Optimal 99mTc activity ratio in the single-day stress-rest myocardial perfusion imaging protocol: A multi-SPECT phantom study.

BACKGROUND: This investigation used image data generated by an anthropomorphic phantom to determine the minimal 99mTc rest-stress activity concentration ratio (R) able to minimize the ghosting effect in the single-day stress-first myocardial perfusion imaging, using different positions of the perfusion defect (PD), scanners and reconstruction protocols. METHODS: A cardiac phantom with a simulated PD was imaged under different R using different gamma cameras and reconstruction algorithms. The residual activity from precedent stress administration was simulated by modeling effective half-times in each compartment of the phantom and assuming a delay of 3 hours between the stress and rest studies. The net contrast (NC) of the PD in the rest study was assessed for different R, PD positions and scanner/software combinations. The optimal R will be the one that minimize the NC in the rest images RESULTS: The activity concentration ratio R, the position of the PD and the scanner/software combinations were all main effects with a statistically significant impact on the NC, in decreasing order of relevance. The NC diminished significantly only for R values up to 2. No further improvement was observed for NC for R values above 2 and up to 3. NC was significantly higher in anteroseptal than in posterolateral positions of the PD and higher for solid-state cameras. CONCLUSIONS: A rest-stress activity concentration ratio R of 2 in single-day stress-first myocardial perfusion imaging is enough to achieve the maximum net contrast in the PD. This ratio should be used to optimize patient's radiation exposure.

Impact of non-specific normal databases on perfusion quantification of low-dose myocardial SPECT studies.

AIM: To evaluate the impact of non-specific normal databases on the percent summed rest score (SR%) and stress score (SS%) from simulated low-dose SPECT studies by shortening the acquisition time/projection. METHODS: Forty normal-weight and 40 overweight/obese patients underwent myocardial studies with a conventional gamma-camera (BrightView, Philips) using three different acquisition times/projection: 30, 15, and 8 s (100%-counts, 50%-counts, and 25%-counts scan, respectively) and reconstructed using the iterative algorithm with resolution recovery (IRR) AstonishTM (Philips). Three sets of normal databases were used: (1) full-counts IRR; (2) half-counts IRR; and (3) full-counts traditional reconstruction algorithm database (TRAD). The impact of these databases and the acquired count statistics on the SR% and SS% was assessed by ANOVA analysis and Tukey test (P < 0.05). RESULTS: Significantly higher SR% and SS% values (> 40%) were found for the full-counts TRAD databases respect to the IRR databases. For overweight/obese patients, significantly higher SS% values for 25%-counts scans (+19%) are confirmed compared to those of 50%-counts scan, independently of using the half-counts or the full-counts IRR databases. CONCLUSIONS: AstonishTM requires the adoption of the own specific normal databases in order to prevent very high overestimation of both stress and rest perfusion scores. Conversely, the count statistics of the normal databases seems not to influence the quantification scores.

Comparative analysis of iterative reconstruction algorithms with resolution recovery and time of flight modeling for 18F-FDG cardiac PET: A multi-center phantom study.

BACKGROUND: The purpose of this study was to evaluate the image quality in cardiac 18F-FDG PET using the time of flight (TOF) and/or point spread function (PSF) modeling in the iterative reconstruction (IR). METHODS: Three scanners and an anthropomorphic cardiac phantom with an insert simulating a transmural defect (TD) were used. Two sets of scans (with/without TD) were acquired, and four reconstruction schemes were considered: (1) IR; (2) IR + PSF, (3) IR + TOF, and (4) IR + TOF + PSF. LV wall thickness (FWHM), contrast between LV wall and inner chamber (C IC), and TD contrast in LV wall (C TD) were evaluated. RESULTS: Tests of the reconstruction protocols showed a decrease in FWHM from IR (13 mm) to IR + PSF (11 mm); an increase in the C IC from IR (65%) to IR + PSF (71%) and from IR + TOF (72%) to IR + TOF + PSF (77%); and an increase in the C TD from IR + PSF (72%) to IR + TOF (75%) and to IR + TOF + PSF (77%). Tests of the scanner/software combinations showed a decrease in FWHM from Gemini_TF (13 mm) to Biograph_mCT (12 mm) and to Discovery_690 (11 mm); an increase in the C IC from Gemini_TF (65%) to Biograph_mCT (73%) and to Discovery_690 (75%); and an increase in the C TD from Gemini_TF/Biograph_mCT (72%) to Discovery_690 (77%). CONCLUSION: The introduction of TOF and PSF increases image quality in cardiac 18F-FDG PET. The scanner/software combinations exhibit different performances, which should be taken into consideration when making cross comparisons.

Differences in polar-map patterns using the novel technologies for myocardial perfusion imaging.

BACKGROUND: New technologies are available in MPI. Our aim was to evaluate their impact on the uniformity of normal myocardial uptake in the polar-map representation, over different count statistics, with and without the attenuation (AC) and scatter corrections (SC). METHODS: A phantom study was performed using 5 Anger gamma cameras with filtered back projection or iterative reconstruction with resolution recovery (IRR), with or without SCAC; a D530c, with or without AC; and a D-SPECT. Count statistics ranged up to a quarter of the reference for the conventional gamma cameras and up to one half for the advanced scanners. Using polar maps, the segmental uptakes and their uncertainties, the 'global uniformity' of polar maps expressed as the coefficient of variation (COV) among the segmental uptakes and the anterior/inferior (ANT/INF) ratio were calculated. RESULTS: Both segmental uptakes and their uncertainties did not depend on the count statistics in the range studied. An increase in the segmental uptakes was found from IRR to IRR + SCAC (78.0% ± 13.5% vs 86.1% ± 9.4%; P < .0001). COV was lower for D-SPECT (10.1% ± 0.5%) and after SCAC for both conventional (9.9% ± 3.0%) and advanced systems (8.9% ± 1.7%). The ANT/INF ratio was above 1 for IRR (1.12 ± 0.07) and fell slightly below 1 for IRR + SCAC (0.97 ± 0.05). CONCLUSIONS: To compare data from the analysis of polar maps across different systems will require the adoption of specific normality databases, developed for each system and reconstruction method employed.

Comparative analysis of cadmium-zincum-telluride cameras dedicated to myocardial perfusion SPECT: A phantom study.

BACKGROUND: This investigation used image data generated by an anthropomorphic phantom with a cardiac insert for a comparison between two solid state cameras: D-SPECT and D530c. METHODS: For each camera, two sets (with and without a simulated transmural defect (TD)) of scans were acquired starting from the in vivo standard count statistics in the left ventricle (LV). Other two acquisitions corresponding to 150% and 50% of the reference count statistics were acquired. Five performance indices related to spatial resolution, contrast, and contrast-to-noise ratio (CNR) were analyzed. RESULTS: D-SPECT showed a lower LV wall thickness and an inferior sharpness than D530c. No significant differences were found in terms of contrast between LV wall and the inner cavity, TD contrast or CNR. No significant differences were observed in CNR when moving from the reference level of count statistics down to 50% or up to 150% of the counts acquired on the LV. CONCLUSIONS: Our results show that D-SPECT and D530c have different performances. The lack of differences in the image performance indices along the range of count statistics explored, indicates that there is the possibility for a further reduction in the injected activity and/or the acquisition time, for both systems.

Comparative analysis of iterative reconstruction algorithms with resolution recovery for cardiac SPECT studies. A multi-center phantom study.

BACKGROUND: This investigation used image data generated by a physical phantom over a wide range of count statistics to evaluate the effectiveness of several of the newer commercially available SPECT reconstruction iterative algorithms (IRR) in improving perfusion defect contrast and spatial resolution, while controlling image noise. METHODS: A cardiac phantom was imaged using four different gamma cameras over a wide range of counts statistics (from 6 to 0.8 Mcounts). Images were reconstructed with FBP, OSEM, and the IRR available on site. IRR were applied without corrections (IRR NC), with attenuation correction (IRR AC), scatter correction (IRR SC), and attenuation + scatter corrections (IRR SCAC). Four image performance indices related to spatial resolution, contrast, and image noise were analyzed. RESULTS: IRR NC always determined significant improvements in all indices in comparison to FBP or OSEM. Improvements were emphasized with IRR SC and IRR SCAC. Count reduction from 6 to 1.5 Mcounts did not impair the performances of any of the considered indices. CONCLUSIONS: This is the first study comparing the relative performance of different, commercially available, IRR software, over a wide range of count statistics; the additional effect of scatter and attenuation corrections, alone or in combination, was also evaluated. Our results confirm that IRR algorithms produce substantial benefits with respect to conventional FBP or OSEM reconstruction methods, as assessed through different figures of merit, in particular when SC and/or SCAC are also included.

Validation of a new protocol for ¹8F-FDG infusion using an automatic combined dispenser and injector system.

PURPOSE: In nuclear medicine, radiopharmaceuticals are usually administered in unit doses partitioned from multi-dose vials. The partitioning typically takes place in a radiopharmacy, depending on local practice. Automatic, as opposed to manual, partitioning and administration should reduce radiation exposure of the personnel involved, improve the accuracy of the administration and mitigate contamination. This study set out to verify and validate the (18)F-fluorodeoxyglucose (FDG) administration procedure performed using Intego (MEDRAD, Inc., Warrendale, PA, USA), a combined dispenser and injector system. We considered maintenance of sterility and the system's potential to improve, with respect to the manual procedure, the accuracy of net administered (18)F-FDG radioactivity in patients and the radiation protection of operators. METHODS: A media-fill procedure was used to assess whether sterility is maintained during use of the Intego system. Simulating a typical working day's setup and use of the system, we investigated the accuracy of the net administered (18)F-FDG activity obtained with Intego versus the manual dose delivery system. We also measured personnel radiation exposure during use of Intego and during manual administration and recorded and compared environmental doses in the two conditions. RESULTS: The radiopharmaceutical remained sterile in all the tests performed. The accuracy of the net (18)F-FDG activity delivered to the patients was found to be within 3 % points, as required by European Association of Nuclear Medicine (EANM) guidelines on (18)F-FDG imaging procedures. With Intego, the residual radioactivity in the tubing was 0.20 MBq, corresponding to approximately 0.07 % of the mean activity delivered. With manual injection, the residual radioactivity in the syringe averaged 7.37 MBq, corresponding to a mean error of 2.9 % in the delivered dose. During the injection step of the positron emission tomography (PET) procedure, whole-body and extremity radiation exposures were significantly reduced with Intego by 38 and by 94 %, respectively, compared to the levels associated with manual administration (p < 0.05). CONCLUSION: Integoaccurately partitions and administers sterile doses of (18)F-FDG from multi-dose vials. Compared with standard manual (18)F-FDG administration, the new procedure with an automatic dispensing and injection system greatly reduces the extremity dose to the operator involved in the administration of the radiopharmaceutical.

The scientific publications of AIFM members in 2015-2019: A survey of the FutuRuS working group.

PURPOSE: Within the Italian Association of Medical Physics and Health Physics (AIFM) working group "FutuRuS" we carried out a survey regarding the number of the peer-reviewed articles by AIFM members. METHODS: We surveyed papers published in the years 2015-2019. Data extracted from Scopus included information regarding authors, title, journal, impact factor (IF), leading or standard authorship by AIFM members, keywords, type of collaboration (monocentric/multicentric/international), area of interest [radiation oncology (RO), radiology (RAD), nuclear medicine (NM), radioprotection (RP) and professional issue (PI)] and topics. RESULTS: We found 1210 papers published in peer-reviewed journals: 48%, 22%, 16%, 6%, 2 and 6% in RO, RAD, NM, RP, PI and other topics, respectively. Forty-seven percent of the papers involved monocentric teams, 31% multicentric and 22% international collaborations. Leading authorship of AIFM members was in 56% of papers, with a corresponding IF equal to 52% of the total IF (3342, IFmean = 2.8, IFmax = 35.4). The most represented journal was Physica Medica, with 15% of papers, while a relevant fraction of IF (54%) appeared in clinically oriented journals. The number of papers increased significantly between 2015 and 2016 and remained almost constant in 2017-2019. CONCLUSIONS: This survey led to the first quantitative assessment of the number and theme distribution of peer-reviewed scientific articles contributed by AIFM members. It constitutes a ground basis to support future AIFM strategies and promote working groups on scientific activity of medical physicists, and to build the basis for rational comparison with other countries, first of all within Europe.

Characterization of preclinical models of prostate cancer using PET-based molecular imaging.

PURPOSE: Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice spontaneously develop hormone-dependent and hormone-independent prostate cancer (PC) that potentially resembles the human pathological condition. The aim of the study was to validate PET imaging as a reliable tool for in vivo assessment of disease biology and progression in TRAMP mice using radioligands routinely applied in clinical practice: [(18)F]FDG and [(11)C]choline. METHODS: Six TRAMP mice were longitudinally evaluated starting at week 11 of age to visualize PC development and progression. The time frame and imaging pattern of PC lesions were subsequently confirmed on an additional group of five mice. RESULTS: PET and [(18)F]FDG allowed detection of PC lesions starting from 23 weeks of age. [(11)C]Choline was clearly taken up only by TRAMP mice carrying neuroendocrine lesions, as revealed by post-mortem histological evaluation. CONCLUSION: PET-based molecular imaging represents a state-of-the-art tool for the in vivo monitoring and metabolic characterization of PC development, progression and differentiation in the TRAMP model.

Impact of low-dose SPECT imaging on normal databases and myocardial perfusion scores.

PURPOSE: We have recently demonstrated that iterative reconstruction algorithms with resolution recovery require the adoption of specific normal databases (NDBs) for perfusion SPECT quantification. This work was aimed at investigating the impact of patient low-dose imaging on NDBs and percent summed rest (SR%) and stress (SS%) scores. METHODS: Assuming that count statistics of shorter acquisition time may simulate that of lower patient dose, three simultaneous scans were acquired (BrightView, Philips) with different acquisition-time/projection: 30, 15 and 8 s (from 100% to 25% of the reference). Fifty-two normal patients with low likelihood of coronary artery disease were enrolled and three homemade NDBs were then generated and compared (Astonish™ algorithm with default parameters): 100%-HM-NDBs, 50%-HM-NDBs and 25%-HM-NDBs. SR% and SS% were subsequently calculated for another group of 38 patients (normal/abnormal = 5/33). SR% and SS% values of 100%-HM-NDBs were compared with those obtained with the NDBs available on the workstation. Moreover, the impact of the study count statistics on perfusion scores was evaluated using the count-specific NDBs. RESULTS: Significantly higher standard-deviation values were found for 25%-HM-NDBs compared to the other HM-NDBs (p < 0.02). Significantly higher SS% were also found for the 100%-HM-NDBs compared to the workstation NDBs (95%CI: 0.15-2.11%). Moreover, a post-hoc test showed significantly lower SR% and SS% for 25%-count statistics compared to 100%-HM-NDBs (p < 0.03). CONCLUSIONS: NDBs and perfusion scores depend significantly on study count-statistics. A 50% reduction in patient dose is ultimately the limit for Astonish™ (with the default parameters) in order to prevent a significant variation in myocardial perfusion quantification.

Microwave ablation of malignant renal tumours: intermediate-term results and usefulness of RENAL and mRENAL scores for predicting outcomes and complications.

The aim of this study was to evaluate intermediate-term results after microwave ablation (MWA) of renal tumours and determine the association of RENAL and modified RENAL (mRENAL) scores with oncological outcomes and complications. In May 2008-September 2014, 58 patients affected by early-stage RCC (renal cell carcinoma; T1a or T1b) were judged unsuitable for surgery and treated with percutaneous MWA. Follow-up was performed with contrast-enhanced computed tomography at 1, 3, 6, 12 and 24 months after the procedure. Technical success (TS), primary technical effectiveness (PTE), secondary technical effectiveness (STE), the local tumour progression rate (LTPR), the cancer-specific survival rate (CSSR), disease-free survival (DFS), overall survival (OS) and safety were recorded. All lesions were evaluated using RENAL and mRENAL scores, and complications were assessed with RENAL scores. The TS rate was 100%, PTE was 93%, STE was 100%, LTPR was 15.7% at 1 year, CSSR was 96.5%, DFS was 87.9% at 5 years, and OS was 80.6%. Mean follow-up was 25.7 months (range 3-72). The mean ± standard deviation (SD) RENAL and mRENAL scores of all treated tumours were 6.7 ± 2.05 (range 4-11) and 7 ± 2.3 (range 4-12), respectively. Major complications occurred in two (2/58) and minor complications in three patients (3/58). Overall complications correlated significantly with RENAL scores; in particular, E and L represent negative predictors for safety and effectiveness. MWA is a valuable alternative for treating RCCs. The correlation with outcomes and complications of RENAL and mRENAL scores could help to customise MWA indications in RCC patients.

Comparative analysis of iterative reconstruction algorithms with resolution recovery and new solid state cameras dedicated to myocardial perfusion imaging.

New technologies are available in myocardial perfusion imaging. They include new software that recovers image resolution and limits image noise, multifocal collimators and dedicated cardiac cameras in which solid-state detectors are used and all available detectors are constrained to imaging just the cardiac field of view. These innovations resulted in shortened study times or reduced administered activity to patients, while preserving image quality. Many single center and some multicenter studies have been published during the introduction of these innovations in the clinical practice. Most of these studies were lead in the framework of "agreement studies" between different methods of clinical measurement. They aimed to demonstrate that these new software/hardware solutions allow the acquisition of images with reduced acquisition time or administered activity with comparable results (as for image quality, image interpretation, perfusion defect quantification, left ventricular volumes and ejection fraction) to the standard-time or standard-dose SPECT acquired with a conventional gamma camera and reconstructed with the traditional FBP method, considered as the gold standard. The purpose of this review is to provide the reader with a comprehensive understanding of the pro and cons of the different approaches summarizing the achievements reached so far and the issues that need further investigations.

Clinical impact of cone beam computed tomography on iterative treatment planning during ultrasound-guided percutaneous ablation of liver malignancies.

A standardized cone beam computed tomography (CBCT) protocol may impact optimal ablation probe(s) positioning during ultrasound-guided microwave ablation (MWA). To evaluate this hypothesis, 15 patients underwent ultrasound-guided percutaneous MWA of 15 liver lesions (10 hepatocellular carcinomas, 5 metastasis ranging 11-41 mm) with the ultrasound guidance assisted by a dedicated CBCT protocol. Pre-procedural enhanced CBCT (ceCBCT) was performed after intravenous contrast administration to visualize the lesion and determine the optimal approach using CBCT-based ablation planning software. MW antennas were positioned under ultrasound guidance, and non-enhanced CBCT was performed after deployment and fused with pre-procedural ceCBCT to assess tumor targeting and modify subsequent steps of the procedure. CBCT lesion detection accuracy and number of needle repositioning on the basis of CBCT information were recorded. Clinical success was measured on 1-month follow-up contrast-enhanced CT. The target lesion was detected on ceCBCT in 13 out of 15 patients (87%). The undetected lesions were only visible on diagnostic contrast-enhanced magnetic resonance imaging, which was then fused to the CBCT and fluoroscopy to facilitate targeting. MW antennas were repositioned on the basis of CBCT in 11 lesions (73%). Clinical success was achieved in 14/15 ablations (93%) with a mean follow-up of X months. The only case of local recurrence was expected, as the intent was tumor debulking. CBCT imaging during ultrasound-guided liver ablation is feasible and leads to ablation device repositioning in the majority of cases.

Variability of [18F]FDG administered activities among patients undergoing PET examinations: an international multicenter survey.

Given the large number of [(18)F]fluorodeoxyglucose (FDG) PET examinations performed annually throughout the world, reduction of the administered activity without compromise of the clinical information being sought is encouraged. Guidelines issued by the SNMMI and European Association of Nuclear Medicine (EANM) differ greatly on the choice of the activity that should be administered to patients: the EANM suggests a personalised activity based on the patient's body weight, whereas the SNMMI recommends the administration of fixed activities. The authors analysed a database of 24 716 [(18)F]FDG administrations performed worldwide in 15 PET centres to assess the degree of heterogeneity, in relation to available technology, operational protocols and reference guidelines. Median activities based on the patients' body weight were 43 % lower than fixed-activity administrations (p < 0.001). When TOF scanners are available, the median activity is lowered, but when comparing centres with the same technology or those that use the same operational protocols, weight-based activities are still significantly lower than fixed activities.

Correlation between 123I-FP-CIT brain SPECT and parkinsonism in dementia with Lewy bodies: caveat for clinical use.

INTRODUCTION: Although parkinsonism is considered a core feature of dementia with Lewy bodies (DLB), it is occasionally mild or even absent. I-FP-CIT SPECT has been accepted as a diagnostic support tool in this context, given that low striatal uptake is associated with neuronal loss. The aim of this retrospective study was to look for correlations between I-FP-CIT uptake in the striatum and clinical extrapyramidal signs (EPSs) in patients with a diagnosis of probable DLB to clarify the extent to which the supporting role of I-FP-CIT is related to motor impairment. METHODS: Semiquantitative I-FP-CIT uptake was analyzed and correlated with Unified Parkinson Disease Rating Scale Part III scores in a sample of 22 patients with a diagnosis of probable DLB and a wide range of EPSs. RESULTS: A significant negative linear correlation between I-FP-CIT uptake and Unified Parkinson Disease Rating Scale Part III score was found both in the caudate and the putamen (r = -0.69 and -0.72, respectively, P < 0.001). Striatal uptake in patients with no or questionable EPS was comparable to that recorded in normal age-matched subjects (99% [22%] in the putamen) but significantly reduced in those with mild and severe EPS (43% [35%] and 30% [17%], respectively, P < 0.0001, but P = nonsignificant between mild and severe EPS). CONCLUSIONS: SPECT may be redundant when there are no doubts about the parkinsonism (ie, when it is absent or unequivocally present), but it may be helpful in identifying presynaptic nigrostriatal degeneration in patients with mild EPSs.

Evaluation of renal function in elderly patients: performance of creatinine-based formulae versus the isotopic method using 99mTc-diethylene triamine pentaacetic acid.

INTRODUCTION: Measurement of the glomerular filtration rate (GFR) is recognized worldwide as the most accurate way of assessing kidney function. The prevalence of impaired renal function increases with advancing age. In this study we compared the clinical formulae Cockcroft-Gault (CG), isotope dilution mass spectrometry-modification of diet in renal disease (IMDS-MDRD) and chronic kidney disease epidemiology collaboration (CKD-EPI) with (99m)Tc-diethylene triamine pentaacetic acid ((99m)Tc-DTPA) in elderly patients over and under the age of 70 years in an attempt to establish which formula produces the best measurement of renal function in this population. MATERIALS AND METHODS: Patients were randomly selected from two age groups [<70 years (n = 37) and ≥ 70 years (n = 39)]. Two plasma samples were collected at 60 and 180 min after injection of (99m)Tc-DTPA, and the GFR was calculated applying Charles D. Russell's two-sample method. RESULTS: In patients younger than 70 years, no statistically significant difference was found between GFR evaluated with (99m)Tc-DTPA and GFR obtained using the other methods.In patients aged at least 70 years, no statistically significant difference was found between GFR evaluated with (99m)Tc-DTPA and GFR evaluated using the CG real weight formula. Conversely, statistically significant differences were found between GFR evaluated with (99m)Tc-DTPA and GFR obtained using the CG normalized weight (P = 0.002), IMDS-MDRD (P = 0.024) and CKD-EPI (P = 0.028) formulae. DISCUSSION AND CONCLUSION: In patients older than 70 years, the use of the two 'classical' formulae (IMDS-MDRD and CKD-EPI) overestimated GFR in stage III CKD (GFR 30-59 ml/min) when compared with the gold standard (99m)Tc-DTPA method. Thus, in patients aged 70 years and above only the CG real weight formula provided unbiased results comparable to (99m)Tc-DTPA. In conclusion, in elderly patients, GFR measured using CKD-EPI and IMDS-MDRD serum creatinine-based formulae may be overestimated compared with that measured using (99m)Tc-DTPA GFR.

Current concepts on imaging in radiotherapy.

New high-precision radiotherapy (RT) techniques, such as intensity-modulated radiation therapy (IMRT) or hadrontherapy, allow better dose distribution within the target and spare a larger portion of normal tissue than conventional RT. These techniques require accurate tumour volume delineation and intrinsic characterization, as well as verification of target localisation and monitoring of organ motion and response assessment during treatment. These tasks are strongly dependent on imaging technologies. Among these, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and positron emission tomography (PET) have been applied in high-precision RT. For tumour volume delineation and characterization, PET has brought an additional dimension to the management of cancer patients by allowing the incorporation of crucial functional and molecular images in RT treatment planning, i.e. direct evaluation of tumour metabolism, cell proliferation, apoptosis, hypoxia and angiogenesis. The combination of PET and CT in a single imaging system (PET/CT) to obtain a fused anatomical and functional dataset is now emerging as a promising tool in radiotherapy departments for delineation of tumour volumes and optimization of treatment plans. Another exciting new area is image-guided radiotherapy (IGRT), which focuses on the potential benefit of advanced imaging and image registration to improve precision, daily target localization and monitoring during treatment, thus reducing morbidity and potentially allowing the safe delivery of higher doses. The variety of IGRT systems is rapidly expanding, including cone beam CT and US. This article examines the increasing role of imaging techniques in the entire process of high-precision radiotherapy.