Aims: Intensity-modulated radiotherapy (IMRT) is increasingly used in the treatment delivery of chemoradiotherapy in anal cancer with the ability to reduce toxicity. We report on 4 year outcomes since the introduction of IMRT and identify the most predictive bowel organ at risk that correlates with acute diarrhoea. Materials and methods: Fifty-eight patients receiving definitive chemoradiotherapy for squamous or basaloid cell anal carcinoma (T1-4NanyM0) were reviewed. Fifty-four per cent of patients had stage III disease and most (79%) were treated with a dose of 54 Gy in 30 fractions. Patient acute gastrointestinal toxicity was recorded using Common Terminology Criteria of Adverse Events (CTCAE) diarrhoea grading. Four different methods of bowel were re-contoured for each patient and correlated with acute diarrhoea. Locoregional control and overall survival were analysed. Results: CTCAE grade 3 or more diarrhoea occurred in 11/58 patients (19%). Seven patients did not complete treatment; 10 patients (17%) required a treatment break of 3 or more days. 'Bowel cavity' was the best predictor of acute grade 3 toxicity using volume (P = 0.002) or volume to bowel cavity in 5 Gy bins (V5-V50Gy); P < 0.05. Bowel cavity V30Gy <= 300 cm(3) predicts a 6% grade 3 diarrhoea risk versus > 300 cm(3) predicts a 42% risk. Four year progression-free survival was 84% (95% confidence interval 73-92%) and overall survival was 88% (95% confidence interval 75-95%). Conclusion: Chemoradiation using IMRT provides excellent local control and acceptable acute gastrointestinal toxicity. Bowel cavity is the most sensitive predictor for grade 3 versus grade 0-2 diarrhoea, with any volume receiving 5-50 Gy discriminatory. (C) 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

It is well documented that the prostate bed is highly susceptible to inter-fraction motion leading to larger treatment planning margins to account for daily treatment set up uncertainties when matching to bony anatomy. The use of fiducial markers in the prostate bed has significantly improved accuracy of treatment delivery. This pilot study aims to investigate the role and benefits of radio-opaque hydrogel tissue marker in the treatment of post prostatectomy intensity modulated radiation therapy (IMRT). Twenty patients treated with IMRT to a dose of 70.2Gy in 39 fractions between Jan 2016 to Jan 2017 were included in this study. All patients underwent transperineal injection of hydrogel tissue marker at the level of vesico-urethral anastomosis and cystoscopically into the posterior bladder wall. Instructions for bladder and bowel preparation to be followed during CT simulation and daily treatments were provided to the patients. Daily on-line cone beam CT matching to the hydrogel tissue marker was performed prior to each treatment and off-sets relative to skin tattoos were recorded in 3 directions: left-right (LR); superior-inferior (SI) and anterio-posterior (AP). Daily image registration using bony matching was then assessed off-line and off-sets relative to skin tattoos were again recorded. The mean and standard deviation of the differences between the hydrogel tissue markers and bony off-sets were calculated for all fractions for each patient; then the overall mean and systematic (Σ) and random errors (σ) for the entire cohort were calculated. The planning target volume (PTV) margin required for bony matching was estimated using van Herk's formula of 2.5Σ + 0.7σ, which is designed to ensure a minimum dose of 95% of prescribed dose to the clinical target volume (CTV) in 90% of patients. These margins are relative to the hydrogel tissue markers which are assumed to be in the target tissue. A total of 1520 images were analysed. The overall mean shift differences between the hydrogel tissue markers and bones for the entire cohort were LR: 0.13mm (Σ 0.38mm, σ 1.35mm); SI: 0.92mm (Σ 1.40mm, σ 2.50mm) and AP: 0.40mm (Σ 1.98mm, σ 3.18mm). The calculated PTV margins for bony matching relative to hydrogel tissue markers were 1.90mm in LR, 5.25mm in SI and 7.17mm AP directions. Prostate bed motion is independent of pelvic bone anatomy and soft tissue matching has shown to be superior compared with pelvic bone matching. With a required PTV margin of 7.17mm in the AP direction, the use of hydrogel tissue marker can significantly improve treatment set up accuracy even in patients with optimal bowel and bladder preparations who undergo image guidance with pelvic bone matching. This will provide the best CTV coverage whilst minimising the current PTV margin and mitigating bladder and rectal toxicities.

Learning Objectives: 1 To illustrate the spectrum of breast lesions on CT 2 To describe CT features predictive of malignancy 3 To discuss further management of CT detected breast lesions Background: Incidental lesions in the breast are commonly detected, in the range of 0.05% to 1.3% of chest CT’s. It is important for general radiologists to be aware of the spectrum of CT appearances to be able to detect these lesions and effect appropriate management. Most breast incidentalomas are reportedly benign and therefore knowledge of benign and malignant features on CT is valuable for stratification of high risk cases. Features predictive of malignancy described in literature include irregular shape, rim enhancement, irregular margins,and higher density. Imaging Findings OR Procedure Details: Benign breast lesions most commonly encountered are fibroadenomata. They have been described as circumscribed, round or oval masses that may demonstrate coarse pop-corn like calcifications. Other benign lesions include post-operative scarring, haematoma/seroma and abscess, for which a past medical history would be valuable. Fibrocystic change in the breast can present as asymmetric soft tissue attenuation on CT. The most common malignant breast lesion is invasive ductal carcinoma (IDC), which on CT is a dense, speculated mass with marked early or peripheral enhancement. 4 There may be adjacent pleomorphic calcifications. Invasive lobular carcinoma is less common, accounting for 10 to 15% of invasive breast cancers. It does not commonly present as a mass due to the infiltrating nature of its growth, causing little disruption of architecture and may therefore present as asymmetric soft tissue density with or without a mass on CT. Conclusion: CT is a common investigation and therefore incidental findings in the breast are potentially frequently encountered by all general radiologists. Although some CT features may be helpful in predicting malignant from benign breast lesions, CT is not the best modality for assessment of breast lesions. Further management generally involves clinical breast examination and ultrasonography. For women above the age of 35, mammography is also indicated and MRI and biopsies may be required. Any suspicion should result in a low threshold for referral for further investigation, preferably to a dedicated breast centre. References 1. Bach AG, Abbas J, Jasaabuu C, Schramm D, Wienke A, Surov A. Comparison between incidental malignant and benign breast lesions detected by computed tomography: A systematic review. JMIRO 57 (2013) 529–533 2. Wen-Chiung Lin, Hsian-He Hsu, Chao-Shiang Li et al. Incidentally detected enhancing breast lesions on chest computed tomography. Korean J Radiol 2011; 12(1):44–51 3. Surov A, Fiedler E, Wienke A, Holzhausen H, Spielman R, Behrmann C. Intramammary incidental findings on staging computer tomography. European J Radiol 81(2012) 2174–2178 4. Harish M, Konda S, MacMahon H, Newstead G. Breast Lesions Incidentally Detected with CT: What the General Radiologst Needs to Know. Radiographics. 2007 October; Vol 27 Issue: suppl 1