X-ray services were first established in Singapore in 1898. With the opening of the General Hospital in 1926, there was subsequent increase in workload. However, a radiology department was not formed until the 1950s. Angiography was introduced in the same decade initially for diagnosis. By the 1960s and 1970s, both vascular and non-vascular interventions were performed. Subsequently, interventional radiology experienced exponential growth, with newer technology and better facilities established over the past 3 decades. With more trained interventional radiologists, the service is currently available in all public hospitals and in most private hospitals in Singapore today. It is envisaged that structured training and formal credentialing will be established, eventually leading to recognition of interventional radiology as a specialty in its own right.

Objectives: To determine the clinical, imaging and pathological findings of Paget’s disease of the breast. Materials and methods: Approval by Institutional Review Board was granted and informed consent was waived. Retrospective review of the pathological diagnosis of 2,361 women with breast carcinoma between January 2004 and April 2010 revealed 27 patients with Paget’s disease of the breast. The clinical, mammographic and ultrasonographic images were retrospectively reviewed. Results: The prevalence of Paget’s disease of the breast was 1.14% of all breast carcinoma at this institution. Of the 27 patients with Paget’s disease, only 16 had imaging studies and this group constituted the basis of this study. All 16 patients were women, with ages ranging from 36–68 years (mean age 50.31 years). Eleven patients presented with clinical findings suggestive of Paget’s disease of the breast. Seven of these 11 patients also had associated palpable mass(es). Four patients presented with a palpable mass alone and one presented with bloody nipple discharge alone. Mammography was performed in all 16 patients and ultrasonography (US) in 15 patients. Of the 16 mammographic studies, two were negative. Of the 15 US studies, three were negative. Of these three negative US studies, two also had negative mammography and one had pleomorphic microcalcifications on mammogram. US was helpful in detecting multifocality in two patients. Mammography was 100% positive in patients who presented with palpable breast mass(es) and bloody nipple discharge, but 50% positive in patients who had clinically suggestive Paget’s disease alone. Almost all patients (15/16) had underlying breast malignancies. Seven patients had multifocality or multicentricity. Modified radical mastectomy was performed in 13 patients, simple mastectomy in two, and wide local excision in one patient. Pathological findings were ductal carcinoma in situ (DCIS) (n = 3), invasive ductal carcinoma (IDC) (n = 10), metaplastic carcinoma (n = 1), invasive lobular carcinoma (ILC) (n = 1), and only Paget’s disease of the nipple without underlying breast carcinoma (n = 1). Conclusion: Patients with Paget’s disease of the breast have a high incidence of an underlying breast carcinoma. Most of the patients in this study presented late and were more likely to have positive mammograms. Mammography should be performed to identify the underlying breast carcinoma. Those who have only nipple areolar changes and no palpable mass have less positive mammography and less invasive carcinoma.

Purpose: The purpose of the study was to investigate the diagnostic value of SPECT, PET and PET/CT in the diagnosis of coronary artery disease, based on a systematic review. Material and Methods: A search of PubMed/Medline and Sciencedirect databases in the English-language literature published over the last 24 years was performed. Only studies with at least 10 patients comparing SPECT, PET or combined PET/CT with invasive coronary angiography in the diagnosis of coronary artery disease (50% stenosis) were included for analysis. Sensitivities and specificities estimates pooled across studies were analysed using a Chisquare test. Results: Twenty-five studies met the selection criteria and were included for the analysis. Ten studies were performed with SPECT alone; while another six studies were performed with PET alone. Five studies were carried out with both PET and SPECT modalities, and the remaining four studies were investigated with integrated PET-CT. The mean value of sensitivity, specificity and accuracy of these imaging modalities for the diagnosis of coronary artery disease was 82% (95%CI: 76 to 88), 76% (95%CI: 70 to 82) and 83% (95%CI: 77 to 89) for SPECT; 91% (95%CI: 85 to 97), 89% (95%CI: 83 to 95) and 89% (95%CI: 83 to 95) for PET; and 85% (95%CI: 79 to 90), 83% (95%CI: 77 to 89) and 88% (95%CI: 82 to 94) for PET/CT, respectively. The diagnostic accuracy of these imaging modalities was dependent on the radiotracers used in these studies, with ammonia resulting in the highest diagnostic value. Conclusion: Our review shows that PET has high diagnostic value for diagnosing coronary artery disease, and this indicates that it is a valuable technique for both detection and prediction of coronary artery disease.

Purpose: The imaging characteristics of two popular kV cone-beam CT (CBCT) and two MVCT systems utilised in image-guided radiation therapy (IGRT) were evaluated. Materials and methods: The study was performed on Varian Clinac iX, Elekta Synergy S, Siemens Oncor, and Tomotherapy. A CT phantom (Catphan-504, Phantom Laboratory, Salem, NY) was scanned for measurements of image quality including image noise, uniformity, density accuracy, spatial resolution, contrast linearity, and contrast resolution. The measurement results were analysed using in-house image analysis software. Reproducibility, position correction, and geometric accuracy were also evaluated with markers in a smaller alignment phantom. The performance evaluation compared volumetric image properties from these four systems with those from a conventional diagnostic CT (CCT). Results: It was shown that the linearity of the two kV CBCT was fairly consistent with CCT. The Elekta CBCT with half-circle 27-cm FOV had higher CT numbers than the other three systems. The image noises of the Elekta kV CBCT, Siemens MV CBCT, and Tomotherapy fan-beam CT (FBCT) are about 2-4 times higher than that of the Varian CBCT. The spatial resolutions of two kV CBCTs and two MV CBCTs were 8-11 lp/cm and 3-5 lp/cm, respectively. Conclusion: Elekta CBCT provided a faster image reconstruction and low dose per scan for half-circle scanning. Varian CBCT had relatively lower image noise. Tomotherapy FBCT had the best uniformity.

Objective: To optimize the delay time before the initiation of arterial phase scan in the detection of focal liver lesions in contrast enhanced 5 phase liver CT using the bolus tracking technique. Patients and Methods: Delay - the interval between threshold enhancement of 100 hounsfield unit (HU) in the abdominal aorta and commencement of the first arterial phase scan. Using a 16 slice CT scanner, a plain CT of the liver was done followed by an intravenous bolus of 120 ml nonionic iodinated contrast media (370 mg I/ml) at the rate of 4 mL/s. The second phase scan started immediately after the first phase scan. The portal venous and delay phases were obtained at a fixed delay of 60 s and 90 s from the beginning of contrast injection. Contrast enhancement index (CEI) and subjective visual conspicuity scores for each lesion were compared among the three groups. Results: 84 lesions (11 hepatocellular carcinomas, 17 hemangiomas, 39 other hypervascular lesions and 45 cysts) were evaluated. CEI for hepatocellular carcinomas appears to be higher during the first arterial phase in the 6 seconds delay group. No significant difference in CEI and mean conspicuity scores among the three groups for hemangioma, other hypervascular lesions and cysts. Conclusion: The conspicuity of hepatocellular carcinomas appeared better during the early arterial phase using a bolus tracking technique with a scan delay of 6 seconds from the 100 HU threshold in the abdominal aorta.

Purpose: To determine: (i) the mammographic parenchymal patterns in Malaysian women and whether the breasts are dense on mammogram; (ii) the effect of age on breast density; (iii) the effect of parity on breast density; (iv) the difference in breast parenchymal patterns among the major races of women in Malaysia. Methods: This was a descriptive cross-sectional study of 1,784 patients (981 Malays, 571 Chinese, 214 Indians and 18 others) who had undergone mammography during the 1-year study period. Majority of women (41.7%) were aged between 51 and 60 years and majority (43%) had 3–4 children. The Tabar classification (Pattern I - V) was used to evaluate breast parenchymal patterns on mammogram. Tabar Pattern I was further divided into 3 sub-groups (Pattern IA, IB, and IC). The different patterns were then grouped into dense (IB, IC, IV, V) and not dense (IA, II, III) breasts. The SPSS package was used for statistical analysis. Results: Majority (59%) of Malaysian women had dense breasts (Pattern IB 29%, IC 20%, IV 5%, and V 5%) and 41% did not have dense breasts (Pattern IA 28%, II 6%, and III 7%). Age and parity were inversely related to breast density (p < 0.0001). Chinese women (65.7%) had the highest percentage of dense breasts (p = 0.69, odds ratio = 1.22), followed by the Indians (57.2%) and the Malays (50.5%). Conclusion: Majority of women had dense breasts but Pattern IV, which has been associated with increased risk of breast cancer, was seen in only 5% of the women. The breast density reduced steadily with increasing age and parity. There was no statistically significant difference in breast density in the three main races.

The preceding DIN 6800-2 (1997) protocol has been revised by a German task group and its latest version was published in March 2008 as the national standard dosimetry protocol DIN 6800-2 (2008 March). Since then, in Germany the determination of absorbed dose to water for high-energy photon and electron beams has to be performed according to this new German dosimetry protocol. The IAEA Code of Practice TRS 398 (2000) and the AAPM TG-51 are the two main protocols applied internationally. The new German version has widely adapted the methodology and dosimetric data of TRS-398. This paper investigates systematically the DIN 6800-2 protocol and compares it with the procedures and results obtained by using the international protocols. The investigation was performed with 6 MV and 18 MV photon beams as well as with electron beams from 5 MeV to 21 MeV. While only cylindrical chambers were used for photon beams, the measurements of electron beams were performed by using cylindrical and plane-parallel chambers. It was found that the discrepancies in the determination of absorbed dose to water among the three protocols were 0.23% for photon beams and 1.2% for electron beams. The determination of water absorbed dose was also checked by a national audit procedure using TLDs. The comparison between the measurements following the DIN 6800-2 protocol and the TLD audit-procedure confirmed a difference of less than 2%. The advantage of the new German protocol DIN 6800-2 lies in the renouncement on the cross calibration procedure as well as its clear presentation of formulas and parameters. In the past, the different protocols evoluted differently from time to time. Fortunately today, a good convergence has been obtained in concepts and methods.

Radiofrequency ablation (RFA) therapy is recognised as a safe and effective treatment option for osteoid osteoma. This case report describes a 27-year-old man who underwent computed tomography (CT)-guided percutaneous RFA for a femoral osteoid osteoma, which was diagnosed based on his clinical presentation and CT findings. The patient developed worsening symptoms complicated by osteomyelitis after the procedure. His clinical progression and subsequent MRI findings had led to a revised diagnosis of a Brodie’s abscess, which was further supported by the eventual resolution of his symptoms following a combination of antibiotics treatment and surgical irrigations. This case report illustrates the unusual MRI features of osteomyelitis mimicking soft tissue tumours following RFA of a misdiagnosed Brodie’s abscess and highlights the importance of a confirmatory histopathological diagnosis for an osteoid osteoma prior to treatment.

John Cameron has made significant contributions to the field of Medical Physics. His contributions encompassed research and development, technical developments and education. He had a particular interest in the education of medical physicists in developing countries. Structured clinical training is also an essential component of the professional development of a medical physicist. This paper considers aspects of the clinical training and education of medical physicists in South-East Asia and the challenges facing the profession in the region if it is to keep pace with the rapid increase in the amount and technical complexity of medical physics infrastructure in the region.

Purpose: To ascertain the effectiveness of the clinical, tutorial-based component of teaching and the clinical assessment method in the Bachelor of Medical Imaging Science at Curtin University of Technology (CUT), Perth, Western Australia. Materials and Methods: In mid-2006, second- and third-year students enrolled in CUT’s Medical Imaging Science degree were asked to complete a questionnaire assessing the Objective Structured Clinical Examination (OSCE) evaluation program and clinical teaching. Thirty-three of 57 students answered questions about demographics and their opinions of the laboratory sessions, clinical placements and the OSCEs. Results: Seventy-six per cent of students were satisfied with their laboratory sessions and clinical placements. Sixty-four per cent of respondents indicated that the OSCE was not an objective evaluation, but 82% of students felt the OSCE was an effective test of their radiography skills and knowledge, and believed that they were able to evaluate and care for a patient during the OSCE. Conclusion: Overall, the surveyed students believed that the practical skills explored in laboratory sessions helped improve clinical training outcomes; however, only 33% of the students were satisfied that the OSCE was an appropriate assessment of their clinical training in hospitals.