Ashu Abhishek

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.

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 [

PO-0883: Quantification of Duodenum motion: analysis from respiratory phase guided radiotherapy planning scan

Material and Methods: We studied 12 healthy volunteers (4 males), with a mean age of 33 y, mean height of 172 cm, mean weight of 63 kg and a mean vital capacity of 3.2 L. Each attempted to perform three 1-minute BHs in end-inhale (completely inflated lungs), deep-inhale (lung volume of ~70%), deep-exhale (lung volume of ~30%) and end-exhale (completely deflated lungs). During BH, we used a 3T MRI to dynamically (1.7 Hz) acquire a thick (8 mm) high resolution (0.9×0.9 mm2) 2D coronal slice including both the pancreatic head and the diaphragm. For each BH, the motion (i.e. displacement in all successive images relative to the first image) of the pancreatic head and of the diaphragm in the inferior-superior (IS) direction was determined using a 2D image correlation algorithm. The Wilcoxon signed-rank test was used to test the differences in maximum displacement during BH between the different BH types. To investigate the correlation between the intra-BH motion of the pancreas and of the diaphragm, we determined the Pearson correlation coefficient (r). As the achieved BH duration varied, only the data acquired during the first 30 seconds of each BH were included in our analysis.

SU-F-T-611: Critical Analysis and Efficacy of Linac Based (Beam Modulator) and Cyberknife Treatment Plans for Acoustic Neuroma/schwannoma

PURPOSE To study the critical analysis and efficacy of Linac and Cyberknife (CK) treatment plans for acoustic neuroma/schwannoma. METHODS Twelve of acoustic neuroma/schwannoma patients were taken for these study that. Treatment plans were generated in Multiplan treatment planning system (TPS) for CK using 5,7.5 and 10mm diameter collimators. Target volumes were in the range of 0.280 cc to 9.256 cc. Prescription dose (Rx) ranges from 1150cGy to 1950cGy delivered over 1 to 3 Fractions. For same patients stereotactic Volumetric modulated arc plans were generated using Elekta Linac with MLC thickness of 4mm in Monaco TPS. Appropriate calculation algorithms and grid size were used with same Rx and organ at risk (OAR) constrains for both Linac and CK plans. Treatment plans were developed to achieve at least 95% of the target volume to receive the Rx. The dosimetric indices such as conformity index (CI), coverage, OAR dose and volume receiving 50% of Rx (V50%) were used to evaluate the plans. RESULTS Target volumes ranges from 0.280 cc to 3.5cc shows the CI of 1.16±0.109 and 1.53±0.360 for cyberknife and Linac plans respectively. For small volume targets, the OARs were well spared in CK plans. There are no significant differences in CI and OAR doses were observed between CK and Linac plans that have the target volume >3.5 cc. Perhaps the V50% were lesser in CK plans, and found to be 12.8± 8.4 and 22.8 ± 15.0 for CK and Linac respectively. CONCLUSION The analysis shows the importance of collimator size for small volume targets. The target volumes >3.5 cc can be treated in Linac as comparable with CK. For targets <3.5cc CK plans showed superior plan quality with better CI and OAR sparing than the Linac based plans. Further studies may require evaluating the clinical advantage of CK robotic system.

32 portal vein thrombus irradiation-an alternative in inoperable hepatocellular carcinoma.

Background: Portal vein tumor thrombosis (PVTT), in a case of hepatocellular carcinoma (HCC), is considered poor risk and has been reported to be associated with unfavorable outcomes to the established treatment regimens like surgical resection or TACE (transarterial chemoembolization). Radiotherapy (RT) has shown survival benefits and promises to be a valid salvage therapy in such cases. Aim: To review and establish the role of RT in advanced HCC with portal venous thrombosis. Materials and Method: Literature was reviewed for the role of radiotherapy in PVTT along with the case selection criteria, technique, expected benefits, and possible side effects of the treatment. Discussion: Definitive treatment strategy is not established for PVTT in advanced HCC. With 34–84% incidence, PVT cannot be overlooked and demands alternative approaches. Results of surgery in such cases are dismal and palliative chemotherapy (TACE) may increase the risk of ischemic events. In such cases, radiotherapy has been widely reported to have an objective response rate of 37.5–57.9%, with a median survival time of 6.7–10.7 months. Post PVTTRT, re-canalization may be achieved in 60–75% cases and re-considered for TACE/primary management with acceptable outcomes. Therefore, RT is a promising salvage alternative in PVTT cases not fit for conventional treatment modalities. Medanta Experience: We recently treated a 54-year-old gentleman, diagnosed to have PVTT with HCC, with 60 Gy in 20 Fr by a volumetric modulated arc therapy (VMAT) using respiratory motion management. He tolerated the therapy well and evaluation of CT scans 2 months postRT showed necrosis at tumor thrombus site. He has been re-started on oral chemotherapy and is on close follow-up.