disease; these patients received EBRT of 50 Gy in 25 fractions along with an HDR brachytherapy boost of 21 Gy in seven fractions of 3 Gy per fraction twice daily. The stage III patients also received concurrent chemotherapy with injections of cisplatin (70 mg/m2) given every three weeks for three days in divided doses. All node-positive patients received a boost to the node of up to 64 Gy by external beam radiation. Disease response rates, five-year disease-free survival rates, and toxicities were analyzed.ResultsThe median follow-up was 60 months. Among the patients, 103 (82.4%) had a complete response, while 22 (17.6%) had residual disease and were referred for surgical salvage. The five-year disease-free survival was 100% in stage I, 83% in stage II, and 77.2% in stage III; 4% of patients developed grade 3 acute skin toxicity and 23.2% developed acute grade 3 mucositis. Eleven patients died during the follow-up period. Two patients died due to myocardial infarction but had achieved a complete tumor response. One patient had pulmonary tuberculosis and died due to fulminant infection after three years of disease-free survival period. One patient developed a second primary in the brain stem that presented with quadriplegia and expired. Seven patients died due to the progression of the initial disease.ConclusionsProper brachytherapy technique and meticulous planning can minimize the toxicity while providing better tumor control and achieve high local control rates. Brachytherapy, with or without EBRT, can be a surrogate to surgery in early oral cavity cancers as it can achieve organ preservation while providing good functional outcomes.

Outcomes analysis of pre-brachytherapy MRI in patients with locally advanced cervical cancer

IntroductionVarious brachytherapy options are available for treating cervical cancer. This study investigated whether pre-brachytherapy magnetic resonance imaging (MRI) findings could help identify the appropriate brachytherapy technique for cervical cancer.MethodsWe retrospectively...

Abstract P6-16-05: Clinical outcomes achieved with brachytherapy vs whole breast irradiation for ductal carcinoma in situ

Abstract Purpose: To compare the locoregional control achieved with whole breast irradiation (WBI) and accelerated partial breast irradiation (APBI) in women with ductal carcinoma in situ (DCIS). Methods: We used an institutional, IRB-approved database to retrospectively identify women with primary DCIS lesions less than 3 cm from 1995 to 2014, who underwent negative-margin breast conserving surgery (BCS) followed by either WBI or APBI. Cox-proportional hazard analysis was performed to estimate risks of in-breast tumor recurrence (IBTR) and regional nodal recurrence (RNR), adjusting for age of patient at diagnosis. Results: Three-hundred and eighty women were identified. Seventy-nine percent received WBI and 21% underwent APBI. Among women receiving WBI, 15.4% received a sequential lumpectomy cavity boost. APBI was delivered via high-dose-rate (HDR) brachytherapy technique, utilizing either a multi-catheter interstitial or single-entry intracavitary approach. The median follow-up time was 6 years for women who received WBI, and 8.9 years for women who received APBI. The actuarial 10-year IBTR rate was 9.0% for WBI and 8.75% for APBI (p = 0.94). The actuarial 10-year isolated regional nodal recurrence (RNR) rate was 0% for WBI and 2.5% for APBI. Among women who received WBI, the 10-year IBTR rate was 10.0% without lumpectomy cavity boost and 6.36% with boost (p = 0.40). Increasing age correlated with a lower risk of recurrence, regardless of treatment modality (p = 0.005). Conclusions: No differences in locoregional control was detected for women with DCIS measuring &amp;lt;3 cm, treated with BCS followed by APBI vs WBI. Citation Format: Katarina T Nguyen, David Francis, Thevaa Chandering, Kelli Pointer, Bethany Anderson. Clinical outcomes achieved with brachytherapy vs whole breast irradiation for ductal carcinoma in situ [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-16-05.

Influence of tumor shape and location in eye plaque brachytherapy dosimetry

PurposeA common treatment planning technique for eye plaque brachytherapy is to model the tumor as an ellipse. For posterior tumors near the optic disc and fovea, this approach may lead to overlap between tumor and the organ at risk (OAR). We hypothesized that a superior plan can be generated by modeling the actual tumor shape. Materials and MethodsForty eye plaque patients with tumors <1 cm from the optic disc and fovea were selected. Two treatment plans were generated for each patient: an elliptical tumor model plan and a true tumor model plan. Dosimetric data were collected for each plan, and Wilcoxon signed-rank tests were used to asses any statistically significant differences. ResultsEquivalent tumor coverage was confirmed between the elliptical and true tumor plans for all patients. Qualitative analysis showed greater dosimetric differences between plans as the distance from the OARs increased from 0 to 2 mm but the largest differences were observed between 2 and 4 mm. Minimal differences between models were seen beyond 4 mm. Statistically significant dosimetric improvements were found for tumors <4 mm from the fovea and <2 mm from the optic disc. ConclusionsIntuitively, accurate modeling of the tumor accounting for irregularities in the shape should result in a more conformal plan and an overall reduction in OAR dose. However, this technique is only beneficial for tumors that are within 4 mm of the fovea or optic disc. An elliptical tumor model allows for an acceptable plan unless the tumor is located posteriorly and has an irregular shape.

Selection Criteria and Clinical Outcomes of Patients With Asymmetrical Cervical Cancer Treated With Various High-dose-rate Brachytherapy Techniques.

We aimed to evaluate the efficacy of high-dose-rate brachytherapy techniques selected according to pre-brachytherapy magnetic resonance imaging (MRI) findings in asymmetrical cervical cancer (ACC). We analyzed 33 ACC patients. Asymmetric tumors were defined as those in which the difference between the distance from the cervical canal to the farthest end of the tumor [long distance (LD)] and the distance from the cervical canal to the contralateral tumor edge [short distance (SD)] is equal to or greater than 2 cm on the basis of MRI prior to treatment. On pre-treatment and pre-brachytherapy MRI, the median LDs were 40 mm and 21 mm, respectively. Patients with LD≥2 cm and LD - SD≥1 cm on pre-brachytherapy MRI received non-conventional intracavitary brachytherapy (ICBT). Sixteen patients (48%) received non-conventional ICBT. There was no significant difference in 3-year local control between the two treatment groups (100% vs. 81.2%, p=0.07); two patients had grade 2 radiation proctitis. Brachytherapy techniques selected according to pre-brachytherapy MRI findings were effective for ACC treatment.

Ring Versus Ovoids and Intracavitary Versus Intracavitary-Interstitial Applicators in Cervical Cancer Brachytherapy: Results From the EMBRACE I Study

The aim of this study was to investigate the influence of brachytherapy technique and applicator type on target dose, isodose surface volumes, and organ-at-risk (OAR) dose. Nine hundred two patients treated with tandem/ovoids (T&O) (n = 299) and tandem/ring (T&R) (n= 603) applicators from 16 EMBRACE centers were analyzed. Patients received external beam radiation therapy and magnetic resonance imaging guided brachytherapy with dose prescription according to departmental practice. Centers were divided into 4 groups, according to applicator/technique: Ovoids and ring centers treating mainly with the intracavitary (IC) technique and ovoids and ring centers treating routinely with the intracavitary/interstitial (IC/IS) technique. V85Gy EQD210, CTVHR D90% (EQD210), and bladder, rectum, sigmoid, and vaginal 5-mm lateral-point doses (EQD23) were evaluated among center groups. Differences between T&O and T&R were tested with multivariable analysis. For similar point A doses, mean CTVHR D90% was 3.3 Gy higher and V85Gy was 23% lower for ring-IC compared with ovoids-IC centers (at median target volumes). Mean bladder/rectum doses (D2cm3 and ICRU-point) were 3.2 to 7.7 Gy smaller and vaginal 5-mm lateral-point was 19.6 Gy higher for ring-IC centers. Routine use of IC/IS technique resulted in increased target dose, whereas V85Gy was stable (T&R) or decreased (T&O); reduced bladder and rectum D2cm3 and bladder ICRU-point by 3.5 to 5.0 Gy for ovoids centers; and similar OAR doses for ring centers. CTVHR D90% was 2.8 Gy higher, bladder D2cm3 4.3 Gy lower, rectovaginal ICRU-point 4.8 Gy lower, and vagina 5-mm lateral-point 22.4 Gy higher for ring-IC/IS versus ovoids-IC/IS centers. The P values were <.002 for all comparisons. Equivalently, significant differences were derived from the multivariable analysis. T&R-IC applicators have better target dose and dose conformity than T&O-IC in this representative patient cohort. IC applicators fail to cover large target volumes, whereas routine application of IC/IS improves target and OAR dose considerably. Patients treated with T&R show a more favorable therapeutic ratio when evaluating target, bladder/rectum doses, and V85Gy. A comprehensive view on technique/applicators should furthermore include practical considerations and clinical outcome.

Implementation of peer-review quality rounds for gynecologic brachytherapy in a high-volume academic center

PurposeWhile peer review is critical for quality and safety in radiotherapy, there are neither formal guidelines nor format examples for brachytherapy (BT) peer review. We report on a gynecologic BT peer-review method implemented at a high-volume academic center. Methods and MaterialsWe analyzed discussions at bimonthly gynecologic BT peer-review rounds between July and December 2018. Rounds consisted of 2–5 attending physicians with gynecologic BT expertise, 1–2 BT physicists, and trainees. Peer-review targets included clinical case review, contours, implant technique, dose/fractionation, and target/organ-at-risk (OAR) dosimetry. The projected/final target and OAR dosimetry were analyzed. Results55 separate implants from 44 patients were reviewed. Implants were mostly reviewed after the first BT fraction (n = 16, 29%) or at another time point during BT (n = 20, 36%). One (2%) implant was presented prospectively. The applicator type and BT technique were reviewed for all implants. Dose/fractionation was evaluated for 46 implants (84%); contours were discussed for 21 (38%). Target and OAR dosimetry were reviewed for 54 (98%) and 28 implants (51%), respectively. Six cases (11%) underwent minor changes to the applicator type to improve target and/or OAR dosimetry. One case (2%) had a major change recommended to the dose/fractionation. ConclusionsGynecologic BT peer review may enhance BT quality by allowing for implant optimization and formal review of challenging cases, ultimately improving medical decision-making and team communication. Peer review should be implemented in centers offering gynecologic BT.

Analysis of clinical utilization of ring applicator for combined intracavitary/interstitial image-guided brachytherapy treatment in Chinese patients with locally advanced cervical cancer.

PurposeTo analyze the results of clinical utilization of ring applicator for combined intracavitary (IC)/interstitial (IS) image-guided brachytherapy (BT) technique in locally advanced cervical cancer (LACC), and to explore the application conditions of IC/IS BT approach with this applicator for Chinese patients.Material and methodsIC/IS BT was performed in total of 95 LACC patients, who already received external beam radiotherapy. In forty-three of these patients, utilization of ring applicator in brachytherapy was done, including IC/IS BT approach with ring applicator for 65 fractions. Clinically optimized IC/IS BT plan with ring applicator (IC/IS treatment) and additionally generated optimized plan without needle use (IC research) were designed, respectively. Dosage differences in target regions and organs at risk (OARs) were analyzed between both the plans. Four planes were selected in the longitudinal direction of uterine cervix and divided the 360° area around the tandem into eight equal sectors. Tumor target features and prescription dose distributions on different planes were described.ResultsThe usage rate of ring applicator with most suitable ring diameter of 26 mm was 45.3% in Chinese cervical cancer patients. The high-risk clinical target volume (HR-CTV) D90/D98 and intermediate-risk CTV (IR-CTV) D90/D98 in IC/IS treatment were significantly higher than IC research. As compared with IC research plan, the D2.0 cm3 of bladder and rectum in IC/IS treatment were significantly lower (p < 0.05). There was no significant difference in D2.0 cm3 of sigmoid and small bowel between two plans. When the target volume was larger than 36 cm3, IC alone had an inadequate coverage of target.ConclusionsNearly half of Chinese patients with LACC could be treated with the ring applicator. The application conditions of IC/IS BT approach with ring applicator for Chinese patients were achieved. Combined IC/IS image-guided BT based on magnetic resonance imaging (MRI) planning is clinically feasible in Chinese patients.

Intracavitary plesiotherapy as boost treatment in a patient of cancer cervix

Purpose: Mold brachytherapy is an age old treatment for superficial tumors. Vaginal mold brachytherapy for gynecological malignancies of vaginal vault and vagina is being practiced in different institutes across the globe. We are reporting the technical aspects of vaginal mold and optimal treatment to the patient. Materials and Methods: This is a case of Carcinoma Cervix International Federation of Gynaecology and Obstetrics st-IIIA(lower one-third vaginal involvement) with residual disease in the anterior wall of lowerd one-third of vagina after the completion of external beam radiotherapy. The patient was reluctant for interstitial implant brachytherapy and hence was planned for vaginal mold brachytherapy with an aim to boost residual tumor. Five stainless steel Implant needles attached to the sorbo from 9'o clock to 3'o clock position with adequate spacing between the needles. Modeling wax, which is nearly tissue equivalent, was used for making mold. The material was molded into a cast cylindrically over the needles and sorbo homogeneously taking care that there were no air gaps. After taking aseptic precautions the cylindrical mold with needles and sorbo was inserted into the vaginal cavity and stabilized with a T-bandage. Computed tomography scan was performed and images were imported to treatment planning system. Clinical target volume was contoured along with organs at risk (bladder and rectum) and geometric optimization was done to obtain proper dwell times and positions where the D90was kept at 100% of the prescribed dose. Conclusion: Vaginal mold brachytherapy may be used as an alternative technique to interstitial implant brachytherapy as a boost treatment in vaginal malignancies. Patient-specific mold brachytherapy technique can be used in the cases where the target volume is superficial and limited to vagina. It is a minimally invasive technique which mimics the dose distribution of interstitial brachytherapy.

A novel 169 Yb-based dynamic-shield intensity modulated brachytherapy delivery system for prostate cancer.

Intensity modulated brachytherapy (IMBT) is a novel high dose rate brachytherapy (HDR BT) technique which incorporates static or dynamic shielding to increase tumor coverage and/or spare healthy tissues. The purpose of this study is to present a novel delivery system (AIM-Brachy) design that can enable dynamic-shield IMBT for prostate cancer. The AIM-Brachy system dynamically controls the rotation of platinum shields, placed within interstitial catheters, which partially collimate the radiation emitted from an 169 Yb source. Conventional HDR BT (10Ci 192 Ir) and IMBT (18Ci 169 Yb) plans were generated for 12 patients using an in-house column generation-based optimizer, coupled to a Geant4-based dose calculation engine, RapidBrachyMC. Treatment plans were normalized to match the same PTV D90 coverage as the clinical plan. Intershield attenuation effects were taken into account. A sensitivity analysis was performed to evaluate the dosimetric impact of systematic longitudinal source positioning errors ( 1mm, 2mm, and 3mm) and rotational errors ( 5 , 10 and 15 ) on clinically relevant parameters (PTV D90 and urethra D10 ). The platinum shield reduced the dose rate on the shielded side at 1cm to 18.1% of the dose rate on the unshielded side. For equal PTV D90 coverage, the urethral D10 was reduced by 13.3% 4.7%, without change to other plan quality indices (PTV V100 , V150, V200 , bladder V75 , rectum V75 , HI, COIN). Delivery times for HDR BT and IMBT were 9.2±1.6min and 18.6±4.0min, respectively. In general, the PTV D90 was more sensitive to source positioning errors than rotational errors, while the urethral D10 was more sensitive to rotational errors than source positioning errors. For a typical range of positioning errors ( 1mm, 5 ), the overall tolerance was <2%. The AIM-Brachy system was proposed to deliver dynamic-shield IMBT for prostate cancer with the potential to create a low dose tunnel within the urethra. The urethra-sparing properties are desirable to minimize the occurrence and severity of urethral strictures or, alternatively, to provide a method for dose escalation.

Brachytherapy with surgical resection as salvage treatment for recurrent high-grade meningiomas: a matched cohort study.

To evaluate surgical resection with brachytherapy placement as a salvage treatment in patients with recurrent high-grade meningioma who exhausted prior external beam treatment options. Single-center retrospective review of our institutional experience of brachytherapy implantation from 2012 to 2018. The primary outcome of the study was progression free survival (PFS). Secondary outcomes included overall survival (OS) and complications. A matched cohort of patients not treated with brachytherapy over the same time period was evaluated as a control group. All patients had received prior radiation treatment and underwent planned gross total resection (GTR) surgery. A total of 27 cases were evaluated. Compared with prior treatment, brachytherapy implantation demonstrated a statistically significant improvement in tumor control [HR 0.316 (0.101 - 0.991), p = 0.034]. PFS-6 and PFS-12 were 92.3% and 84.6%, respectively. Compared with the matched control cohort, brachytherapy treatment demonstrated improved PFS [HR 0.310 (0.103 - 0.933), p = 0.030]. Overall survival was not statistically significantly different between groups [HR 0.381 (0.073 - 1.982), p = 0.227]. Overall postoperative complications were comparable between groups, although there was a higher incidence of radiation necrosis in the brachytherapy cohort. Brachytherapy with planned GTR improved PFS in recurrent high-grade meningioma patients who exhausted prior external beam radiation treatment options. Future improvement of brachytherapy dose delivery methods and techniques may continue to prolong control rates and improve outcomes for this challenging group of patients.