Commissioning and quality assurance of HalcyonTM 2.0 linear accelerator.

BACKGROUND: Varian Medical Systems has introduced a new medical linear accelerator called HalcyonTM 2.0, which is based on the ring delivery system (RDS). It is a true IGRT machine having 6MV FFF photon energy. In addition to the planar and MV-CBCT imaging techniques it also has an option of ultra-fast kV-iCBCT which enhances the image reconstruction and improves the visualization of soft tissue. The field portals are shaped by a unique dual layer MLC with special stacked and staggered design which enables high modulation with low radiation leakage. Recently, we have commissioned our first Halcyon 2.0 machine. The aim of this work was to systematically investigate various parameters of a newly installed HalcyonTM 2.0 linear accelerator. MATERIALS AND METHODS: Detailed measurements were conducted as per various guidelines. Also, the measurements were performed to fulfil the national regulatory requirements. Commissioning data of Halcyon 6 MV-FFF beam was performed in a water tank. For absolute measurements, a 0.6-cc waterproof Farmer chamber and electrometer were used. All relative measurements (PDDs, in-line, cross-line and angular profiles) were performed with 0.0125 cc point chamber. RESULTS: All the tests were within the acceptable limit. Measured data were compared with factory data as well as the existing medical linear accelerator of the same category. The obtained results were quite satisfactory. CONCLUSIONS: This study summarizes the commissioning experience with Halcyon linear accelerator. Evaluation of mechanical, radiation safety and dosimetric parameters were performed. The obtained parameters were well below the specified tolerance limits.

Diffuse cavernous haemangioma of colon: magnetic resonance imaging features. Report of two cases.

Large bowel haemangiomas are rare but can cause significant morbidity. The clinical features are non-specific, and misdiagnosis is very common. Non-invasive imaging is very useful in the diagnosis and management of this condition. Magnetic resonance imaging surpasses all other imaging modalities, as it is most specific and depicts the extent of the lesion accurately. Two cases of cavernous haemangioma of the rectum are presented highlighting the MRI features.

Comparison of graded compression ultrasonography and unenhanced spiral computed tomography in the diagnosis of acute appendicitis.

INTRODUCTION: To compare the accuracy of graded compression ultrasonography (US) and unenhanced spiral computed tomography (CT) in the diagnosis of acute appendicitis. METHODS: This prospective study comprised 58 consecutive patients with high clinical suspicion of acute appendicitis. After careful clinical assessment and laboratory investigations, all the patients were independently evaluated by graded compression US followed by unenhanced spiral CT, in order to establish the diagnosis. CT was performed from the level of the third lumbar vertebral body to the pubic symphysis, and no patient was given oral, rectal or intravenous contrast agents. The results were compared with operative findings and clinical follow-up. RESULTS: Out of the 58 patients evaluated, surgical confirmation was obtained in 52 patients and the remaining six patients were managed conservatively. Statistical analysis was based on the 52 patients who were surgically confirmed. 48 of the operated patients had evidence of appendicitis and four patients had negative findings. In our study, 90 percent of patients were adults and the following results were more applicable to the adult age group. Analysis of the data for US and CT, respectively, revealed a sensitivity of 67.3 percent versus 95.8 percent, specificity of 100 percent versus 75 percent, accuracy of 71.2 percent versus 90.3 percent, positive predictive value of 100 percent versus 97.8 percent, and negative predictive value of 15.8 percent versus 60 percent. Out of the operated patients, four patients did not have acute appendicitis and alternative diagnosis was suggested by US and CT in one patient. Of the six patients managed conservatively, an alternative diagnosis was reached both by US and CT in two patients. CONCLUSION: We conclude that unenhanced spiral CT is more sensitive than US in detecting appendicitis, especially in adult patients.

A pancreaticographic study of malnutrition-related diabetes mellitus.

Pancreatic involvement is considered to be the hallmark of malnutrition-related diabetes mellitus (MRDM). Of the 2 subgroups of the disease, fibrocalculous pancreatic diabetes (FCPD) is characterized by pancreatic calcification. The nature of pancreatic abnormalities in MRDM have not been studied extensively in Indian patients. The present study was designed to compare pancreatic abnormalities (exocrine and endocrine) including endoscopic retrograde pancreaticography in patients with FCPD and protein deficient pancreatic diabetes (PDPD), in relation to controls. Ten patients each of FCPD and PDPD were studied with regard to clinical features, biochemical exocrine and endocrine pancreatic responses, C-peptide response, islet cell antibody, and pancreatographic changes. Five normal pancreatograms were taken as control. Clinical and biochemical features in patient with FCPD and PDPD were as follows: pain in 8 and 2 patients, respectively; the mean duration of diabetes was similar in both groups (62.28 +/- 71.92 months V. 72 +/- 50.9 months); and faecal fat excretion and insulin requirements were comparable in both groups. The main pancreatic duct was dilated in 6 of 10 patient with FCPD and only 1 of 10 with PDPD on ultrasonography. On pancreatography the duct was dilated in 9 of 10 patients with FCPD and only 1 of 10 patients with PDPD. The number of side branches was reduced in all cases with MRDM; in those with FCPD, these were stunted and dilated while in PDPD side branches are thin and spastic. We conclude that pancreatic ductal changes involving the main duct and side branches are more frequent in patients with FCPD as compared to those with PDPD.

Laparoscopy assisted hemi-colectomy for ileo-caecal tuberculosis.

Laparoscopy assisted hemicolectomy for ileo-caecal tuberculosis is being evaluated the world over. Several procedures are performed laparoscopically, including the laparoscopic hemicolectomy, for benign and malignant diseases. Abdominal tuberculosis is one of the commonest causes of intestinal obstruction in India. We have evaluated the role of laparoscopic resection of ileocaecal tuberculosis and successfully performed the procedure in five patients. The clinical profiles of patients and operative procedure are discussed in this article with a brief review of the literature.

Blunt abdominal trauma with delayed rupture of splenic haematoma in a haemophiliac patient.

A 13-year-old haemophilia A patient presented with pain in the abdomen, 4 days after a blunt abdominal trauma. The computed tomography scan of the abdomen showed a large splenic haematoma. The patient was initially managed with factor VIII replacement therapy, but 4 weeks later he had a delayed rupture of the splenic haematoma with haemoperitoneum and shock. An elective splenectomy under factor VIII therapy was successfully performed.

Cysticercosis of the optic nerve.

Cysticercosis of the optic nerve has been reported only twice in the literature. A case of optic nerve cysticercosis in a 50-year-old woman with atypical optic neuritis is reported. Computerized tomography showed a thickened left optic nerve with a ring-enhancing lesion containing an eccentric nodule. An enzyme-linked immunosorbent assay test for cysticercosis further established the diagnosis. The patient was treated with oral prednisolone and albendazole, with no improvement in vision.

Optic nerve cysticercosis: imaging findings.

We present the imaging findings of retrobulbar optic nerve cysticercosis in a 50-year-old woman with a 6-month history of vision loss. Contrast-enhanced CT revealed an approximately 7-mm ring-enhancing cyst with a mural nodule located in the anterior portion of the left optic nerve. A contrast-enhanced MR imaging study revealed a cystic lesion with peripheral enhancement of the mural nodule. Sonography showed a cystic mass with a focal area of increased echogenicity corresponding to the mural nodule.

Proptosis with orbital soft tissue and bone changes and unilateral papilloedema: unusual presentation of POEMS syndrome.

POEMS syndrome is a rare manifestation comprising of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes. Orbital involvement in this syndrome is rare and manifestation with proptosis, even rarer. The imaging features in Poems syndrome and rarity of various features in our case are being highlighted here.

Is protein-deficient diabetes mellitus a pancreatitis?

BACKGROUND: Malnutrition-related diabetes mellitus is a distinct clinical entity subdivided into protein-deficient diabetes mellitus (PDDM) and fibrocalculus pancreatic diabetes (FCPD). Whereas FCPD has obvious pancreatitis manifested by pancreatic duct calculi, the evidence for involvement of the pancreas in PDDM is limited to the presence of ketosis-resistant hyperglycaemia. METHODS: We studied 10 patients with PDDM biochemically and radiologically. Endoscopic retrograde cholangiopancreatography was performed to determine if they had any evidence of chronic pancreatitis. RESULTS: Their mean faecal chymotrypsin level was low (13.2+/-5.72 microg/g), as was their basal c-peptide value (0.35+/-0.15 mmol/L). Islet cell antibodies were not detected in any of these patients. Ultrasound examination revealed pancreatic atrophy. In two patients, however, the pancreas was bulky. The ERCP showed generalized thinning of the pancreatic duct, measuring 2.4+/-0.06mm in the head, 2.01+/-0.08 mm in the body and 1.02 +/- 0.03 mm in tail region; side branches were seen but they were too sparse and thin. CONCLUSIONS: The significance of these changes is not clear, but they may represent an ongoing pancreatic disease and may, indeed, be the earliest changes of chronic pancreatitis.

Magnetic resonance evaluation of idiopathic scoliosis: a prospective study.

The objective of the present study was to determine the incidence of unsuspected intraspinal pathology and to assess the value of atypical clinical features as predictors of these intraspinal pathologies, in patients with idiopathic scoliosis. Twenty-five consecutive patients (13 boys, 12 girls) with idiopathic scoliosis were prospectively evaluated with MRI. Magnetic resonance imaging detected intraspinal pathology in seven patients (28%), which included syringohydromyelia with Chiari I malformation (n = 5), and syringomyelia and dumb-bell neurofibromas in one patient each, respectively. Dural ectasia was also present in five patients. Atypical features, described in the literature as pointers to intraspinal pathologies such as the age < 11 years at presentation, presence of pain, hyperkyphosis, severe curves and the presence of the left thoracic or thoracolumbar curves, were seen to be equally distributed between the two groups (those with and without intraspinal pathologies), thus raising doubts about the importance of these features.

Intrabiliary rupture of hepatic hydatid cyst--imaging features.

Intrabiliary rupture leading to biliary obstruction is a rare but serious presentation of hepatic echinococcosis. Four such cases are presented. Imaging studies including sonography, computed tomography and/or cholangiography, done in all patients led to a definite preoperative diagnosis which was later confirmed at surgery. Biliary tree dilatation was detected in three out of four patients, hydatid contents were seen in three patients and definite cysto-biliary communication was documented in two.

Orbital hydatid cysts: sonographic and CT appearance.

Two cases of unilateral proptosis due to orbital hydatid cysts were evaluated by ultrasound and computed tomography. Image morphology of this rare disease is presented.

Biliary strictures on ERCP: a study in northern India.

Case records of 82 patients with biliary stricture diagnosed on endoscopic retrograde cholangiopancreatography (ERCP) during a 7-years period (1983-89) were analysed for its aetiology, clinical presentation, laboratory abnormalities and radiological characteristics. The aetiology was found to be benign in 59 and malignant in 23 patients. Forty seven percent of all strictures were post cholecystectomy strictures (PCS). Presence of mucosal irregularity and incomplete stricture were commoner with malignancy. Malignant biliary strictures (MBS) were commonly seen in males, occurred at older age, had short history, had higher alkaline phosphtase and serum bilirubin values when compared to patients with benign biliary strictures (BBS).