Radiotherapy is currently used in around 50% of cancer treatments and relies on the deposition of energy directly into tumour tissue. Although it is generally effective, some of the deposited energy can adversely affect healthy tissue outside the tumour volume, especially in the case of photon radiation (gamma and X-rays). Improved radiotherapy outcomes can be achieved by employing ion beams due to the characteristic energy deposition curve which culminates in a localised, high radiation dose (in form of a Bragg peak). In addition to ion radiotherapy, novel sensitisers, such as nanoparticles, have shown to locally increase the damaging effect of both photon and ion radiation, when both are applied to the tumour area. Amongst the available nanoparticle systems, gold nanoparticles have become particularly popular due to several advantages: biocompatibility, well-established methods for synthesis in a wide range of sizes, and the possibility of coating of their surface with a large number of different molecules to provide partial control of, for example, surface charge or interaction with serum proteins. This gives a full range of options for design parameter combinations, in which the optimal choice is not always clear, partially due to a lack of understanding of many processes that take place upon irradiation of such complicated systems. In this review, we summarise the mechanisms of action of radiation therapy with photons and ions in the presence and absence of nanoparticles, as well as the influence of some of the core and coating design parameters of nanoparticles on their radiosensitisation capabilities.

/pdf/gold-nanoparticles-for-cancer-radiotherapy-a-review-4atvgy07ry.pdf

Gold nanoparticles for cancer radiotherapy: a review

This review focuses on the radiosensitization strategies that use high-Z nanoparticles. It does not establish an exhaustive list of the works in this field but rather propose constructive criticisms pointing out critical factors that could improve the nano-radiation therapy. Whereas most reviews show the chemists and/or biologists points of view, the present analysis is also seen through the prism of the medical physicist. In particular, we described and evaluated the influence of X-rays energy spectra using a numerical analysis. We observed a lack of standardization in preclinical studies that could partially explain the low number of translation to clinical applications for this innovative therapeutic strategy. Pointing out the critical parameters of high-Z nanoparticles radiosensitization, this review is expected to contribute to a larger preclinical and clinical development.

/pdf/nanoparticles-for-radiation-therapy-enhancement-the-key-2r3gxusf6c.pdf

Nanoparticles for Radiation Therapy Enhancement: the Key Parameters.

An urgent need for early detection and diagnosis of diseases continuously pushes the advancements of imaging modalities and contrast agents. Current challenges remain for fast and detailed imaging of tissue microstructures and lesion characterization that could be achieved via development of nontoxic contrast agents with longer circulation time. Nanoparticle technology offers this possibility. Here, we review nanoparticle-based contrast agents employed in most common biomedical imaging modalities, including fluorescence imaging, MRI, CT, US, PET and SPECT, addressing their structure related features, advantages and limitations. Furthermore, their applications in each imaging modality are also reviewed using commonly studied examples. Future research will investigate multifunctional nanoplatforms to address safety, efficacy and theranostic capabilities. Nanoparticles as imaging contrast agents have promise to greatly benefit clinical practice.

Applications of nanoparticles in biomedical imaging.

Purpose: Flattening filters (FFs) have been considered as an integral part of the treatment head of a medical accelerator for more than 50 years. The reasons for the longstanding use are, however, historical ones. Advanced treatment techniques, such as stereotactic radiotherapy or intensity modulated radiotherapy have stimulated the interest in operating linear accelerators in a flattening filter free (FFF) mode. The current manuscript reviews treatment head physics of FFF beams, describes their characteristics and the resulting potential advantages in their medical use, and closes with an outlook. Methods: A number of dosimetric benefits have been determined for FFF beams, which range from increased dose rate and dose per pulse to favorable output ratio in-air variation with field size, reduced energy variation across the beam, and reduced leakage and out-of-field dose, respectively. Finally, the softer photon spectrum of unflattened beams has implications on imaging strategies and radiation protection. Results: The dosimetric characteristics of FFF beams have an effect on treatment delivery, patient comfort, dose calculation accuracy, beam matching, absorbed dose determination, treatment planning, machine specific quality assurance, imaging, and radiation protection. When considering conventional C-arm linacs in a FFF mode, more studies are needed to specify and quantify the clinical advantages, especially with respect to treatment plan quality and quality assurance. Conclusions: New treatment units are already on the market that operate without a FF or can be operated in a dedicated clinical FFF mode. Due to the convincing arguments of removing the FF, it is expected that more vendors will offer dedicated treatment units for advanced photon beam therapy in the near future. Several aspects related to standardization, dosimetry, treatment planning, and optimization need to be addressed in more detail in order to facilitate the clinical implementation of unflattened beams. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3554643]

https://aapm.onlinelibrary.wiley.com/doi/pdf/10.1118/1.3554643

Current status and future perspective of flattening filter free photon beams

SUMMARY POINTS * 1. What is the motivation for this report? * 1.1. Which procedures are of concern and who is involved? * 1.2. Who has the potential to receive high radiation doses? * 1.3. Lack of training, knowledge, awareness and skills in radiological protection * 1.4. Patient versus occupational radiation doses * 1.5. Fear and overconfidence * 1.6. Training * 1.7. Why this report? * 1.8. References * 2. HEALTH EFFECTS OF IONISING RADIATION * 2.1. Introduction * 2.2. Radiation exposure in context * 2.3. Health effects of ionising radiation * 2.3.1. Tissue reactions * 2.3.2. Stochastic effects * 2.3.3. Individual differences in radiosensitivity * 2.4. References * 3. PATIENT AND OCCUPATIONAL PROTECTION * 3.1 General methods and principles of radiological protection * 3.2. Requirements for the facility * 3.3. Common aspects of patient and occupational protection * 3.3.1. Patient specific factors * 3.3.2. Technique factors * 3.4. Specific aspects of occupational protection * 3.4.1. Shielding * 3.4.2. Individual monitoring * 3.5. References * 4. SPECIFIC CONDITIONS IN CLINICAL PRACTICE * 4.1. Vascular surgery * 4.1.1. Levels of radiation dose * 4.1.2. Radiation dose management * 4.2. Urology * 4.2.1. Levels of radiation dose * 4.2.2. Radiation dose management * 4.3. Orthopaedic surgery * 4.3.1. Levels of radiation dose * 4.3.2. Radiation dose management * 4.4. Obstetrics and gynaecology * 4.4.1. Levels of radiation dose * 4.4.2. Radiation dose management * 4.5. Gastroenterology and hepato-biliary system * 4.5.1. Levels of radiation dose * 4.5.2. Radiation dose management * 4.6. Anaesthetics and pain management * 4.7. Sentinel lymph node biopsy (SLNB) * 4.7.1. Levels of radiation dose * 4.7.2. Radiation dose management * 4.8. References * 5. PREGNANCY AND CHILDREN * 5.1. Patient exposure and pregnancy * 5.2. Guidelines for patients undergoing radiological examinations/procedures at child bearing age * 5.3. Guidelines for patients known to be pregnant * 5.4. Occupational exposure and pregnancy * 5.5. Procedures in children * 5.5.1. Levels of radiation dose * 5.5.2. Radiation dose management * 5.6. References * 6. TRAINING * 6.1. Introduction * 6.2. Curriculum * 6.3. Who should be the trainer? * 6.4. How much training? * 6.5. Recommendations on training * 6.5. References * 7. Recommendations * ANNEX A. DOSE QUANTITIES AND UNITS * A.1. Quantities for assessment of patient doses * A.2. Quantities for occupational dose assessment * A.3. References *

https://journals.sagepub.com/doi/pdf/10.1016/j.icrp.2012.03.001

Radiological Protection in Fluoroscopically Guided Procedures Performed Outside the Imaging Department

https://journals.viamedica.pl/rpor/article/download/73252/53342

Asghar Mesbahi

Papers

A review on gold nanoparticles radiosensitization effect in radiation therapy of cancer

A review on photoneutrons characteristics in radiation therapy with high-energy photon beams.

Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations.

Photon mass attenuation coefficients of a silicon resin loaded with WO 3 , PbO, and Bi 2 O 3 Micro and Nano-particles for radiation shielding

Monte Carlo calculation of Varian 2300C/D Linac photon beam characteristics: a comparison between MCNP4C, GEANT3 and measurements.