Seema Sharma

Early Clinical Outcomes and Toxicity of Intensity Modulated Versus Conventional Pelvic Radiation Therapy for Locally Advanced Cervix Carcinoma: A Prospective Randomized Study

PURPOSEnTo evaluate the toxicity and clinical outcome in patients with locally advanced cervical cancer (LACC) treated with whole pelvic conventional radiation therapy (WP-CRT) versus intensity modulated radiation therapy (WP-IMRT).nnnMETHODS AND MATERIALSnBetween January 2010 and January 2012, 44 patients with International Federation of Gynecology and Obstetrics (FIGO 2009) stage IIB-IIIB squamous cell carcinoma of the cervix were randomized to receive 50.4 Gy in 28 fractions delivered via either WP-CRT or WP-IMRT with concurrent weekly cisplatin 40 mg/m(2). Acute toxicity was graded according to the Common Terminology Criteria for Adverse Events, version 3.0, and late toxicity was graded according to the Radiation Therapy Oncology Group system. The primary and secondary endpoints were acute gastrointestinal toxicity and disease-free survival, respectively.nnnRESULTSnOf 44 patients, 22 patients received WP-CRT and 22 received WP-IMRT. In the WP-CRT arm, 13 patients had stage IIB disease and 9 had stage IIIB disease; in the IMRT arm, 12 patients had stage IIB disease and 10 had stage IIIB disease. The median follow-up time in the WP-CRT arm was 21.7 months (range, 10.7-37.4 months), and in the WP-IMRT arm it was 21.6 months (range, 7.7-34.4 months). At 27 months, disease-free survival was 79.4% in the WP-CRT group versus 60% in the WP-IMRT group (P=.651), and overall survival was 76% in the WP-CRT group versus 85.7% in the WP-IMRT group (P=.645). Patients in the WP-IMRT arm experienced significantly fewer grade ≥2 acute gastrointestinal toxicities (31.8% vs 63.6%, P=.034) and grade ≥3 gastrointestinal toxicities (4.5% vs 27.3%, P=.047) than did patients receiving WP-CRT and had less chronic gastrointestinal toxicity (13.6% vs 50%, P=.011).nnnCONCLUSIONnWP-IMRT is associated with significantly less toxicity compared with WP-CRT and has a comparable clinical outcome. Further studies with larger sample sizes and longer follow-up times are warranted to justify its use in routine clinical practice.

High-dose-rate interstitial brachytherapy for liver metastases: first study from India

Purpose To study the safety and efficacy of high-dose-rate interstitial brachytherapy (HDRIBT) in patients with liver metastases (LM). Material and methods Between 2009 and 2011, 10 patients with 12 metastatic lesions in the liver were enrolled in this prospective trial. All patients had either refused surgery or found ineligible for surgery due to various factors. Under CT guidance, 16 gauze blind end stainless steel or rigid plastic brachytherapy needle was inserted in the center of lesion through the percutaneous route. Generally, a single interstitial brachytherapy (IBT) needle for lesions up to 3 cm and multiple needles for lesions more than 3 cm in diameter were inserted. Treatment was delivered with a single high-dose-rate (HDR) dose of 20 Gy prescribed to the target. The needles were removed immediately after the treatment. The endpoints of study were acute complications and local control of the disease. Results The median size of the lesion was 3.8 cm (2.7-7.0 cm). The average time for the entire IBT procedure was 65 minutes (50-105 minutes). Median follow up was 9 months (3-17 months). None of the patients had fatal complications. Minor complications like pain, nausea/vomiting, and asymptomatic pleural effusion were observed in 3, 2 and 1 patients, respectively. Local control rate at 12 months was 75%. The 1-year local progression free survival (LPFS) was 33%. Conclusion Although limited by small sample size, the results of our first study from India suggest that HDRIBT is a safe and effective non surgical option for LM.

Comparative Evaluation of Two-dimensional Radiography and Three Dimensional Computed Tomography Based Dose-volume Parameters for High-dose-rate Intracavitary Brachytherapy of Cervical Cancer: A Prospective Study

BACKGROUNDnDosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum.nnnMATERIALS AND METHODSnSixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned . All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning.nnnRESULTSnMean doses received by 100% and 90% of the target volume were 4.24 ± 0.63 and 4.9 ± 0.56 Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were 2.88 ± 0.72, 2.5 ± 0.65 and 2.2 ± 0.57 times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were 1.80 ± 0.5, 1.48 ± 0.41 and 1.35 ± 0.37 times higher than ICRU rectal reference point.nnnCONCLUSIONSnDosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.

Interstitial brachytherapy vs. intensity-modulated radiation therapy for patients with cervical carcinoma not suitable for intracavitary radiation therapy

PURPOSEnInterstitial brachytherapy (IBT) is the standard alternative treatment for patients with cervical carcinoma not suitable for intracavitary radiotherapy. There is an emerging belief that intensity-modulated radiotherapy (IMRT) has the potential to replace IBT. We aimed to compare the dosimetry achieved by IBT and IMRT in such patients.nnnMETHODS AND MATERIALSnThe CT imaging data, previously used for IBT planning of 12xa0patients with cervical carcinoma, were transferred to IMRT planning system to generate parallel IMRT plans. Prescribed dose to the planning target volume (PTV) was 20Gy delivered in 2-weekly high-dose-rate fractions of 10Gy each with IBT (biologically equivalent dose [BED10] 40Gy) and 33Gy/13 fractions/2.5 wk with IMRT (BED10 41Gy). For comparison, dose-volume parameters for target and organs at risk were recorded and expressed in terms of BED10 and BED3, respectively.nnnRESULTSnFor PTV, the mean D95 (dose received by 95% of PTV) was better with IBT (57.16Gy vs. 41.47Gy, p=0.003). The mean conformity index was 0.94 and 0.90 with IBT and IMRT, respectively (p=0.034). IBT delivered significantly reduced doses to 1.0cc (Dmax), 5.0cc (D5 cc), 50% (D50), and 75% (D75) of bladder volume as compared with IMRT. The mean rectal Dmax was significantly better with IBT as compared with IMRT (54.64Gy vs. 62.63Gy, p=0.02).nnnCONCLUSIONSnIBT provides superior PTV coverage and organs at risk sparing to IMRT. Thus, IBT remains the standard treatment for patients with cervical carcinoma unsuitable for intracavitary radiotherapy.

Thermal Analysis of Electron Gun for a Miniature Helix TWT

Thermal analysis of a compact miniature electron guns is essential due to the requirement of high reliability in beam performance. The electron gun for the medium power (CW) helix traveling wave tube (TWT) possesses high dimensional sensitivity due to its miniature size and the requirement of tube to tube matching with reference to their gain and phase. Keeping this in view, a detailed thermal analysis including the determination of temperature profile at various electrodes in the vicinity of cathode particularly of beam forming electrode (BFE), anode etc., and thermal drain through cathode support structure have been carried out using ANSYS package. With this package (I) a cathode support with optimum thermal drain and sufficient holding strength has been optimized and (II) thermal expansion of the electron gun electrodes have been computed in order to evaluate the inter-electrode spacings in the hot condition.

Comparison of high-dose-rate intracavitary brachytherapy dosimetry with and without anesthesia in patients with cervical carcinoma

This study compares the dosimetry of high‐dose‐rate intracavitary brachytherapy (HDR‐ICBT) performed with and without general anesthesia/spinal anesthesia (GA/SA) in patients with cervical carcinoma. We retrospectively retrieved the records of 138 HDR‐ICBT applicator insertions performed in 46 patients: 69 performed with GA/SA (anesthesia group known as AG) in 23 patients, and 69 performed without GA/SA (nonanesthesia group known as NAG) in 23 patients. The intracavitary brachytherapy (ICBT) application was done with central tandem and two vaginal ovoids. For each ICBT plan, a high‐dose‐rate (HDR) dose of 7 Gy was prescribed to point A. From each plan, the doses to Point B right (BR), Point B left (BL), bladder and rectal reference points (Bladderref and Rectalref) were recorded and compared in the two groups. Students t‐test was applied to find out the significance of difference. The two groups were comparable in terms of demography and clinical characteristics. Mean Point BL doses in AG and NAG were 1.89 Gy (27% of Point A dose) and 1.82 Gy (26% of Point A dose), respectively. Mean Point BR doses in AG and NAG were 1.91 Gy (27% of Point A dose) and 1.85 Gy (26% of point A), respectively (p‐value 0.7). The mean dose to Bladderref in AG and NAG was 5.03 Gy and 4.90 Gy, respectively (p‐value 0.6). The mean dose to Rectalref was significantly higher in AG than NAG (5.09 Gy vs. 4.49 Gy, p‐value 0.01). Although based on conventional 2D dosimetry planning, our study has demonstrated that avoiding GA/SA does not result in inferior HDR‐ICBT dosimetry. PACS number: 87.53.Jw, 87.50.cm

Hypofractionated accelerated radiotherapy (HART) with concurrent and adjuvant temozolomide in newly diagnosed glioblastoma: a phase II randomized trial (HART-GBM trial)

IntroductionMaximal safe surgical resection followed by adjuvant chemoradiation has been standard for newly diagnosed glioblastoma multiforme (GBM). Hypofractionated accelerated radiotherapy (HART) has the potential to improve outcome as it reduces the overall treatment time and increases the biological effective dose.MethodsBetween October 2011 and July 2017, a total of 89 newly diagnosed GBM patients were randomized to conventional fractionated radiotherapy (CRT) or HART. Radiotherapy was delivered in all patients with a three-dimensional conformal radiotherapy technique in CRT arm (60xa0Gy in 30 fractions over 6xa0weeks @ 2xa0Gy/per fraction) or simultaneous integrated boost intensity modulated radiotherapy in HART arm (60xa0Gy in 20 fractions over 4xa0weeks @ 3xa0Gy/per fraction to high-risk planning target volume (PTV) and 50xa0Gy in 20 fractions over 4xa0weeks @ 2.5xa0Gy/per fraction to low-risk PTV). The primary endpoint of the trial was overall survival (OS).ResultsAfter a median follow-up of 11.4xa0months (Range: 2.9–42.5xa0months), 26 patients died and 39 patients had progression of the disease. Median OS for the entire cohort was 23.4xa0months. Median OS in the CRT and HART arms were 18.07xa0months (95% CI 14.52-NR) and 25.18xa0months (95% CI 12.89-NR) respectively, pu2009=u20090.3. Median progression free survival (PFS) for the entire cohort was 13.5xa0months (Range: 11.7–15.7xa0months). In multivariate analysis patients younger than 40xa0years of age, patients with a gross total resection of tumor and a mutated IDH-1 had significantly better OS. PFS was significantly better for patients with a gross total resection of tumor and a mutated IDH-1. All patients included in the trial completed the planned course of radiation. Only two patients required hospital admission for features of raised intracranial tension. One patient in the HART arm required treatment interruption.ConclusionHART is comparable to CRT in terms of survival outcome. HART arm had no excess treatment interruption and minimal toxicity. Dose escalation, reduction in overall treatment time, is the advantages with use of HART.

A partially backlogged EPQ model with demand dependent production and non-instantaneous deterioration

The present paper deals with a production inventory system for non-instantaneous deteriorating items with demand dependent production rate. It is assumed that demand rate is exponentially increasing function of time. Shortages are considered and partially backordered at a rate of decreasing function of waiting time for next replenishment. Herein, two cases for life time approach regarding the production stopping time point have been studied separately. The numerical examples have been provided separately to illustrate each case. Finally, sensitivity analysis has also been made to show the behaviour of presented model in each case.

Institutional experience of interstitial brachytherapy for head and neck cancer with a comparison of high- and low dose rate practice.

AIMSnTo describe our institutional experience with high dose rate (HDR) interstitial brachytherapy (IBT) compared with previously reported results on the low dose rate (LDR) practice for head and neck cancer.nnnMATERIALS AND METHODSnEighty-four patients with oral cavity (n=70) or oropharyngeal cancer (n=14) were treated with 192Ir HDR-IBT. Seventy-eight patients had stage I or II tumour. The patients treated with IBT alone (n=42) received 39-42 Gy/10-14 fractions (median=40 Gy/10 fractions). With respect to the combination therapy group (n=42), prescription dose comprised of 12-18 Gy/3-6 fractions (median=15 Gy/5 fractions) for IBT and 40-50 Gy/20-25 fractions (median=50 Gy/25 fractions) for external radiotherapy. Brachytherapy was given as 2 fractions per day 6 hours apart with 4 Gy per fraction for monotherapy and 3 Gy per fraction for combination therapy.nnnRESULTSnFour patients were not evaluable in the analysis of outcome. The primary site relapse rates were 23.8% (10/42) and 68.4% (26/38) in patients treated with IBT alone and combination therapy, respectively (p<0.001). Salvage surgery was performed in 19 patients. The 5-year local control rate was estimated at 62% and the disease-free survival (DFS) rate at 52% for all patients. Local control with respect to T1 and T2 tumours was 84% and 42%, respectively.nnnCONCLUSIONSnOur present series on HDR-IBT and the previous report on LDR-IBT for head and neck cancer demonstrated similar DFS rates at 5 years (52%). The rate of regional failure in node-negative patients was <20% in both of our series. HDR-IBT offers similar results to LDR-IBT for head and neck cancer.

Development of a 30 W (peak) S-band Helix Travelling-wave Tube

The development of a 30 W (peak) S-band helix travelling-wave tube (TWT) for use as a preamplifier in a radar system is described. The salient features of the design include a gridded Pierce electron gun, a slow-wave structure consisting of a wire helix supported by three alumina rods in a metal shell, an isolated collector, and complete ceramic-metal structure of tube envelope.