Tejinder Kataria

Homogeneity Index: An objective tool for assessment of conformal radiation treatments

Homogeneity Index (HI) is an objective tool to analyz the uniformity of dose distribution in the target volume. Various formulae have been described in literature for its calculation but there is paucity of data regarding the ideal formula and the factors affecting this index. This study was undertaken to analyze HI in our patients using various formulae and to find out the co-relation between HI and prescribed dose, target volume and target location. A retrospective review of 99 patients was performed. HI was calculated using five different formulae (A-E). The patients were divided in five groups each, based on prescribed dose, target volume and target location and mean HI of each group was analysed to find the co-relation between these factors and HI. When there were multiple target volumes the primary target volume was studied. The statistical calculation was done using SPSS version 16.0. Ninety nine patients were found evaluable with 75 males and 24 females. Ninety five patients were treated with radical intent and four with palliative intent. The sites treated were head and neck (46.4%), Pelvis (17.1%), brain (15.1%), abdomen (12.1%), and thorax (6.1%). The mean prescribed dose was 4304 cGy (centiGray) and the mean target volume was 476.2 cc. The mean value of HI was 1.21, 2.08, 30.13, 21.51 and 1.27 with different formulae. There was considerable agreement between HI calculated using various formulae specially the formulae considering prescribed dose (C, D). On statistical analysis, there was no significant co-relation between the location and volume of target but there was a trend toward better HI with increasing prescribed dose. Future studies with more number of patients can confirm our results.

Dosimetric comparison between Volumetric Modulated Arc Therapy (VMAT) vs Intensity Modulated Radiation Therapy (IMRT) for radiotherapy of mid esophageal carcinoma

AIMS Dosimetric comparison of VMAT with IMRT in middle third esophageal cancer for planning target volume (PTV) and organs at risk (OAR). MATERIALS AND METHODS Ten patients in various stages from I‒III were inducted in the neo-adjuvant chemoradiation protocol for this study. The prescribed dose was 4500 cGy in 25 fractions. Both VMAT and IMRT plan were generated in all cases and Dose Volume Histogram (DVH) comparative analysis was performed for PTV and OAR. Paired t-test was used for statistical analysis. RESULTS The PTV Dmean and D95 in IMRT and VMAT plan were 4566.6±50.6 cGy vs 4462.8±81.8 cGy (P=0.1) and 4379.8±50.6 cGy Vs 4424.3±109.8 cGy (P=0.1), respectively. The CI and HI for PTV in IMRT vs VMAT plans were 0.96±0.02 vs 0.97±0.01 (P=0.4) and 10.58±3.07 vs 9.45±2.42 (P=0.2), respectively. Lung doses for VMAT vs IMRT were 4.19 vs 2.59% (P=0.03) for V35-7.63 vs 4.76% (P=0.01) for V30-13.6 vs 9.98% (P=0.01) for V25-24.77 vs 18.57% (P=0.04) for V20-46.5 vs 34.73% (P=0.002) for V15. The Mean Lung Dose (MLD) was reduced by VMAT technique compared to IMRT; 1524.6±308.37 cGy and 1353±186.32 cGy (P=0.012). There was no change in Dmax to spinal cord in both the techniques. There was a dose reduction by VMAT compared to IMRT to the heart but it was statistically insignificant; V35-6.75% vs 5.55% (P=0.223); V30-12.3% vs 10.91% (P=0.352); V25-21.81% vs 20.16% (P=0.459); V20-38.11% vs 32.88% (P=0.070); V15-61.05% vs 54.2% (P=0.10). CONCLUSION VMAT can be a better option in treating mid esophageal carcinoma as compared to IMRT. The VMAT plans resulted in equivalent or superior dose distribution with a reduction in the dose to lung and heart.

Chemoradiation in elderly patients with head and neck cancers: a single institution experience ☆,☆☆

AIMS To evaluate the efficacy and toxicity of concurrent chemoradiation in patients with head and neck cancers aged 65 and older. MATERIALS AND METHODS Thirty-two elderly patients were treated with radical chemoradiation. Twenty-six (81.3%) out of thirty-two patients had stage III-IV disease. Twenty-nine (90.6%) patients received concurrent weekly cisplatin or carboplatin, 3 (9.4%) patients received concurrent cetuximab or nimotuzumab. Total dose of radiotherapy ranged from 66Gy to 70Gy. RESULTS Twenty-nine patients (90.6%) completed at least 5cycles of concurrent chemotherapy. Twenty-four (77.6%) patients achieved complete response. Fourteen (45.2%) patients experienced grade 3 mucositis. None of our patients developed grade 3 or above hematological toxicity. Loco-regional control and overall survival at 2year were 71.6% and 88.9%, respectively. CONCLUSIONS Chemoradiation in elderly patients with high precision radiotherapy is a feasible option.

Synchronous malignant vagal paraganglioma with contralateral carotid body paraganglioma treated by radiation therapy

Paragangliomas are rare tumors and very few cases of malignant vagal paraganglioma with synchronous carotid body paraganglioma have been reported. We report a case of a 20-year old male who presented with slow growing bilateral neck masses of eight years duration. He had symptoms of dysphagia to solids, occasional mouth breathing and hoarseness of voice. Fine needle aspiration cytology (FNAC) performed where he lived showed a sinus histiocytosis and he was administered anti-tubercular treatment for six months without any improvement in his symptoms. His physical examination revealed pulsatile, soft to firm, non-tender swellings over the anterolateral neck confined to the upper-mid jugulo-diagastric region on both sides. Direct laryngoscopy examination revealed a bulge on the posterior pharyngeal wall and another over the right lateral pharyngeal wall. Magnetic resonance imaging (MRI), 99mTc-labeled octreotide scan and angiography diagnosed the swellings as carotid body paraganglioma, stage III on the right side with left-sided vagal malignant paraganglioma. Surgery was ruled out as a high morbidity with additional risk to life was expected due to the highly vascular nature of the tumor. The patient was treated with radiation therapy by image guided radiation to a dose of 5040cGy in 28 fractions. At a follow-up at 16 months, the tumors have regressed bilaterally and the patient can take solids with ease.

Quantification of coronary artery motion and internal risk volume from ECG gated radiotherapy planning scans

BACKGROUND Radiotherapy for carcinoma of breast and thoracic structures involves inadvertent radiation to heart and coronary arteries (CA). Coronary artery stenosis in high radiation dose segments has been documented. Cardiac and respiratory motion induced displacement of CA and internal risk volume (IRV) margin remains inadequately quantified. MATERIAL AND METHODS Twenty cases of carcinoma breast, lung and lung metastasis were enrolled in this study. ECG gated intravenous contrast enhanced computed tomography (CECT) scans were performed in inspiratory breath hold (IBH) and expiratory breath hold (EBH). The images were segregated into inspiratory systole (IS), inspiratory diastole (ID), expiratory systole (ES) and expiratory diastole (ED) sets. Left anterior descending (LAD), limited segment of LAD close to chest wall (short LAD), right coronary artery (RCA), Left circumflex artery (LCX) and left ventricle (LV) were delineated in all four sets. Mean displacements in systole versus diastole and inspiration versus expiration were calculated in three co-ordinates [anterio-posterior (Z), left-right (X) and cranio-caudal (Y)]. RESULTS Mean of displacement (mm) between systole and diastole (IS versus ID; and ES versus ED) in X, Y, Z co-ordinates were: LAD 3.0(±1.6), 2.8(±1.5), 3.6(±2.0); Short-LAD 3.0(±1.1), 0.8(±0.4), 2.4(±0.6); LV 2.4(±1.6), 1.7(±1), 5.0(±1.5); LCX 4.9(±1.6), 2.9(±1.3), 5.1(±1.9); RCA 6.6(±2.2), 3.6(±2.1), 5.9(±2.2). Mean displacement between inspiration and expiration (IS versus ES; and ID versus ED) in X, Y, Z axes were: LAD 3.3(±1.5), 8.0(±3.4), 3.8(±1.8); Short-LAD 2.7(±1), 12.2(±4.4), 3.3(±1.5); LV 2.9(±1.4), 9.8(±3.3), 4.7(±1.9); LCX 2.9(±.8), 9.7(±3.2), 6.2(±2.5); RCA 2.6(±1.3), 7.6(±2.5), 3.8(±1.7). CONCLUSION Radial (RM), cranio-caudal margin (CC) of 7mm, 4mm in breath-hold radiotherapy whereas RM, CC of 7mm, 13mm respectively in free breath radiotherapy will cover the range of motions of CA, LV and can be recommended as IRV for these structures.

Incidental radiation to axilla in early breast cancer treated with intensity modulated tangents and comparison with conventional and 3D conformal tangents.

PURPOSE To analyze incidental radiation doses to minimally dissected axilla with Intensity modulated radiotherapy (IMRT), 3D conformal radiotherapy (3DCRT) and standard tangents (ST). METHODS & MATERIALS We prospectively evaluated incidental radiation to axilla in fifty cases of early breast cancer treated with breast conservation surgery with sentinel node biopsy alone followed by whole breast irradiation with IMRT. Three plans were devised for each CT dataset, comprising ST, 3DCRT and IMRT tangents. Doses to axillary nodal levels I, II and III were evaluated for mean dose, V95, V90, V80 and V50. Comparisons were made using ANOVA. RESULTS The mean doses delivered to axilla by the three techniques (IMRT, 3DCRT, ST) were: 78% (range 67-90, SD ± 5.2%), 80% (63-95, ±7.5%) and 87% (73-98, ±4.8%) for level I (IMRT vs ST; p = 0.037); 70% (46-89, ±12.4%), 72% (34-93, ±15.5%) and 65% (29-87, ±11.8%) for level II; and 51% (28-76, ±11.1%), 53% (19-86, ±13.7%) and 41% (6-72, ±10.6%) for level III, respectively. V90 values (volume receiving 90% of dose) for the three techniques were 49% (43-53, ±2.7%), 57% (51-65, ±3.1%) and 73% (65-80, ±3.4%) for level I (IMRT vs. ST; p = 0.029); 35% (26-42, ±4.7%), 41% (33-50, ±4.2%) and 25% (17-36, ±4.5%) for level II (IMRT vs ST; p = 0.068); and 15% (9-22, ±3.4%), 16% (10-24, ±3.7%) and 8 (5-12, ±3.1%) for level III (IMRT vs ST; p = 0.039), respectively. CONCLUSION Axillary levels I and II (lower axilla) receive substantial amount of incidental radiation doses with all the three techniques; however, conformal techniques (IMRT, 3DCRT) deliver significantly lesser incidental radiation to lower axilla than ST technique.

Set-up uncertainties: online correction with X-ray volume imaging.

AIM To determine interfractional three-dimensional set-up errors using X-ray volumetric imaging (XVI). MATERIALS AND METHODS Between December 2007 and August 2009, 125 patients were taken up for image-guided radiotherapy using online XVI. After matching of reference and acquired volume view images, set-up errors in three translation directions were recorded and corrected online before treatment each day. Mean displacements, population systematic (Σ), and random (σ) errors were calculated and analyzed using SPSS (v16) software. Optimum clinical target volume (CTV) to planning target volume (PTV) margin was calculated using Van Herks (2.5Σ + 0.7 σ) and Strooms (2Σ + 0.7 σ) formula. RESULTS Patients were grouped in 4 cohorts, namely brain, head and neck, thorax, and abdomen-pelvis. The mean vector displacement recorded were 0.18 cm, 0.15 cm, 0.36 cm, and 0.35 cm for brain, head and neck, thorax, and abdomen-pelvis, respectively. Analysis of individual mean set-up errors revealed good agreement with the proposed 0.3 cm isotropic margins for brain and 0.5 cm isotropic margins for head-neck. Similarly, 0.5 cm circumferential and 1 cm craniocaudal proposed margins were in agreement with thorax and abdomen-pelvic cases. CONCLUSION The calculated mean displacements were well within CTV-PTV margin estimates of Van Herk (90% population coverage to minimum 95% prescribed dose) and Stroom (99% target volume coverage by 95% prescribed dose). Employing these individualized margins in a particular cohort ensure comparable target coverage as described in literature, which is further improved if XVI-aided set-up error detection and correction is used before treatment.

Analysis of direct clinical consequences of MLC positional errors in volumetric-modulated arc therapy using 3D dosimetry system.

In advanced, intensity‐modulated external radiotherapy facility, the multileaf collimator has a decisive role in the beam modulation by creating multiple segments or dynamically varying field shapes to deliver a uniform dose distribution to the target with maximum sparing of normal tissues. The position of each MLC leaf has become more critical for intensity‐modulated delivery (step‐and‐shoot IMRT, dynamic IMRT, and VMAT) compared to 3D CRT, where it defines only field boundaries. We analyzed the impact of the MLC positional errors on the dose distribution for volumetric‐modulated arc therapy, using a 3D dosimetry system. A total of 15 VMAT cases, five each for brain, head and neck, and prostate cases, were retrospectively selected for the study. All the plans were generated in Monaco 3.0.0v TPS (Elekta Corporation, Atlanta, GA) and delivered using Elekta Synergy linear accelerator. Systematic errors of +1,+0.5,+0.3,0,−1,−0.5,−0.3 mm were introduced in the MLC bank of the linear accelerator and the impact on the dose distribution of VMAT delivery was measured using the COMPASS 3D dosimetry system. All the plans were created using single modulated arcs and the dose calculation was performed using a Monte Carlo algorithm in a grid size of 3 mm. The clinical endpoints D95%,D50%,D2%, and Dmax,D20%, D50% were taken for the evaluation of the target and critical organs doses, respectively. A significant dosimetric effect was found for many cases even with 0.5 mm of MLC positional errors. The average change of dose D95% to PTV for ±1 mm,±0.5 mm, and ±0.3 mm was 5.15%, 2.58%, and 0.96% for brain cases; 7.19%, 3.67%, and 1.56% for head and neck cases; and 8.39%, 4.5%, and 1.86% for prostate cases, respectively. The average deviation of dose Dmax was 5.4%, 2.8%, and 0.83% for brainstem in brain cases; 8.2%, 4.4%, and 1.9% for spinal cord in H&N; and 10.8%, 6.2%, and 2.1% for rectum in prostate cases, respectively. The average changes in dose followed a linear relationship with the amount of MLC positional error, as can be expected. MLC positional errors beyond ±0.3 mm showed a significant influence on the intensity‐modulated dose distributions. It is, therefore, recommended to have a cautious MLC calibration procedure to sufficiently meet the accuracy in dose delivery. PACS number: 87.56

Malignant obstructive jaundice - brachytherapy as a tool for palliation

Purpose Malignant obstructive jaundice (MOJ) is relieved by stenting via endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography and biliary drainage (PTCD). Stent occlusion rates of 30-45% have been reported in literature due to tumor ingrowth or overgrowth. We prospectively evaluated the feasibility and the role of intraluminal brachytherapy (ILBT) in preventing stent blockage in patients with MOJ after PTCD and stenting. Material and methods Twelve patients with MOJ who underwent PTCD followed by self expanding metallic stent (SEMS) placement were prospectively enrolled in this study. Written informed consent was obtained. Intraluminal brachytherapy was done once patient was stable and serum bilirubin was less than 2 mg% or 50% of baseline value. On the day of ILBT, 6 French brachytherapy catheters were placed across malignant stricture under fluoroscopic guidance with placement of the tip 1 cm distal to stricture. A dose of 10 to 14 Gy was delivered at 1 cm from central axis of the source. Suitable patients also received external beam radiotherapy (EBRT) with weekly concurrent chemotherapy. Results All patients tolerated the procedure well with minimal acute and late toxicities. Duodenal ulceration was observed in 1 patient. At a mean follow up of 10.25 months (5-24 months), stents were patent in 10/12 subjects and stent patency duration of 9.8 months (5-22) was reported. Conclusions Intraluminal brachytherapy post PTCD is feasible and effective in preventing stent occlusion with minimal acute and late toxicities.

Parotid metastasis from carcinoma urinary bladder treated with CyberKnife-based stereotactic body radiotherapy: case report and review of literature

Abstract Metastasestotheparotidregionarerelativelyinfrequentandoriginateprimarilyfromheadandneckcancer.Metastases of an infraclavicular origin are uncommon. Moreover, metastasis from the carcinoma of urinarybladder (CUB) to any part of the head and neck, including parotid gland, is rare. Surgery and chemotherapyare usually offered. We report a case of solitary parotid metastasis from CUB, who was successfully treatedwith stereotactic body radiotherapy (SBRT) using CyberKnife. SBRT is a safe alternative in cases unwilling/unfit for surgery. Keywords: carcinoma urinarybladder;CyberKnife;parotid metastasis; stereotactic body radiotherapyINTRODUCTIONMetastases to the parotid region are relativelyinfrequent andoriginate primarilyfrom head andneck cancer. 1 Metastases of an infraclavicularorigin are uncommon. 2 Moreover, metastasisfromthecarcinomaofurinarybladder(CUB)toanypart of the head and neck, including parotid gland,is rare. 3 Surgery and chemotherapy are usuallyoffered.Thisreportdescribesacaseofsolitaryparotidmetastasis from CUB, who was successfully treatedwith stereotactic body radiotherapy (SBRT) usingCyberKnife. To the best of our knowledge, this isthe first documented case of parotid metastasis fromtransitional cell CUB treated by SBRT.CASE HISTORYA 79-year-old gentleman was operated for CUBin December 2011 and the tumour was staged aspT4pN0cM0 after radical cystectomy. He wasfree from disease recurrence on routine cysto-scopy and [