Purpose: To report a single-institution experience of intensity-modulated radiotherapy (IMRT) and RapidArc treatment plans for the patients treated with low grade mucoepidermoid carcinoma (MEC) of the salivary gland while sparing the organs at risk (OARs) within tolerance limits. Material and Methods: Twenty-five patients with MEC were selected to develop and analyse the treatment plans using both of the techniques. Dose distributions were calculated using Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA). Plans were generated to deliver the dose of 6000 cGy in 30 fractions. For IMRT, seven angle plans were used and for RapidArc, two half arcs were used with the same 6 MV photon beam. Quality of treatment plans was evaluated by using parameters such as, coverage, conformity index (CI), homogeneity index (HI), gradient index (GI), unified dosimetry index (UDI), dose volume histogram, delivery time and OARs sparing for IMRT and RapidArc plans. Results: The analysis revealed that IMRT and RapidArc coverages are 0·90 and 0·94, respectively; CIs are 1·15 and 1·10, respectively; HIs are 1·12 and 1·07, respectively; GIs are 0·94 and 0·98, respectively. Average UDI values for RapidArc and IMRT are 1·09 and 1·11, respectively. Integral dose comparison shows better OAR sparing for RapidArc. RapidArc plans have the shorter beam on time (45%) in comparison with IMRT plans. Conclusion: Planning constraints were achieved in both techniques. However, RapidArc showed better quality treatment plan, OARs sparing and shorter delivery time as compared to IMRT.

Purpose: The study of clinical effectiveness of deep-inspirational breath-hold (DIBH) in left breast cancer radiotherapy (RT) was aimed at focusing on dosimetry and organs at risk (OARs) evaluation. A retrospective study was conducted to assess the heart and ipsilateral lung V30 for DIBH technique and to compare with free breathing (FB) technique. Clinical data shows that by increasing the inhalation amplitude value (cm), the maximum heart distance decreases in the treatment field. Materials and Methods: Thirty left-sided breast and chest wall patients were CT scanned on 4DCT with DIBH. These patients were chosen for the DIBH technique with the ability to hold their breath for more than 20 seconds. Radiotherapy of these patients was planned using field-in-field planning technique, and OAR doses were observed using the institutionally specified DIBH protocol. Results: The mean heart dose was less than 3Gy. Whereas V2Gy and V10Gy were less than 30% and 5%. The mean ipsilateral lung dose was 7.59 Gy. Ipsilateral lung V30 was less than 25% with ±10% margins. It is found that by increasing the inhaling amplitude (cm) heart involvement in the tangential treatment field decreases. Conclusion: DIBH is an easy and highly efficient treatment technique for reducing the mean dose of the heart and V30 of ipsilateral lung. The maximum heart distance decreases as the baseline of inhalation increases due to heart doses.

Purpose:The main objective of this study is to assure the quality of cervical cancer treatment plans using an electronic portal imaging device (EPID) in RapidArc techniques.Materials and Methods:Fifteen cases of cervical cancer patients undergoing RapidArc technique were selected to evaluate the quality assurance (QA) of their treatment. The computed tomography (CT) of each patient was obtained with 3-mm-slice thickness and transferred to the Eclipse treatment planning system. The prescribed dose (PD) of 50·4 Gy with 1·8 Gy per fraction to planning target volume (PTV) was used for each patient. The aim of treatment planning was to achieve 95% of PD to cover 97%, and dose to the PTV should not receive 105% of the PD. All RapidArc plans were created using the AAA algorithm and treated on Varian DHX using 6 MV photon beam, with two full arcs. Gamma analysis was used to evaluate the quality of the treatment plans with accepting criteria of 95% at 3%/3 mm.Results:In this study, maximum and average gamma values were 2·53 ± 0·409 and 0·195 ± 0·059 showing very small deviation and indicating the smaller difference between both predicted and portal doses. Gamma Area changes from > 0·8 to > 1·2. SD increased to 5·4% and mean standard error increased to 4·67%.Conclusion:On the basis of these outcomes, we can summarise that the EPID is a useful tool for QA in standardising and evaluating RapidArc treatment plans of cervical cancer in routine clinical practice.