سید ربیع مهدوی

Radiation therapy is one of the most important methods in treatment of cancer. Targeted metal nanoparticles (NPs) play an effective role in reducing ionizing radiation side effects through increasing the effect of ionizing radiation on cancer cells and controlling the harmful effect of radiation on healthy cells. The purpose of this study was to investigate the effect of targeted folic acid gold NPs (GNPs) using linker bovine serum albumin in the absorption and sensitivity of gold NPs in HeLa cervical cancer cells compared to non-targeted gold NPs.

In this study, GNPs were conjugated with folic acid by bovine serum albumin as the linker. The binding of bovine serum albumin and folic acid to GNPs was investigated by infrared (IR) spectroscopy. Toxicity was measured by the MTT method and based on the results, the GNPs’ non-toxic concentration was determined. The effect of targeted synthesized GNPs on their absorption and sensitivity were evaluated on HeLa cells.

The non-toxic concentration of GNPs was 12 μg/ml. Incubation of the cells with this concentration was performed for 2, 4, and 24 hours and it was observed that in 4 hours, the absorption rate of targeted GNPs was about 4 times higher than that of non-targeted GNPs. The radiosensitization ratios of targeted and non-targeted GNPs in the studied cancer cells relative to the control group (without NPs) exposed to 6 MV photon radiation were 1.32±0.02 and 1.19±0.02, respectively.

The use of bovine serum albumin linker to target GNPs has a significant effect on increasing the absorption of GNPs and the effect of ionizing radiation on HeLa cells under 6 MV photon beams.

In this study, in order to reduce the effects of metal artifacts caused by metal objects in CT scan images of the mouth area, we investigated the quality parameters of head and neck CT scan images of patients before and after the presence of artifacts and evaluated the changes in quality image parameters to improve the quality of radiotherapy after modifying the images. For this purpose, first, we provided CT scan images of 20 patients with head and neck cancers with and without metal objects in the mouth area and compared the absorbed dose in patients with and without metal objects. Then, in order to prevent the destructive effects of images with artifacts in diagnosis and treatment process in radiotherapy, we created modified images by two different neural network models and evaluated the performance of neural networks by image quality parameters to find the effective neural network. By generative adversarial neural network, in some places around salivary glands and teeth with metal, up to 94% improvement has been achieved in image quality metrics, which is up to 70% better than the convolutional neural network. This study can be done to improve the quality of treatment in radiotherapy on patients with different types of cancer, especially with metal prostheses, in order to improve the quality of CT scan images for better diagnosis and contouring of the therapeutic area and reduce the dose received by patients through radiotherapy.

The considerable growth of 3D printing technology in recent years has led to the application of this emerging technology in many medical fields, in which recently performed studies have shown the special importance of this technology which can enhance the results of the treatment method. Since, surgery is one of the main modalities to treat patients, the advent of 3D printing technology in surgery and the creation of different patient organs with 3D printers, improve the surgeon's performance. Hence, the accuracy and quality of the surgery can be enhanced. The aim of this study was to review the current statues and the applications of the 3D printing technology in surgery.

By searching the indexed articles in Persian and Latin databases, Scopus, PubMed, Science direct, Scholar, 34 studies were reviewed.

3D printing applications in surgery: Generally, the ability to generate a physical object with complex structures from a digital model has been introduced as the 3D printing technology which offers many advantages over the traditional manufacturing. The most important advantage of 3D printing technology is the ability to produce objects based on individual needs in which can reduce the costs of their production. Furthermore, complex preoperative procedures can be practiced. In other words, 3D printed models allow physicians to become familiar with medical procedures which possible problems created during the operation, can be identified before the operation. This modern technology generally includes three main steps to generate 3D objects from imaging data. The first step is the acquisition of image data. Then, the interest region is extracted which is termed as the segmentation. Finally, the digital data is transferred to the 3D printers to produce the 3D object.  For 3D model production, printer selection highly depends on speed, accuracy, cost, and availability of the printing materials. Recent advances in 3D printing technology have made it possible to use various biocompatible materials such as titanium and degradable polyesters to produce 3D models. Complex surgeries require more precise visual understanding before the surgery to ensure about the success of the treatment. In this regard, 3D printing technology can be a promising way to produce faster and cheaper models. In addition, this modern technology enables producers to produce highly specialized products for a wide range of patient organs. Applying a physical model results in better performance and greater visual perception about the desired treatment area, which can significantly reduce the side effects during surgery. Since a large contribution of the surgical process can be performed outside the operating room hence, 3D printed models can reduce the operation time. In fact, before the operation, surgeons will have enough time to make decisions, evaluate solutions and focus on other key elements during the operation. So, based on the basic role of 3D printing technology in surgery, the purpose of the present review is to investigate the current state of 3D printing technology and its clinical application in surgery for the construction of various 3D organs via medical imaging data. In this paper, some applications such as maxillofacial, spinal, liver, etc., are briefly discussed. Maxilla-facial and cranial facial reconstruction are the complex procedure which have been one of the first and most proven applications of 3D printing in the field of surgery to correct the facial deformities after the tumor resection. In this method with the application of 3D printers, at first, a 3D model of the desired anatomy is prepared to reduce a significant amount of time for linking the titanium plates to transplant adjacent bones (while the patient is anesthetized). Also, the production of titanium implants using the 3D printers will result in a very precise fit with the target tissue, the risks of maxillofacial surgery can be reduced.The use of 3D printing applications before or during complex surgeries like congenital heart defects has been reported in several studies. Since, acquiring to the real anatomical structures in patients with complex congenital defects, are sometimes unpredictable, treatment planning and surgical decision-making require a thorough understanding of three-dimensional anatomy. Therefore, the 3D printing technique, as a widely used method in all medical fields can overcome the defects of common preoperative imaging, especially in cardiovascular surgery.The other application of 3D printing technology includes spinal surgery in which due to the complex anatomy of the spine and the delicate nature of the surrounding structures, 3D printers will improve preoperative planning and increase the accuracy during the surgery.Liver surgery can be another suitable candidate for performing 3D printing technology to create 3D printing models. The two main applications of 3D printing technology in this field include training or necessary planning for surgery and liver functional cell printing through bio-printing technology that can be used in the study of liver disease and pharmaceutical research.Renal tumor resection is the other example of 3D printing applications in which 3D models have an exclusive role to enhance the accuracy of renal surgery. The 3D printed models can accurately display three-dimensional spatial relationships between different anatomical and pathological structures. Three-dimensional printed kidney models may also facilitate interdisciplinary communication and decision-making about the management of patients undergoing renal surgery.  In the field of renal surgeries, employing of 3D printed models plays a specific performance to train young surgeons which consequently increases the practical skills of surgeons which can accurately visualize the anatomical and morphological relationship compared to volumetric imaging.The obtained results of performed studies in the field of 3D printing show the potential significance of this technology in surgery which can lead to improvement of therapeutic outcomes. Since the printed models by 3D printing technology have an appropriate fit to the anatomy, the use of these models can reduce the associated errors during surgery.It is worth noting that despite the valuable advantages of this technology, some disadvantages such as limited printing size and costly printing process can be discussed which many studies try to address the deficiency of 3D printing technology in clinical applications. The cost of 3D printed models varies according to the type of performed printing method and applicable software which requires specialized users. The main mentioned costs for 3D model creation include hardware, software, and printed materials. In the future, the production costs of 3D models would be likely reduced in which the use of 3D models would become more traditional in common clinical operation. The 3D printed physical models are based on medical imaging which are prone to errors during the imaging procedures. Hence, increasing the accuracy of creating printed models requires improving the clinical imaging methods. Generally, with the advances in this modern technology, faster, cheaper, and more accurate models can be produced.

Breast cancer is considered as one of the main causes of cancer death in women. Early diagnosis and treatment, especially by modern technologies play major roles in management of breast cancer. Radiation therapy is known as one of the main treatment options for breast cancer. Nowadays, 3D printing technology is also used to rapidly construct objects with high quality. Many studies have shown the positive effects of this technology on the results of cancer radiation therapy. The aim of this study was to review the application of 3D printing technology in treatment of breast cancer by mega voltage electron and photon beams, including bolus, applicators, immobilizer devices, and compensators. Creating personalized treatment devices by 3D printing technology reduces treatment errors, therefore, the prescribed dose is increased in the treatment area and subsequently improves treatment outcomes. In spite of the valuable benefits of this technology, there are some disadvantages such as size limitations and the number of materials used for printing. Indeed, recent studies are trying to fix the shortcomings of 3D printing technologies in clinical applications.

Nowadays, 3D printing technology is used for rapid prototyping of high quality objects, so that this technology plays an important role in the modern fields of medicine, especially in surgery, radiation therapy, radiology and etc. Generally, the process of creating a physical object from a digital model is considered as a simple definition of 3D printing. Compared to conventional printers, 3D printers create a physical 3D model of the desire target. Creation of a model by 3D printer requires a digital 3D model which can be obtained by scanning a set of 3D images or drawing them using CAD design software, as well as using computed tomography (CT) data or magnetic resonance imaging (MRI) imaging. Then, this digital model is sent to the printer and finally, a 3D layer-by-layer model is created. The whole mentioned process is called as fast prototyping or 3D printing. Since, personal radiotherapy is introduced as one of the main modality for the treatment and management of various cancers, requires precise details to improve the performance of the employed modality. Todays, 3D printers are able to produce a realistic model of complex geometries, so 3D printing technology can be a complementary and promising method for treating patients and making specific equipment for them, especially in radiotherapy. The dramatic growth of 3D printing technology in various fields of medicine in recent years, has led to the introduction of new applications of this technology in these fields, so that the importance of this technology in improving the performance of treatment modalities, has been reported in several recent studies. The use of 3D printing technology will reduce the cost of radiation therapy which as a promising method, can enhance the efficacy of employed modality. Performed studies have shown that 3D printing technology is a fast, practical and inexpensive method for delivering a uniform dose to the target volume while protecting healthy tissues in the radiation field. Furthermore, this technology reduces patient discomfort which can provide specific radiotherapy devices to each patient. The employment of 3D printed devices, based on the anatomical features of each patient in radiotherapy, such as bolus and fixed devices can reduce daily uncertainty (in radiotherapy) and also increase the accuracy of treatment. 3D printing technology enables users to employ various materials for better performance of radiotherapy method. So far, several materials have been used and evaluated to produce the desired 3D object via the 3D printing technology, including polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol (PETG), thermoplastic elastomers (TPE), Polyamide (PA, also called nylon), thermoplastic polyurethane (TPU), and polyvinyl acetate. The accuracy and efficacy of 3D printing technology highly depends on the performed materials for creation of the 3D objects. PLA and ABS have been introduced as the most common performed materials in 3D printing technology. PLA is a type of odorless plastic polymer which can be used in many industries, such as biodegradable implants and food packaging. ABS is more resistant than PLA which can tolerate the high temperatures. PA material is flexible, very cohesive and very resistant as a plastic polymer as well. The most common use of TPE has been introduced in the construction of flexible objects which with the use of this material objects can be created in a short time. PETG materials are a combination of PET and glycols with different concentrations. All the mentioned materials are available in the form of filaments with diameters of 1.75 mm and 3 mm. Performed investigations in our present work have shown that patient-specific devices can be generated from volumetric CT images or MRI data by 3D printing. In fact, 3D printing technology has great potential for improving the accuracy and efficiency of personal radiotherapy which this technology offers a relatively inexpensive and effective method to produce devices based on individual anatomy in radiotherapy. The practical usage of the 3D printing technology in radiation therapy can improve treatment outcomes and reduce treatment error which the weaknesses of traditional radiotherapy methods can be eliminated. Due to the advantages of this new method, the main aim of present review is to introduce some applications of 3D printing technology in radiotherapy, as a new approach in this therapeutic method, such as bolus, phantoms, brachytherapy applicators, filters, patient fixation devices, compensatory blocks and grid blocks. In most of the performed studies, the advent of 3D printing technology in the field of radiotherapy has been reported as a cost-effective and accessible method so that more practical parts can be produced. Performed studies also showed that the favorable agreement between the printed model in terms of matching the unique body geometry of each patient will reduce the side effects of radiation to healthy tissues..

Today، a CT scan examination play an important role in disease diagnosis and thus allocates a significant dose of medical X-ray examinations. One of the important principles in the use of ionizing radiations is to observe radiation protection principles. Evaluating patient''s absorbed dose and implementing the strategies for reducing dose are prior in safety issues. To achieve this purpose، sufficient studies should be performed in this regard. Therefore، patient''s absorbed dose and the factors affecting have been studied in this research. This study aims to present and develop an acceptable level of absorbed dose in CT scan examinations.

Diagnostic reference dose level in the adult age group (older than 15 years) has been studied in eleven CT scan centers in Tehran. For this purpose، CT scan examinations prevalent in above-mentioned centers were chosen and Weighted Computed Tomography dose index (CTDIw) and dose length product (DLP) parameters were studied. Standard phantoms with 16 and 32 diameters of Polymethylmethacrylate (PMMA) origin have been used in the centers for CT scan calibration process. CTDIw third quartile has been considered as the diagnostic reference dose level (DRL).

Rate of diagnostic reference dose in the adult age group (older than 15 years) for the head، sinus، lungs، abdomen and pelvis are 50. 87، 38. 27، 8. 05 and 9. 11 mg، respectively. Dose measurements made in this survey have been used to set up local DRLs and can be used as a template for national DRLs.

Value of diagnostic reference dose for the head examinations is more than the other parts and diagnostic reference dose in Tehran city in the Adult age group and the protocols compared is less than national reference dose.