News | Jul 20, 2020

The first digital PET/CT imaging system in Poland

In the issue 2/2020 of the magazine "Inżynier i Fizyk Medyczny" we recommend an article written by Agata Zakrzewska on the first digital positron tomography system PET-CT in Poland.

Agata Zakrzewska
Product&Application Manager MI CT United Imaging Healthcare Poland

 

The first digital positron tomography system in Poland — a United Imaging Healthcare uMI550 scanner — was installed in Warsaw in December 2019. The first positron emission tomography/computed tomography (PET/CT) scans were performed at the beginning of 2020. The owner of the newly opened laboratory is Krzysztof Toth, MD PhD — the founder of NUKLEOMED — the first private nuclear medicine clinic in Poland.

 

PET/CT laboratory in Nukleomed, Warsaw

 

 

Global position of United Imaging Healthcare

United Imaging Healthcare is an innovative medical company established in 2011 in Shanghai. Its research and development centres are located in China, the USA and other regions of the world. Over a half of the company’s 5,000 employees are scientists working with research sites.
The all-digital portfolio of United Imaging includes the following PET/CT systems: uMI550, uMI780 and the unique worldwide total body PET/CT uExplorer scanner with a 194 cm axial field of view (FOV) that enables the whole body to be scanned in one bed position.

 

 

 

 

Installation of the first PET/CT imaging system in Poland

Why have you decided to expand the scope of diagnostics you offer to include positron computed tomography?
– In Nukleomed we have equipment which enables us to perform full-scope scintigraphy, which is a technique of conventional nuclear medicine.

 

 

 

The clinic boasts a total of four gamma cameras, including three dual-head devices, one of which is a cutting-edge SPECT-CT machine. We “only” needed a PET/CT scanner “for perfect happiness”. The importance of conventional nuclear medicine in imaging techniques cannot be underestimated. Nevertheless, nowadays it is difficult to imagine a complete nuclear medicine facility without a PET/CT scanner. PET/CT is a standard in modern diagnostic imaging, especially at different stages of oncological diagnostics, including in the process of choosing appropriate targeted therapy and treatment effectiveness assessment.

 

Why did you choose a United Imaging system?
– Paradoxically, due to limited financial resources, we cannot afford to make purchases as needed or with a single project or idea in mind. The device needs to be very advanced, support a number of optional enhancements and have high level technical specifications, which will ensure high quality examination in the long-term.
From the very beginning the offer of United Imaging was attractive due to the very good technical parameters of both the PET and the CT scanner, and, most importantly, it came with a very advanced design of the digital PET scanner. The quality to cost estimation for the equipment with optional enhancements, processing stations and service agreement was in favour of the ultimately selected manufacturer.

 

What challenges did you face in the process of installing the PET/CT system in your clinic?
– The assumed time-frame of the PET/CT project necessitated complete reconstruction of the space in which the new laboratory was going to be built. We had to do this relatively quickly — before the installation began. The new unit with a “hot” isotope lab, radiopharmaceuticals injection station, a specially designed patient waiting room area, a scan room and a control room was built where a lecture hall was previously located. The partition walls shield against radiation and the unit is equipped with separate ventilation, lighting and emergency lighting systems. Moreover, there is a separate exit for patients who underwent the exam and the flow of patients is monitored with a video surveillance system which can be used to broadcast information through speakers. Apart from the construction works, another challenge was to obtain the relevant National Atomic Energy Agency (PAA) and Provincial Sanitary and Epidemiological Stations (WSSE) permits in time. We had some concerns associated with the fact that the United Imaging PET/CT scanner installation was the first one in Europe and would be performed by Chinese specialists in cooperation with a local service team. Luckily, the cooperation between the two teams went smoothly. The device was installed, the first test was run, and we are completely satisfied with the acquired images.

 

 

 

Fundamentals of PET/CT imaging

Positron emission tomography is a technique used for imaging of metabolic processes at a cellular level that uses tracers containing positron-emitting isotopes and as such may detect the early onset of pathological changes in the body. The method involves the administration of an isotope tracer to the patient followed by the detection of two gamma photons of 511 keV each, emitted by the radiopharmaceutical, which are released as a result of electron-positron annihilation. The photons are emitted directly from the cells in which the isotope accumulated, then recorded with detectors arranged in a circular array and subsequently transformed into a digital scintigraphic image with the use of a computer system. Due to the fact that the spatial resolution of PET scanners is insufficient for precise localization of areas with specific metabolic activity within the body, fusion imaging involving functional PET and structural CT scans is used. Multimodal PET/CT using fluoro-18 (18F) labelled deoxyglucose [18F]-FDG is a basic diagnostic method used for imaging of neoplastic changes metabolism, staging the disease and evaluation of cancer therapy effectiveness. The 18F-FDG PET/CT procedure is considered extended diagnostics performed in order to determine metabolic activity and stage tumours, including detection of possible metastases and monitoring after the completion of treatment provided under the oncological package of the National Health Fund. Patients eligible for PET/CT examination suffer from neoplastic diseases such as: lung cancer (single lung tumours of > 1 cm in diameter, differential diagnostics of benign and malignant neoplasms, non-small lung cancer), Hodgkin’s lymphoma and non-Hodgkin’s lymphoma, colorectal cancer, oesophageal cancer, pancreatic cancer, liver cancer, breast cancer, melanomas, ovarian cancer, epithelial cancer of head and neck, undifferentiated thyroid cancer, poorly differentiated thyroid cancer, testicular cancer, prostate cancer, renal cancer, sarcomas and gastrointestinal stromal tumours.

 

 

 

Latest technologies in nuclear medicine

The increasing use of PET/CT diagnostics in healthcare promotes the search for novel technologies for construction solutions as well as reconstruction algorithms in order to optimize test procedures. Advancements in the design of gamma-ray detectors with greater sensitivity and detection performance result in a reduction of the examination time and potentially of the dose of radioisotope administered to the patient.

 

 

 

Silicon detectors

Digital PET/CT scanners are the latest technology designed to support specialists in nuclear medicine. Through enhanced precision and performance of coincident gamma quanta, the sensitivity of this method and resolution of the scan is increased.

The innovative design of digital systems is based on the use of silicon photomultipliers (SiPM) instead of the analogue ones. After gamma rays are converted to photons within a lutetium yttrium oxyorthosilicate crystal (LYSO), direct light conversion into an electrical signal takes place in the SiPM. This translates to improvements in light yield and energy resolution, which in turn enhances image quality determining diagnostic capabilities of the system.

 

 

 

Scintillation crystal

Apart from the use of digital SiPM detectors, the type of scintillation crystal is also of crucial importance for the process of diagnostic image generation.
All United Imaging systems use mixed lutetium-based crystals — LYSO ((Lux Y1-x)2SiO5). The crystal has high density of 7.1 g/cm3, which makes it a good energy absorber. Moreover, LYSO is characterized by high light yield of ~ 33,200 photons/MeV, which is 3–4 times better compared to bismuth germanate (BGO) used in analogue systems. The use of LYSO crystals also ensures lower noise than lutetium oxyorthosilicate (LSO), while maintaining satisfactory scintillation properties.
However, spatial resolution is influenced not only by the scintillation crystal’s material properties, but also by its dimensions. All MI United Imaging systems use 2.76 x 2.76 mm crystals, which are the smallest scintillation crystals in PET/CT devices available on the market. Consequently, PET/CT scanners produced by United Imaging have 2.9 mm NEMA (National Electrical Manufacturers Association) spatial resolution.

 

 

 

Axial FOV

Z-axis field of view is the decisive parameter influencing the scanning time. The greater the coverage, the fewer bed positions are needed to acquire data from scanned areas. Shorter scan time allows for an increase in patient throughput, which also directly translates to the activities used.
United Imaging systems currently boast the longest z-axis field of view — from 24 cm in the standard system, up to 194 cm in the total body PET/CT uExplorer.

 

United Imaging Healthcare Poland

“I have always considered trust to be the most important value in business. For this reason, we look for business partners with whom we can establish long-term relations. We try to find people ready to believe in a new organization and its values. We, on our part, will make every effort to be worthy of that trust”, says Łukasz Mizerka, Managing Director for Central and Eastern Europe.

How would you sum up the first, initial period of the company’s operations?
– I was aware that introducing a completely new brand onto the diagnostic imaging market was not going to be an easy task. This makes us even prouder of what we achieved in our first year. We have been noticed. We installed the first devices in Poland, including a PET/CT scanner. Since this is the first digital system of this type set up in Poland, we are particularly proud.
I am immensely thankful to dr Krzysztof Toth for trusting in us and choosing our company to complete the project. Every single agreement we sign is not only an honour and an award for our hard work, but also a challenge we must face in the particularly competitive environment.

 

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