Scientific Exhibits

2014 Journal of Medical Radiation Sciences  
Aim: To assess whether intensity modulated radiotherapy (IMRT) offers any advantages compared to three-dimensional conformal radiotherapy (3DCRT) when treating the ilio-inguinal lymph-node basin after therapeutic lymphadenectomy for melanoma. Method: 15 consecutive patients receiving adjuvant radiotherapy (48 Gy in 20 fractions) were selected for the study. Simulation, volume generation and goals for target volume coverage and organ at risk (OAR) avoidance followed departmental protocols. For
more » ... ch patient optimised 3DCRT and IMRT plans were generated with prescriptions in accordance with International Commission on Radiation Unit 50 and 62 (3DCRT) and 83 (IMRT) guidelines. Dose volume histograms were produced for each plan in order to allow direct comparisons of 3DCRT and IMRT plans for each patient. The Wilcoxon signed-rank test was used to compare dose received to both target and OARs from each plan for individual patients. Results: Conformality index was improved by the use of IMRT; median 0.649 (range 0.476-0.808) vs 0.442 (0.288-0.605); W = 2, p ≤ 0.05 for IMRT and 3DCRT respectively. No difference was seen in the homogeneity index; median 10.92 (7.65-28.67) vs 11.17 (8.96-26.69); W = 31, p > 0.05. Median dose to the bowel closest to the target volume was significantly less for IMRT. D1 cc, 10 cc and 40 cc were 48.5 Gy vs 49.7 Gy; 47.8 Gy vs 49.0 Gy and 45.8 Gy vs 48.2 Gy for IMRT and 3DCRT respectively. W values 14, 2 and 10; p ≤ 0.05 for all. Also reduced with IMRT was dose to the ipsilateral femoral neck; median V43.2 Gy, 3.9% (0.1-22.0%) vs 43.2% (12.4-68.5%), W = 0, p ≤ 0.05; and median V36 Gy, 29.5% (14.8-42.3%) vs 61.1% (40.4-100%), W = 0, p ≤ 0.05 for IMRT and 3DCRT respectively. Conclusion: A homogenous coverage of the target volume can be achieved with both IMRT and 3DCRT (homogeneity index <15). However, the use of IMRT appears to allow superior conformality of dose to the target volume while relatively sparing (and potentially reducing the risk of toxicity to) adjacent OARs such as the bowel and femoral neck. Aim: To evaluate the Volumetric Modulated Arc Therapy (VMAT) technique for Malignant Pleural Mesothelioma (MPM) compared with the current fixed-field Intensity Modulated Radiation Therapy (IMRT) technique, evaluating target conformity, target coverage, integral dose and normal tissue sparing. Method: Six patients, three left-sided and three right-sided, treated with a 9 static field IMRT approach to a prescribed dose of 54 Gy in 30 fractions were selected for this study. All patients were replanned using Varian's Eclipse RapidArc® treatment planning software using two full arc rotations. A comparison of the Conformity Index (CI), dose homogeneity and organ at risk (OAR) mean and maximum doses including contralateral lung, heart, liver, kidney, oesophagus and spinal cord were derived and evaluated for IMRT and VMAT plans. Beam on times will also be evaluated and compared between the two techniques. Results: Preliminary findings from the dosimetric evaluation indicate that VMAT generated plans result in superior dose coverage and homogeneity of PTV. The OARs were acceptable according to dose constraints, with reduced mean and max doses for VMAT plans compared with IMRT. The final results of the study will be presented at the Combined Scientific Meeting 2014. All plans were quality assurance checked and are able to be delivered. Conclusion: VMAT demonstrated that it was comparable to IMRT for the treatment of MPM. The outcome of this study will lead to VMAT playing a vital role in the management of MPM, by reducing dose toxicity to OARs, increasing dose conformity to the PTV and reducing overall treatment times. Aim: To examine the significance of eliminating oral contrast from the Emergency Department protocol for abdominopelvic CT examinations. Since the introduction of the National Emergency Access Target (NEAT) in Australia, the efficiency of patient flow through the Emergency Department (ED) has become of greater importance [1] with initial American studies into protocol change showing promising results [2]. Methods: A retrospective analysis was performed on 500 patients before and 500 patients after protocol change at a tertiary care academic adult ED between December 2012 and March 2013. Excluded studies included those for trauma, renal calculi and angiography. Patients continued to have oral contrast at the discretion of the radiologist for subjectively low body mass index. Results: Following protocol change there was a significant reduction in the use of oral contrast: 59% pre and 22% post (p < 0.001). The mean times from request to scanning and request to transcription were both significantly reduced: 10.5 minutes (95% CI 52.6-62.0 versus 43.0-50.6; p = 0.001) and 21.4 minutes respectively (95% CI 169-190 versus 149-167; p = 0.003). Taking into account time of day, the biggest reduction occurred during night shifts. The commonest diagnoses were: diverticulitis 7%, colitis/enteritis 7% and small bowel obstruction 6%. No cause could be found for patient's complaint in 31% cases. Oral contrast was not tolerated in only 4 patients. In only a single study post protocol change was it felt that oral contrast may have been helpful. Cases of equivocal appendicitis were not increased and were in fact less following protocol change (4 case pre and 1 case post; p = 0.04). Conclusion: Eliminating oral contrast from the ED protocol significantly reduces the time to reporting which has the biggest impact overnight. Preliminary results suggest no compromise in diagnosis but further work is required looking into clinico-pathological accuracy. References 1. Khanna S, Boyle J, Good N, Lind J. New emergency department quality measure: from access block to National Emergency Access Target compliance. Emerg Med Australas 2013 Dec; 25(6): 565-72. 2. Levenson RB, Camacho MA, Horn E, Saghir A, McGillicuddy D, Sanchez LD. Eliminating routine oral contrast use for CT in the emergency department: impact on patient throughput and diagnosis. Emerg Radiol 2012 Dec; 19(6): 513-7. Conclusion: To date three patients have been treated on this protocol. After analysis of the PTV and CTV dose coverage additional planning constraints have been generated to indicate minimum dose coverage of OAR/PTV and OAR/CTV overlap regions. Aim: To investigate the feasibility and dosimetric benefit of a temporary spacer between the rectum and the prostate for prostate IMRT. Methods and Materials: After informed consent, 30 patients were enrolled on a prospective ethics approved Phase I/II study. All patients were simulated with CT and MRI before and after injection of 10 cc of Hydrogel. The first 10 patients had an additional MRI at completion of radiation. Hydrogel was injected under general anaesthetic using a transperineal approach. Primary endpoints were perioperative toxicity and rectal dosimetry (V80, V75, V70, V65, V40 and V30). All patients were planned on both the pre and post Hydrogel scans to a D95 of 80 Gy in 40 fractions. Results: 29 of the 30 patients had the procedure performed successfully. No patients reported bleeding or infection following the procedure. In 1 patient gel was injected into the rectal lumen, with no dosimetric benefit and he has been included in this analysis. The gel could only be clearly visualised on MRI. At 12 months follow-up this patient has complained of no rectal side effects. Rectal doses were lower for the Hydrogel patients for all dose endpoints (V80 = 5.3% vs. 0.8%; V75 = 9.5% vs. 2.2%; V70 = 12.3% vs. 3.7%; V65 = 14.7% vs. 5.4%; V40 = 32% vs. 22.9% and V30 = 49.4% vs.42.7%). Early absorption of the gel was seen in 3 patients on the post treatment MRI (n = 10), although separation of the prostate and rectum was still >1 cm. Conclusion: SpaceOAR Hydrogel was successfully injected in 29/30 patients with minimal side effects. Dosimetric benefits were greater at the higher rectal doses (V65 to V80), although lower range rectal doses (V30-V40) were also improved but to a lesser extent. MRI should be used for planning purposes as the gel is not well visualised on CT. Aim: We aim to audit the findings of unenhanced multi-detector CT (CT KUB) for the assessment of acute presentations of renal colic for obstructive urinary calculi versus other findings or no findings in a regional Australian centre and compare this to published primary literature values. Methods: Data were collected retrospectively of 100 consecutive patients who underwent CT KUB for the investigation of obstructive urinary calculi and renal colic. The findings were audited and classified as (1) obstructive urinary calculus found, (2) alternative explanation of pain found in the absence of (1), (3) no cause found. Clinically significant and insignificant incidental findings were also noted separately. Patients with known urinary calculi including progression studies and stent follow-up or placement were excluded. Results: Of the CT KUB scans audited, 58% demonstrated obstructive urinary calculi (a positive scan). Gender analysis found an equal rate of positive scans; however, there were differences in the aetiologies of explained pain in negative scans that are gender specific such as ruptured penile implant in a male and uterine/ovarian pathology in a female. An alternative possible cause of the pain was found in 38% of negative scans. In positive scans, clinically significant incidental findings were discovered in 7% while clinically insignificant findings were discovered in 28% of cases. Negative scans meanwhile found only 1% of clinically significant, and 21% clinically insignificant findings. Conclusion: CT KUB is the mainstay technique in the assessment of obstructive urinary calculi as it is able to detect calculi not visible plain film x-ray 1 . X-ray has a high specificity but low sensitivity (45-58%) for detection of urinary calculi, while CT KUB also demonstrates a high specificity but with a high sensitivity of 96% 2 . The published literature values for positive scan rates are between 44% and 67%, and this audit is consistent with these findings 3,4 . References 1. Patatas K, Panditaratne N, Wah TM, Weston MJ, Irving HC. Emergency department imaging protocol for suspected acute renal colic: re-evaluating our service. The British Journal of Radiology 2012; 85: 1118-22. 2. Chen MY, Zagoria RJ, Saunders HS et al. Trends in the use of unenhanced helical CT for acute urinary colid. AJR Am. J. Roentgenol. 1999; 173: 1447-50. 3. Chowdhury FU, Kotwal S, Raghunathan G et al. Unenhanced multidetector CT (CT KUB) in the initial imaging of suspected acute renal colic: evaluating a new service. Clinical Radiology 2007; 62: 970-77. 4. Jo H and Buckley BT. Assessment of referral patterns for CT KUB in a tertiary setting. Aim: To evaluate the utility of abdominal CT scans requested from the Nambour General Hospital emergency department (Nambour ED) in the diagnosis of non-traumatic acute presentations of abdominal pain. Method: A retrospective analysis of 100 consecutive abdominal CT scans requested from the Nambour ED was conducted. Request forms were audited against the findings of the corresponding radiology reports. The findings of these were categorised as (1) possible cause confirmed, (2) alternative possible cause of symptoms identified in the absence of (1), and (3) no cause found. CT reports that noted poor quality of scans were excluded. Results: From 100 patients, 67 were found to have a possible cause of symptoms. 43 of these 67 positive findings (64%) were the queried cause found as per the request form. 24 of the 67 positive results (36%) found a cause other than that requested. Gender analysis found that females were more likely not only to have a cause found (46% vs. males 37%), but also more likely to have the queried cause found (25% vs. males 21%). The most common single pathological diagnosis was diverticulitis (18%). Further chart review demonstrated a close relationship between the diagnosis at discharge to the diagnosis from the CT scan. Conclusion: Abdominal CT is one of the most useful tools in the assessment of non-traumatic acute abdominal pain in emergency departments and is being utilised at increasing rates 1,2 . There is a strong correlation between the CT diagnosis and the final discharge diagnosis of a patient while a normal scan resulted in a low likelihood for ward admission 3,4 . Furthermore, a normal scan facilitated discharge from the emergency department. Whether a CT scan was required or whether the cause of abdominal pain could be assessed clinically without the need for CT scanning is difficult to ascertain retrospectively. References 1. Nagurney JT, Brown DFM, Chang Y et al. Use of diagnostic testing in the emergency department for patients presenting with nontraumatic abdominal pain.
doi:10.1002/jmrs.74 pmid:27759942 pmcid:PMC4263487 fatcat:ccsk62gef5g47bfugrvtwqapj4