Early Clinical Outcomes in Patients of Carcinoma Cervix Treated With Volumetric Modulated Arc Therapy.

Objective Carcinoma cervix is one of the major cancers affecting Indian women. Concurrent chemo-radiotherapy is the standard of care in the treatment of carcinoma cervix. We aimed to study the outcomes and toxicity profile of volumetric modulated arc therapy (VMAT), an advanced modality of radiation delivery when used to treat patients with carcinoma cervix. Materials and methods Patients of carcinoma cervix belonging to FIGO (The International Federation of Gynecology and Obstetrics) stages IB2- IVA were recruited into the study. The patients were treated with VMAT to an EBRT (External Beam Radiation Therapy) dose of 50.4Gy in 28 fractions, which was followed by a brachytherapy schedule of 8Gy for each fraction to point A for three fractions. Toxicities were monitored weekly during the course of treatment and thereafter at every follow-up visit. A response assessment CECT (Contrast Enhanced Computed Tomography) scan was done three months after treatment and the response was recorded using RECIST (Response Evaluation Criteria In Solid Tumors) criteria. Results Sixty-four patients were available for analysis and most of the patients belonged to stage IIB (50.3%) followed by stage IIIB (28.5%). The complete response rate was 90.6% at three months and at a median follow-up of 12 months, the overall survival was 100% and disease-free survival was 89.1%. An analysis of clinically significant toxicities (grade 2 or worse) showed that diarrhea was the most common (20.3%) followed by proctitis (14%) and anemia (9.3%). Conclusion The results of the study established that volumetric modulated arc therapy is an acceptable modality of treatment of carcinoma cervix with an attractive toxicity profile. However, longer follow-ups will provide valuable information regarding the long-term disease control and late toxicities of the treatment.

Image-Guided Brachytherapy a Comparison Between 192Ir and 60Co Sources in Carcinoma Uterine Cervix.

INTRODUCTION: Combination of external beam radiotherapy (EBRT) and High Dose Rate (HDR) brachytherapy (BT) with concurrent chemotherapy (Cisplatin 40mg/m2/weekly) is the standard treatment of approach for the carcinoma of uterine cervix. In this study for image based HDR brachytherapy of intracavitary both 192Ir and 60Co sources were used for dosimetry and the dose distribution compared between point doses and volume doses as per the recommendation of ICRU89 and GEC-ESTRO on 3D image based planning. The dosimetry and clinical outcome will decide decisionmaking on choice of radionuclide for HDR brachytherapy of cervix in addition to economic reason. MATERIALS AND METHODS: The Study conducted for 27 patients of cancer cervix stage IIB or IIIB with vaginal involvement limited to the upper third of vagina. All patients underwent concurrent chemoradiation Cisplatin 40mg/m2 weekly throughout EBRT by 3D conformal therapy 46Gy in 23# followed by two fractions of HDR brachytherapy with 9Gy/1Fr. Post implants 3mm slice selection of pelvic CT scans performed with ring applicator in place followed by T2 weighted paracorpal or paracoronal section of MRI imaging. The solid ring applicator (AL13017000) from library used for applicator reconstruction. Initially all plan calculated with TG-43 formalism using 192Ir radionuclide (Varian, GammaMed HDR Plus source) and then modelled 60Co radionuclide (Eckert < Ziegler BEBIG GmbH, Co0. A86) used for dose computation. ICRU89 recommended points and volumes of targets and OARs evaluated and compared. RESULTS: The study concludes that 60Co based point-A, BICRU and RICRU doses showed a comparable result with that of 192Ir HDR source based dosimetry. The volume based criterion for the target such as GTV, CTVHR, CTVIR for D90, D98, V150%and V200% are all within 5% dose level comparing two sources. CONCLUSION: 60Co a viable alternate to 192Ir by taking into consideration frequency of source exchange and cost reserve with comparable dosimetry.

Impact of GBBS algorithm on post-mastectomy scar boost irradiation of breast using catheter flap.

PURPOSE: Post-mastectomy radiation therapy significantly reduces locoregional recurrence rates, which can be achieved with external beam radiotherapy delivered to chest wall, followed by scar irradiation either by electron or high-dose-rate (HDR) mould brachytherapy. The present study evaluates dosimetric advantage of Acuros® BV, a TG-186 MBDCA, over TG-43 formalism using 192Ir source for HDR brachytherapy in chest wall scar boost using catheter flap. MATERIAL AND METHODS: A total of 25 patients, free of cardiac and pulmonary co-morbidities, who met the inclusion criteria were involved in the study. Catheter flap made of silicon with 20 channels was used to deliver a total dose of 7.5 Gy/3 fx by HDR surface mould brachytherapy to delineated scar volume. Plan was optimized with iterative method to obtain desired results with TG-43 formalism, followed by Acuros® BV (GBBS algorithm) without altering dwell positions or time. The two algorithm plans were analyzed qualitatively and quantitatively with dose-volume histograms. RESULTS: The mean D98% CTV-HDR_evl coverage decreased by 1.16% compared to TG-43, and near-maximum dose decreased by 8.18% (p = 0.000), mean Dmax dose to CTV-HDR_evl, and mean Dmean dose was lesser by 6.25% (p = 0.000) and 10.82% (p = 0.000), respectively, compared to TG-43. Heart D2% showed significant results, whereas Dmedian (cGy) revealed very significant difference. A 5 mm thick skin contour showed statistically significant results (p = 0.000) for V150% and V200%. CONCLUSIONS: The presented data showed how Acuros® BV, algorithm-based calculation in scar boost irradiation of breast, accounting for a mass density of the medium and scatter condition, considered actual dose prediction in a medium.

Malignant soft tissue sarcoma of the shoulder treated by surface mould brachytherapy boost in an adjuvant setting.

PURPOSE: Soft tissue sarcomas of the extremities account for half of all soft tissue sarcomas. Radiotherapy and surgery have been the standard modalities in the treatment of this type of cancer. Brachytherapy can be used as the sole therapy, if the target volume is localized and easily accessible. This work reports three cases of shoulder soft tissue sarcomas with positive deep resected margins, treated with a combination of external beam radiotherapy and surface mould brachytherapy boost technique. MATERIAL AND METHODS: Between January and June 2014, three patients received brachytherapy with sites close to the shoulder, and post-surgery involved deep resected margins. Each mould was made on a base of thermoplastic, over which dental wax was coated and catheters implanted. The target volume was defined as the tissue covering the tumor bed with lateral margins of 2-2.5 cm and depth of 1-1.5 cm. Treatment planning was computed tomography-based and dose prescribed was 85-100% isodose. Treatments has been delivered twice daily, six hours interval, and a review of reactions evaluated. RESULTS: Volume receiving more than 150% of the prescribed dose has been limited to less than 2%, and that above 200% to be inside the mould. Brachytherapy equivalent dose at 2 Gy per fraction (EQD2) of these patients was 24 and 28.6 Gy. Maximum dose to organ at risk (OAR) (2 cc of OAR) ranged between 55-87% of prescribed dose, with a median dose being 80%. All cases had only grade 1 post-radiotherapy skin immediate reactions, which resolved within four weeks. In all patients, no treatment failures were noted at nearly 2-years post-irradiation. CONCLUSIONS: Surface mould brachytherapy in soft tissue sarcomas could be a useful alternative to interstitial brachytherapy, especially where the target volume is superficially extensive with underlying critical structures, and where catheter placement may be difficult, such as the shoulder.

Study of the dosimetric differences between (192)Ir and (60)Co sources of high dose rate brachytherapy for breast interstitial implant.

AIM: The study intends to compare (192)Ir source against the (60)Co source for interstitial breast metal implant in high dose rate brachytherapy. BACKGROUND: Few studies have been reported to compare (60)Co and (192)Ir on HDR brachytherapy in gynaecology and prostate cancer and very few with reference to breast cancer. MATERIALS AND METHODS: Twenty patients who had undergone interstitial template guided breast implant were treated in HDR (192)Ir brachytherapy unit. Plans were generated substituting (60)Co source without changing the dwell positions and optimization. Cumulative dose volume histograms were compared. RESULTS: The reference isodose line enclosing CTV (CTVref) and the 2.34% difference seen in the volume enclosed by the reference isodose line (V ref) between the two isotopes show small but statistically significant difference (p < 0.05). In DHI, no difference was observed in the relative dose between the two sources (p = 0.823). The over dose volume index showed 11% difference. The conformity index showed 2.32% difference compared to (192)Ir (p < 0.05). D mean (%) and D max (%) for the heart, ipsilateral lung, ipsilateral ribs, skin presented very small difference. V 5% and V 10% of the heart shows 25% and 32% difference in dose. D 2cc (%) and D 0.1cc (%) for the contralateral breast, contralateral lung and D 2cc (%) of the skin displayed significant difference (p < 0.05). However, D 0.1cc (%) of the skin indicated no noteworthy difference with p = 0.343. CONCLUSION: Based on the 3D dosimetric analysis of patient plans considered in this study, most of the DVH parameters showed statistically significant differences which can be reduced by treatment planning optimization techniques. (60)Co isotope can be used as a viable alternative because of its long half-life, logistic advantages in procurement, infrequent need of source replacement and disposal of used source.

Dosimetric comparison of Acuros™ BV with AAPM TG43 dose calculation formalism in breast interstitial high-dose-rate brachytherapy with the use of metal catheters.

PURPOSE: Radiotherapy for breast cancer includes different techniques and methods. The purpose of this study is to compare dosimetric calculations using TG-43 dose formalism and Varian Acuros™ BV (GBBS) dose calculation algorithm for interstitial implant of breast using metal catheters in high-dose-rate (HDR) brachytherapy, using (192)Ir. MATERIAL AND METHODS: Twenty patients who were considered for breast conservative surgery (BCS), underwent lumpectomy and axillary dissection. These patients received perioperative interstitial HDR brachytherapy as upfront boost using rigid metal implants. Whole breast irradiation was delivered TG-43 after a gap of two weeks. Standard brachytherapy dose calculation was done by dosimetry. This does not take into account tissue heterogeneity, attenuation and scatter in the metal applicator, and effects of patient boundary. Acuros™ BV is a Grid Based Boltzmann Solver code (GBBS), which takes into consideration all the above, was used to compute dosimetry and the two systems were compared. RESULTS: Comparison of GBBS and TG-43 formalism on interstitial metal catheters shows difference in dose prescribed to CTV and other OARs. While the estimated dose to CTV was only marginally different with the two systems, there is a significant difference in estimated doses of starting from 4 to 53% in the mean value of all parameters analyzed. CONCLUSIONS: TG-43 algorithm seems to significantly overestimate the dose to various volumes of interest; GBBS based dose calculation algorithm has impact on CTV, heart, ipsilateral lung, heart, contralateral breast, skin, and ribs of the ipsilateral breast side; the prescription changes occurred due to effect of metal catheters, inhomogeneities, and scatter conditions.

Role of high dose rate interstitial brachytherapy in early and locally advanced squamous cell carcinoma of buccal mucosa.

BACKGROUND: The study aimed to assess the effect of High Dose Rate (HDR) Interstitial Brachytherapy when used alone or in combination with External Beam Radiotherapy (EBRT), in early and locally advanced squamous cell carcinoma of buccal mucosa. MATERIALS AND METHODS: Thirty three patients with histologically proven squamous cell carcinoma of the buccal mucosa received high dose rate interstitial brachytherapy either as primary treatment or as a boost from November 2008 to April 2013. Stage I patients received interstitial brachytherapy alone to a dose of 38.50 Gy, 3.5 Gy per fraction, twice daily at six hours apart for 11 fractions. Stage II patients received EBRT to a dose of 50 Gy in 25 fractions of two Gy each followed by brachytherapy boost to 21 Gy, 3.5 Gy per fraction, twice daily at six hours apart for six fractions. Stage III patients received the same radiotherapy schedule (i.e., same EBRT & Brachytherapy schedule) and with addition of Injection Cisplatin 70 mg/m(2) in three divided doses every three weeks along with EBRT. RESULTS: Follow up ranged from 12 to 60 months, median follow up was 26 months. Complete response was observed in 28 patients. Five patients had residual disease and were referred for surgical salvage. One patient died of disease progression. Stage I patients had 100% local control, whereas Stage II and Stage III patients had 84.6% and 80% local control respectively. CONCLUSION: HDR Interstitial Brachytherapy used either as a primary treatment modality or as a boost in buccal mucosal cancers provides results comparable to that of surgery, with the advantages of organ preservation, better cosmetic and functional outcomes.