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The aim of this study was to evaluate the breast dose heterogeneity in CT-based radiotherapy treatment planning and to correlate with breast parameters. Also, the number of slices required for treatment planning in breast cancer by tangential field technique has been assessed by comparing the treatment plans according to International Commission on Radiation Units and Measurement (ICRU) 50 guidelines (1993) for single-slice, three-slice, and multi-slice (3D) planning. Sixty women who underwent isocentric tangential field breast radiotherapy were included in this study. The plans were optimized and analyzed with dose volume histograms. Sixty-three percent of the single-slice plans and 26.7% of the three-slice plans showed poor dose homogeneity as compared to the 3D plans. Dose inhomogeneity correlated better with breast volume (r² = 0.43) than the chest wall separation (r² = 0.37) and breast area product (r² = 0.36). Similarly, breast volume correlated better with breast area product (r² = 0.80) than with chest wall separation (r² = 0.56). Breast volume can be approximated to breast area product from the relation, breast volume = [(breast area product x 8.85) - 120.05]. The results of this study showed that most of the cases require 3D planning for breast cancer. It also showed that patients with large breast are prone to have more dose inhomogeneity with standard tangential field radiotherapy. In centers where 3D planning is not possible due to lack of facilities or workload, three slices-based planning can be performed to approximate the dosimetric advantage of 3D planning. [ABSTRACT FROM AUTHOR]

BACKGROUND: Brain Single Photon Emission Computerised Tomography (SPECT) has been established as a potentially useful tool for the assessment of recurrent brain tumours. Though brain SPECT is exquisitely sensitive in detecting viable tumour tissue in the supratentorial region, its efficacy has not been evaluated till date in case of infratentorial posterior fossa tumours. AIM OF THE STUDY: To evaluate the diagnostic utility of brain SPECT in differentiating recurrence of tumour from post-radiation gliosis in the posterior fossa of the brain. SUBJECTS AND METHODS: Twenty-one patients with primary malignant posterior fossa brain tumour were evaluated by brain SPECT with Tc99m-Tetrofosmin as the tumour-seeking agent. Clinical behaviour of the tumour observed for a minimum period of one year after the SPECT study was taken as the gold standard. STATISTICAL ANALYSIS: The Chi-square test has been used to note the significance of the association between the clinical outcome and the SPECT finding. In addition, the sensitivity and specificity of brain SPECT were also calculated. RESULT: Brain SPECT in 4 patients revealed increased tracer concentration over the primary tumour bed, which was consistent with recurrent tumour. The clinical course was consistent with tumour recurrence in 13 of the 21 patients, which included 3 patients with positive SPECT study and 10 patients with negative SPECT study. Brain SPECT revealed recurrent tumour in 4 patients whereas clinical follow-up suggested recurrence in 13 patients. The clinical course was consistent with radiation necrosis in the remaining 8 patients. In 1 brain SPECT positive patient the clinical course was consistent with post-radiation gliosis. CONCLUSION: This study demonstrates that brain SPECT is not a sensitive diagnostic modality to differentiate recurrent tumour from post-radiation gliosis in the posterior fossa of the brain. [ABSTRACT FROM AUTHOR]

Purpose: Field matching poses challenges in craniospinal irradiation (CSI) as it leads either to underdosage or overdosage in the junctional area. A simple technique for CSI in pediatric patients is proposed. Materials and Methods: Computed tomography scans were performed in the prone position. Two lateral cranial fields and a direct posterior spinal field were planned with a common central axis. Half-beam-blocked cranial fields with zero collimator rotation were used for treating the cranium. A half-beam-blocked field defined with jaws was used to treat the spinal column at an extended sourceto-surface distance. Before treating the patient, matching of the cranial and spinal field junction along the central axis was verified with an extended dose range film. Results and Conclusion: The technique described is simple and easy to implement and can be applied to pediatric patients undergoing CSI. This method has the potential to reduce daily setup time and setup errors. This technique is ideally suitable for patients with spinal fields less than 30 cm. [ABSTRACT FROM AUTHOR]

Purpose: This study was mainly framed to study the difference in tumor volumes as seen on computed tomography (CT) and magnetic resonance (MR) and their significance in planning.Materials and Methods: Twenty-five patients with brain tumor of different diagnoses who underwent stereotactic radiotherapy were included in this study. CT and MR imaging was done for all the patients with 2.5 mm slice thickness. The CT tumor volume and MR tumor volume were measured and compared with each other. The center of mass (CM) of the tumor volume delineated on CT and MR were computed and the shift between the two CMs was determined.Results: The mean and median volume of the tumor as measured from MR scans was 19.67 cc +/- 13.73 and 16.13 cc (range: 3.25 cc-50.37 cc). Similarly, the mean and median volume of the tumor as measured from CT scans was 15.05 cc +/- 10.13 and 11.63 cc (range: 3.0 cc-36.25 cc) respectively. The mean and median CM shift between CT and MR was 5.47 mm and 5.21 mm respectively.Conclusion: The study demonstrates that MR is an indispensable imaging modality in radiotherapy for planning brain tumors. [ABSTRACT FROM AUTHOR]