Treatment outcome with low-dose-rate interstitial brachytherapy in early-stage oral tongue cancers

Purpose : Although radical radiotherapy is known to be equally effective for early-stage oral tongue cancers (T1-2 N0) with the added advantage of organ and function preservation, surgery remains the preferred treatment. We present outcome of patients treated with brachytherapy (BT) either radical or boost. Materials and Methods : Fifty-seven patients (T1/T2 31/26) were studied. Seventeen patients (30%) were treated with radical BT (50-67 Gy) while 40 (70%) with external beam radiation therapy (EBRT) + BT (36-56 Gy + 15-38 Gy]. Low-dose-rate (LDR) BT was delivered with 192 Ir wires, using plastic bead technique with varied dose rates (< 60 cGy/h in 29 patients, 60-90 cGy/h in 17, and> 90 cGy/h in 11). Results : The overall local control (LCR) was achieved in 59.7% (34/57) patients. LCR for T1 and T2 was 67.8% and 50%, respectively. A total of 23 patients had failures [local: 20 (T1: 8; T2: 12 patients), node: 5 (T1:2; T2: 3), and local + nodal: 3]. Overall 5-year disease-free survival and overall survival (OAS) were 51% and 67%, respectively and those for T1 and T2 was 64.5/77.4% and 38.5/54% respectively (P = 0.002). All 16 patients were salvaged. Median survival after salvage treatment was 13.5 months (6-100 months). Soft tissue necrosis was observed in 12.3% (7/57) and osteoradionecrosis in two patients. Conclusion : BT, as an integral part of radical radiation therapy in early-stage tongue cancers, appears to be an effective alternative treatment modality with preservation of the organ and function without jeopardizing the outcome

Treatment outcome with low-dose-rate interstitial brachytherapy in early-stage oral tongue cancers

Purpose : Although radical radiotherapy is known to be equally effective for early-stage oral tongue cancers (T1-2 N0) with the added advantage of organ and function preservation, surgery remains the preferred treatment. We present outcome of patients treated with brachytherapy (BT) either radical or boost. Materials and Methods : Fifty-seven patients (T1/T2 31/26) were studied. Seventeen patients (30%) were treated with radical BT (50-67 Gy) while 40 (70%) with external beam radiation therapy (EBRT) + BT (36-56 Gy + 15-38 Gy]. Low-dose-rate (LDR) BT was delivered with 192 Ir wires, using plastic bead technique with varied dose rates (< 60 cGy/h in 29 patients, 60-90 cGy/h in 17, and> 90 cGy/h in 11). Results : The overall local control (LCR) was achieved in 59.7% (34/57) patients. LCR for T1 and T2 was 67.8% and 50%, respectively. A total of 23 patients had failures [local: 20 (T1: 8; T2: 12 patients), node: 5 (T1:2; T2: 3), and local + nodal: 3]. Overall 5-year disease-free survival and overall survival (OAS) were 51% and 67%, respectively and those for T1 and T2 was 64.5/77.4% and 38.5/54% respectively (P = 0.002). All 16 patients were salvaged. Median survival after salvage treatment was 13.5 months (6-100 months). Soft tissue necrosis was observed in 12.3% (7/57) and osteoradionecrosis in two patients. Conclusion : BT, as an integral part of radical radiation therapy in early-stage tongue cancers, appears to be an effective alternative treatment modality with preservation of the organ and function without jeopardizing the outcome

Dose optimization of intra-operative high dose rate interstitial brachytherapy implants for soft tissue sarcoma

Objective: A three dimensional (3D) image-based dosimetric study to quantitatively compare geometric vs. dose-point optimization in combination with graphical optimization for interstitial brachytherapy of soft tissue sarcoma (STS). Materials and Methods: Fifteen consecutive STS patients, treated with intra-operative, interstitial Brachytherapy, were enrolled in this dosimetric study. Treatment plans were generated using dose points situated at the "central plane between the catheters", "between the catheters throughout the implanted volume", at "distances perpendicular to the implant axis" and "on the surface of the target volume" Geometrically optimized plans had dose points defined between the catheters, while dose-point optimized plans had dose points defined at a plane perpendicular to the implant axis and on the target surface. Each plan was graphically optimized and compared using dose volume indices. Results: Target coverage was suboptimal with coverage index (CI = 0.67) when dose points were defined at the central plane while it was superior when the dose points were defined at the target surface (CI=0.93). The coverage of graphically optimized plans (GrO) was similar to non-GrO with dose points defined on surface or perpendicular to the implant axis. A similar pattern was noticed with conformity index (0.61 vs. 0.82). GrO were more conformal and less homogeneous compared to non-GrO. Sum index was superior for dose points defined on the surface of the target and relatively inferior for plans with dose points at other locations (1.35 vs. 1.27). Conclusions: Optimization with dose points defined away from the implant plane and on target results in superior target coverage with optimal values of other indices. GrO offer better target coverage for implants with non-uniform geometry and target volume

Dose optimization of intra-operative high dose rate interstitial brachytherapy implants for soft tissue sarcoma

Objective: A three dimensional (3D) image-based dosimetric study to quantitatively compare geometric vs. dose-point optimization in combination with graphical optimization for interstitial brachytherapy of soft tissue sarcoma (STS). Materials and Methods: Fifteen consecutive STS patients, treated with intra-operative, interstitial Brachytherapy, were enrolled in this dosimetric study. Treatment plans were generated using dose points situated at the "central plane between the catheters", "between the catheters throughout the implanted volume", at "distances perpendicular to the implant axis" and "on the surface of the target volume" Geometrically optimized plans had dose points defined between the catheters, while dose-point optimized plans had dose points defined at a plane perpendicular to the implant axis and on the target surface. Each plan was graphically optimized and compared using dose volume indices. Results: Target coverage was suboptimal with coverage index (CI = 0.67) when dose points were defined at the central plane while it was superior when the dose points were defined at the target surface (CI=0.93). The coverage of graphically optimized plans (GrO) was similar to non-GrO with dose points defined on surface or perpendicular to the implant axis. A similar pattern was noticed with conformity index (0.61 vs. 0.82). GrO were more conformal and less homogeneous compared to non-GrO. Sum index was superior for dose points defined on the surface of the target and relatively inferior for plans with dose points at other locations (1.35 vs. 1.27). Conclusions: Optimization with dose points defined away from the implant plane and on target results in superior target coverage with optimal values of other indices. GrO offer better target coverage for implants with non-uniform geometry and target volume

Dose optimization in gynecological 3D image based interstitial brachytherapy using martinez universal perineal interstitial template (MUPIT) -an institutional experience

The aim of this study was to evaluate the dose optimization in 3D image based gynecological interstitial brachytherapy using Martinez Universal Perineal Interstitial Template (MUPIT). Axial CT image data set of 20 patients of gynecological cancer who underwent external radiotherapy and high dose rate (HDR) interstitial brachytherapy using MUPIT was employed to delineate clinical target volume (CTV) and organs at risk (OARs). Geometrical and graphical optimization were done for optimum CTV coverage and sparing of OARs. Coverage Index (CI), dose homogeneity index (DHI), overdose index (OI), dose non-uniformity ratio (DNR), external volume index (EI), conformity index (COIN) and dose volume parameters recommended by GEC-ESTRO were evaluated. The mean CTV, bladder and rectum volume were 137 ± 47cc, 106 ± 41cc and 50 ± 25cc, respectively. Mean CI, DHI and DNR were 0.86 ± 0.03, 0.69 ± 0.11 and 0.31 ± 0.09, while the mean OI, EI, and COIN were 0.08 ± 0.03, 0.07 ± 0.05 and 0.79 ± 0.05, respectively. The estimated mean CTV D90 was 76 ± 11Gy and D100 was 63 ± 9Gy. The different dosimetric parameters of bladder D2cc, D1cc and D0.1cc were 76 ± 11Gy, 81 ± 14Gy, and 98 ± 21Gy and of rectum/recto-sigmoid were 80 ± 17Gy, 85 ± 13Gy, and 124 ± 37Gy, respectively. Dose optimization yields superior coverage with optimal values of indices. Emerging data on 3D image based brachytherapy with reporting and clinical correlation of DVH parameters outcome is enterprizing and provides definite assistance in improving the quality of brachytherapy implants. DVH parameter for urethra in gynecological implants needs to be defined further

Dosimetric validation of first helical tomotherapy Hi-Art II machine in India

A Helical Tomotherapy (HT) Hi-Art II machine, Hi ART (TomoTherapy, Inc., Madison, WI, USA) was installed at our center in July 2007, and was the first machine in India. Image-guided HT is a new modality for delivering intensity modulated radiotherapy (IMRT). Dosimetric tests done include (a) primary beam alignment (b) secondary beam alignment (c) water tank measurements (profiles and depth doses) (d) dose rate measurements (e) IMRT verification, and (f) Mega voltage Computed Tomography (MVCT) dose. Primary and secondary beam alignment revealed an acceptable linear accelerator (linac) alignment in both X and Y axes. In addition, it was observed that the beam was aligned in the same plane as gantry and the jaws were not twisted with respect to gantry. The rotational beam stability was acceptable. Multi-leaf collimators (MLC) were found to be stable and properly aligned with the radiation plane. The jaw alignment during gantry rotation was satisfactory. Transverse and longitudinal profiles were in good agreement with the “Gold” standard. During IMRT verification, the variation between the measured and calculated dose for a particular plan at the central and off-axis was found to be within 2% and 1mm in position, respectively. The dose delivered during the TomoImage scan was found to be 2.57 cGy. The Helical Tomotherapy system is mechanically stable and found to be acceptable for clinical treatment. It is recommended that the output of the machine should be measured on a daily basis to monitor the fluctuations in output

Setup error analysis in helical tomotherapy based image-guided radiation therapy treatments

The adequacy of setup margins for various sites in patients treated with helical tomotherapy was investigated. A total of 102 patients were investigated. The breakdown of the patients were as follows: Twenty-five patients each in brain, head and neck (H and N), and pelvis, while 12 patients in lung and 15 in craniospinal irradiation (CSI). Patients were immobilized on the institutional protocol. Altogether 2686 megavoltage computed tomography images were analyzed with 672, 747, 622, 333, and 312 fractions, respectively, from brain, H and N, pelvis, lung, and CSI. Overall systematic and random errors were calculated in three translational and three rotational directions. Setup margins were evaluated using van Herk formula. The calculated margins were compared with the margins in the clinical use for various directions and sites. We found that the clinical isotropic margin of 3 mm was adequate for brain patients. However, in the longitudinal direction it was found to be out of margin by 0.7 mm. In H and N, the calculated margins were well within the isotropic margin of 5 mm which is in clinical use. In pelvis, the calculated margin was within the limits, 8.3 mm versus 10 mm only in longitudinal direction, however, in vertical and lateral directions the calculated margins were out of clinical margins 11 mm versus 10 mm, and 8.7 mm versus 7.0, mm respectively. In lung, all the calculated margins were well within the margins used clinically. In CSI, the variation was found in the middle spine in the longitudinal direction. The clinical margins used in our hospital are adequate enough for sites H and N, lung, and brain, however, for CSI and pelvis the margins were found to be out of clinical margins