Amebic Infection of the Female Genital Tract: A Report of Three Cases.

Amebiasis is a common protozoan disease with a worldwide distribution. It is endemic in tropical developing countries, and cases are being detected in subtropical countries as well. It usually presents with intestinal manifestations. An extraintestinal manifestation of this disease, amebic vaginitis and amebic cervicitis, is rare and often misinterpreted clinically as vaginal and cervical carcinoma because of its overall ulcerated and necrotic appearance. Awareness of this rare manifestation is important for preventing unnecessary interventions and for effectively managing the patients with antiamebic treatment. Herewith, we report three cases of amebic vulvovaginitis and cervicitis in elderly women clinically masquerading as carcinomas.

Small field dosimetry and analysis of flattening filter free beams in true beam system.

AIM OF STUDY: The purpose of this study was to report the dosimetric characteristics of the small fields in flattening filter free (FFF) beams (output measurements, profile analysis, surface dose and consistency) generated by medical linear accelerator and its variation with respect to flattened beams (FB). MATERIALS AND METHODS: Surface doses were obtained for field sizes 1 × 1-40 × 40 cm(2). Field width and penumbra were analyzed for field sizes 1 × 1-40 × 40 cm(2). To take output factors for small fields, diode and micro chamber were used and data was taken at a source-to-surface distance (SSD) and extended SSD. Consistency checked for the dosimetric data for 1 year. RESULTS: Surface doses were higher in FFF compared with FB up to 20 × 20 cm(2) field size. Measured field sizes were slightly lesser in FFF and penumbra values were increased with respect to field size in both FB and FFF. For small fields, diode values have shown more promising results than micro chamber. Small field output measurements at nominal SSD and extended SSD were well in agreement with each other. FFF beams showed good data consistency in 1 year duration. CONCLUSION: Small field dosimetry, surface dose, profile analysis and consistency of FFF beams in FFF photon beams were derived and data shown good consistency during 1 year duration.

Comparative dosimetric evaluation of three-dimensional conformal and stereotactic radiotherapy for treatment of intracranial tumors.

AIMS: To evaluate the dosimetric profile among three-dimensional conformal radiotherapy (3D-CRT) and stereotactic radiotherapy (SRT) for the treatment of intracranial tumors. MATERIALS AND METHODS: Seventeen patients with intra cranial tumors of benign nature or low malignant potential were enrolled and planned for SRT as well as 3D-CRT. Dosimetric comparison between these two plans was done considering the following parameters: Target coverage, conformity index, and heterogeneity index. RESULTS: The dosimetric parameters of the 3D-CRT plans were a little inferior compared with those for the SRT plans. The difference between mean target coverage, mean conformity index and mean heterogeneity index for 3D-CRT and SRT plans was highly significant at P < 0.001 (t = 7.74), P < 0.001 (t = 5.52), and P < 0.01 (t = 3.15) respectively. CONCLUSION: SRT is a very efficient treatment option for intracranial tumors, in view of better target coverage and conformality compared with 3D-CRT.

Chest wall radiotherapy with volumetric modulated arcs and the potential role of flattening filter free photon beams.

PURPOSE: The goal of the work was to assess the role of RapidArc treatments in chest wall irradiation after mastectomy and determine the potential benefit of flattening filter free beams. METHODS AND MATERIAL: Planning CT scans of 10 women requiring post-mastectomy chest wall radiotherapy were included in the study. A dose of 50 Gy in 2 Gy fractions was prescribed. Organs at risk (OARs) delineated were heart, lungs, contralateral breast, and spinal cord. Dose-volume metrics were defined to quantify the quality of concurrent treatment plans assessing target coverage and sparing of OARs. Plans were designed for conformal 3D therapy (3DCRT) or for RapidArc with double partial arcs (RA). RapidArc plans were optimized for both conventional beams as well as for unflattened beams (RAF). The goal for this planning effort was to cover 100% of the planning target volume (PTV) with ≥ 90% of the prescribed dose and to minimize the volume inside the PTV receiving > 105% of the dose. The mean ipsilateral lung dose was required to be lower than 15 Gy and V(20 Gy) < 22%. Contralateral organ irradiation was required to be kept as low as possible. RESULTS: All techniques met planning objectives for PTV and for lung (3DCRT marginally failed for V(20 Gy)). RA plans showed superiority compared to 3DCRT in the medium to high dose region for the ipsilateral lung. Heart irradiation was minimized by RAF plans with ~4.5 Gy and ~15 Gy reduction in maximum dose compared to RA and 3DCRT, respectively. RAF resulted in superior plans compared to RA with respect to contralateral breast and lung with a reduction of ~1.7 Gy and 1.0 Gy in the respective mean doses. CONCLUSION: RapidArc treatment resulted in acceptable plan quality with superior ipsilateral tissue sparing compared to traditional techniques. Flattening filter free beams, recently made available for clinical use, might provide further healthy tissue sparing, particularly in contralateral organs, suggesting their applicability for large and complex targets.

Volumetric modulated arc-based hypofractionated stereotactic radiotherapy for the treatment of selected intracranial arteriovenous malformations: dosimetric report and early clinical experience.

PURPOSE: To evaluate, with a dosimetric and clinical feasibility study, RapidArc (a volumetric modulated arc technique) for hypofractionated stereotactic radiotherapy treatment of large arteriovenous malformations (AVMs). METHODS AND MATERIALS: Nine patients were subject to multimodality imaging (magnetic resonance, computed tomography, and digital subtraction angiography) to determine nidus and target volumes, as well as involved organs at risk (optical structures, inner ear, brain stem). Plans for multiple intensity-modulated arcs with a single isocenter were optimized for a fractionation of 25 Gy in 5 fractions. All plans were optimized for 6-MV photon beams. Dose-volume histograms were analyzed to assess plan quality. Delivery parameters were reported to appraise technical features of RapidArc, and pretreatment quality assurance measurements were carried out to report on quality of delivery. RESULTS: Average size of AVM nidus was 26.2 cm(3), and RapidArc plans provided complete target coverage with minimal overdosage (V(100%) = 100% and V(110%) < 1%) and excellent homogeneity (<6%). Organs at risk were highly spared. The D(1%) to chiasm, eyes, lenses, optic nerves, and brainstem (mean ± SD) was 6.4 ± 8.3, 1.9 ± 3.8, 2.3 ± 2.2, 0.7 ± 0.9, 4.4 ± 7.2, 12.2 ± 9.6 Gy, respectively. Conformity index (CI(95%)) was 2.2 ± 0.1. The number of monitor units per gray was 277 ± 45, total beam-on time was 2.5 ± 0.3 min. Planning vs. delivery γ pass rate was 98.3% ± 0.9%. None of the patients developed acute toxicity. With a median follow-up of 9 months, 3 patients presented with deterioration of symptoms and were found to have postradiation changes but responded symptomatically to steroids. These patients continue to do well on follow-up. One patient developed headache and seizures, which was attributed to intracranial bleed, confirmed on imaging. CONCLUSION: Hypofractionated stereotactic radiotherapy can be successfully delivered using the RapidArc form of volumetric arc technology for intracranial AVMs. The quality of delivery and calculated parameters are in agreement with each other and are in line with published reports for other sites.

QA of intensity-modulated beams using dynamic MLC log files.

To evaluate the utility of Dynalog file information for planar dose verification in IMRT QA, a program is developed to convert Dynalog file data to DMLC field files. For this study, five predefined fluencies are planned and delivered using Varian, Eclipse 3D planning system and 6MV photon beam of Varian, Clinac DMX linear accelerator. To measure planar dose distribution, Kodak, EDR2 films are exposed in similar setup as planning setup. Dynalog files are recorded for each delivery and converted into DMLC field files using in-house program. Delivered dose distributions are calculated using DMLC field files from Dynalog files. Planned, Measured and Delivered dose distributions are compared using gamma evaluation in Scanditronix, Omni Pro IMRT software. The Planned and Delivered planar dose distributions agree within 2% dose difference and 2 mm DTA. Measured dose distributions agree within 4% dose difference and 4 mm DTA with Planned dose distribution. Our results show Dynalog file as a promising tool for dynamic IMRT QA.