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Artificial Intelligence in Radiotherapy
Published in P. Kaliraj, T. Devi, Artificial Intelligence Theory, Models, and Applications, 2021
Radiotherapy (RT) is considered to be an effective modality to treat 48.3% of the cancer patients with all types of cancer using RT alone or in combination with surgery or chemotherapy. Even though it is a life-saving technology, it is not accessible to all people who are in different geographical regions, below the poverty line, etc. The field of RT has been developed enormously over a century. It uses ionizing radiations such as photons (X and gamma rays), electrons, protons, etc. to kill tumor cells by protecting surrounding normal structures. It is broadly classified into (i) external beam radiotherapy (EBRT) or teletherapy, where the source of radiation is located a specific distance from the patient, and (ii) brachytherapy, where the radioactive substance is kept close to the patient inside the tumor.
Radiation Therapy and Radiation Safety in Medicine
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
In contrast to external beam radiation therapy, in brachytherapy, a radioactive source can be directly applied to the neighborhood of the tumor, thereby greatly limiting exposure of healthy tissue. This method is mostly used for tumors accessible through natural openings, or those accessible via catheters or implanted needles. Brachytherapy sources are made from nontoxic radioactive materials encased in an ordinary metal and formed into a variety of shapes: needles, small pellets, fine wires, seeds, tubes, needles, etc. (Figure 7.11a); for example, iridium-192, with a half-life of 74 days, is a radioactive metal easily formed into many useful shapes. The radiation source is then implanted into, or placed directly against, the tumor (Figure 7.11b, c). Compared with beam sources, this technique can yield higher doses to the tumor, while limiting the irradiation of nearby healthy tissues. For example, implants can be used in treating cancer of the breast and prostate; brachytherapy can also be used to treat tumors accessible through body openings, such as those in the female reproductive organs.
Current Role of Focal Therapy for Prostate Cancer
Published in Ayman El-Baz, Gyan Pareek, Jasjit S. Suri, Prostate Cancer Imaging, 2018
H. Abraham Chiang, George E. Haleblian
Whole-gland brachytherapy has long been used as a standard of care treatment for clinically localized prostate cancer. Pre-treatment mapping of the prostate is performed with ultrasound, CT or MRI. Once the prostate contour is determined, tissue ablation is achieved by placing radioactive seeds transperineally, typically under TRUS guidance with template. When compared to other standard of care treatments, brachytherapy offers several benefits. It is less invasive than prostatectomy and may be a viable option for patients who are not operative candidates. Furthermore, because the radioactive seeds can be “placed-and-forgotten,” fewer hospital visits are required during treatment compared to external beam radiation. On the other hand, a major shortcoming of brachytherapy is a more pronounced genitourinary side effect profile when compared to radical prostatectomy or external beam radiation. It seems reasonable to deduce, then, that adapting brachytherapy from a whole-gland to focal ablation technique may reduce genitourinary side effects. As a demonstration of technical feasibility, a study has shown that hemi-gland brachytherapy, when compared to whole-gland brachytherapy, resulted in significant reduction in radiation dose to the contralateral gland, as well as to the urethra, neurovascular bundle, and rectum (Laing et al. 2016).
Prostate cancer high dose-rate brachytherapy: review of evidence and current perspectives
Published in Expert Review of Medical Devices, 2018
Sunil W. Dutta, Clayton E. Alonso, Bruce Libby, Timothy N. Showalter
The incidence of prostate cancer has decreased in recent years, due to changes in screening recommendations [1]. This decline mostly affected the diagnosis of stage I and II prostate cancers, patients who already have low prostate cancer‐specific mortality with or without intervention, such as surgery or radiotherapy [2]. The recently published Prostate Testing for Cancer and Treatment (ProtecT) trial randomized patients, 75% of which were low risk, to active monitoring, radical prostatectomy, and external beam radiation (EBRT), and found prostate-cancer-specific mortality to be low irrespective of treatment arm [3]. For patients with low risk disease, EBRT alone has long been an accepted treatment option [4,5]. However, patients with intermediate to high risk disease (prostate-specific antigen (PSA) ≥ 10, Gleason score (GS) ≥ 7, or clinical stage ≥ T2b) have been shown to suffer from poorer long-term biochemical control (freedom from an increasing PSA level) when treated with conventional doses of EBRT alone [6]. Dose escalation trials with EBRT alone have shown improved biochemical control; however, the benefit is accompanied by a higher rate of toxicities, particularly gastrointestinal [7,8]. Brachytherapy has been incorporated into radiotherapy treatment strategies, either alone or in combination with EBRT, as a method to improve biochemical control through dose-escalation without associated increase in toxicities.
Gold nanoparticles: synthesis, application in colon cancer therapy and new approaches - review
Published in Green Chemistry Letters and Reviews, 2021
Karen Magaly Soto, Sandra Mendoza, Jose M. López-Romero, Jose Ramón Gasca-Tirado, Alejandro Manzano-Ramírez
Radiotherapy is the method of ionizing radiation delivered to the tumor via an external beam (X-ray or γ-ray beam) or from an internally placed radiation source (brachytherapy). The exposure can directly induce DNA damage to suppress tumor growth and destroy tumor tissues, on the other hand, directly or indirectly via ionization of molecules (e.g. water) within the cells, generating a cascade of free radicals that conclude in cell death. The limitation of this method is the damage to healthy tissues that occur in parallel; as a result, the dose of radiation administrated must be limited to keep normal tissue toxicities at a tolerable level, the consequent insufficient DNA damage to tumors cannot destroy the tumor, which may result in RT resistance. To evade this limitation, can be use radiosensitizers that concentrate the radiation on the tumor (64,77), one of these sensitizers was the gold nanoparticles for their unique optical characteristics; different mechanism can be proposed for the enhanced effectiveness of radiotherapy by AuNPs: first, the Physical enhanced, based in the high atomic number of the AuNPs (Z = 79) that provides a large X-ray absorption cross-section; therefore can improve the effectiveness by increasing the radiation sensitivity of the tumor and granting the reduce of the radiation dose; second the Chemical sensitization of DNA to radiation, small AuNPs that are capable of nuclear localization and tight electrostatic binding to DNA were recommended to enable full exploitation of the chemical enhancement and finally AuNPs have been shown to induce the formation of Reactive Oxygen Species (ROS). The resulting oxidative stress has emerged as one of the central mechanisms of nanoparticle-induced cytotoxicity (78). Polymeric gold-photoactive nanoparticles (PGPNPs) conjugated with folic acid (FA) was evaluated in combination with radiofrequency therapy against prostate cancer (LNCaP) cells line, there were treated with gold nanoparticles and ionizing radiation, and the synergistic effect of treatment methods was evaluated by colony formation assay (CFA) and Flow cytometry analysis. The results demonstrated that combinatorial therapy of polymeric gold nanoparticles and ionizing radiation at various doses (2, 4, and 6 Gy) had a synergistic effect on survival fraction and apoptotic induction necrotizing cell death (79).