Purpose: Intensity modulated radiotherapy (IMRT) in the recent past has established itself as a gold standard for organs at risk (OAR) sparing, target coverage and dose conformity. With the advent of a rotational treatment technology such as volumetric modulated arc therapy (VMAT), an inter-comparison is warranted to address the advantages and disadvantages of each technique. Methods: Twenty patients were selected retrospectively from our patient database. Sites included were brain, head and neck, chest wall, and prostate, with five patients for each site. For all the selected patients, both the IMRT and VMAT treatment plans were generated. Plan comparison was done in terms of OAR dose, dose homogeneity index (HI), dose conformity index (CI), target coverage, low isodose volumes, monitor units (MUs), and treatment time. Results: The VMAT showed better sparing of "parotids minus planning target volume (PTV)", spinal cord and head of femur as compared to the IMRT. The lung V40 for VMAT was lower, whereas the lung V10, contralateral lung mean dose, contralateral breast mean dose and mean body dose were lower with IMRT for chest wall cases. Both the VMAT and IMRT achieved comparable HI except for the brain site, where IMRT scored over VMAT. The CI achieved by the IMRT and VMAT were similar except for chest wall cases, whereas the VMAT achieved better dose conformity. The target coverage was comparable with both the plans. The VMAT clearly scored over IMRT in terms of average MUs (486 versus 812 respectively) and average treatment time (2.54 minutes versus 5.54 minutes) per treatment session. Conclusion: The VMAT (RapidArc) has a potential to generate treatment plans for various anatomical sites which are comparable with the corresponding IMRT plans in terms of OAR sparing and plan quality parameters. The VMAT significantly reduces treatment time as compared to the IMRT, thus VMAT can increase the throughput of a busy radiotherapy department.
Case ReportAbstract Angiosarcoma is a rare malignancy of vascular origin. It can affect any part of the body, head and neck region being probably the most common site of diagnosis. We present here a case of Angiosarcoma of face in a 67-year-old elderly gentleman who was treated with RapidArc -volumetric modulated arc therapy (VMAT) for recurrence after surgery, radiotherapy and chemotherapy. As an alternative to Electron Beam Therapy, RapidArc with skin bolus can be considered for large complex shaped targets with irregular surface and tissue inhomogeneity. RapidArc plan can achieve adequate target coverage with acceptable dose homogeneity and conformity.
Original ArticleAbstract Purpose: Tongue is a mobile organ in head and neck region predisposing it for geographic miss during the course of fractionated radiotherapy for tongue malignancy. This study analyses movement of tongue during the course of radiotherapy using volumetric KV-cone beam computed tomography (KV-CBCT) imaging for patients of tongue malignancy treated without using tongue bite. Methods: We analysed 100 KV-cone beam CTs performed on 10 patients with carcinoma of tongue undergoing fractionated radiotherapy. All the patients underwent thermoplastic mask immobilisation and CT simulation. During the course of radiotherapy, all patients underwent volumetric KV-CBCT imaging to assess the movements of tongue. Five arbitrary reference points were used to analyse the movements of tongue in 3-dimensions: 1) Point A: Tip of tongue; 2) Point B: Point over right lateral border, 4 cm posterior to the tip of tongue; 3) Point C: Point over left lateral border, 4 cm posterior to the tip of tongue; 4) Point D: Point over superior most part (dorsum) of tongue, 4 cm posterior to the tip of tongue; 5) Point E: Point over the surface of base of tongue at the level of tip of epiglottis. Results: Mean movements of point A: +0.21 cm (SD: 0.12) and -0.23 cm (SD: 0.14), point B: +0.14 cm (SD: 0.04) and -0.19 cm (SD: 0.1), point C: +0.12 cm (SD: 0.05) and -0.14 cm (SD: 0.06), point D: +0.15 cm (SD: 0.07) and -0.29 cm (SD: 0.22) and point E: +0.23 cm (SD: 0.15) and -0.23 cm (SD: 0.14). Conclusion: Organ movement is one of the great challenges encountered during radiotherapy. Tongue is one such organ in head and neck region. Concept of internal target volume (ITV) margin which takes into account the internal organ movements should be considered for tongue malignancies. ITV to PTV margin will depend on the setup accuracy, immobilization device and imaging modality utilised for setup verification. In an IGRT (Image Guided Radio Therapy) setup, a PTV margin of 0.3 to 0.5 cm from ITV would be safe.
Hypertrophic pulmonary osteoarthropathy is manifested by clubbing and periostitis of bones. We present a very rare documentation of increased F18-sodium fluoride uptake in the distal phalanges of both hands correlating to clubbing of the fingers in a 55-year-old female patient with carcinoma of lung in whom bone positron emission tomography was performed for metastatic work-up.
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