Staykova, Vanya, Kirby, Michael 
ORCID: 0000-0001-9765-5641, Misson-Yates, Sarah and Eaton, David
(2023)
Spatially fractionated radiation therapy with photon beams-literature review.
[Poster]
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Abstract
Abstract: Spatially fractionated radiation therapy with photon beams -literature review Introduction: Spatially fractionated radiation therapy (SFRT) is a promising approach for treatment of bulky tumours (>5-6cm diameter) which usually have a poor blood supply and hypoxia, leading to protection against apoptosis. In addition, an unacceptable RT related toxicity is predicted with a high dose RT or SBRT which limits the use of traditional SBRT or high dose radiotherapy. Using advanced IMRT/VMAT, IGRT and inverse planning, intentionally high heterogeneous dose distributions are created in the pattern of lattice of multiple spherical vertices of high dose (peaks) and regions of low doses with a typical dose ratio 100%/30%, a technique known as Lattice RT (LRT), a subcategory of SFRT. These highly heterogeneous dose distributions are the basis for the SFRT radiobiological rationale: radiation induced bystander effect, ablative effect, vascular compromise, overcoming hypoxia, immunostimulatory. Purpose: To review SFRT/LRT clinical results and various planning and plan evaluation SFRT/LRT methodologies with photon beams from clinical radiotherapy systems. Methods: A search in the Medline database (PubMed search tool) using the terms: “Lattice SBRT”, "Lattice Radiation Therapy/Radiotherapy”, “Spatially fractionated radiation therapy/radiotherapy” “GRID radiation therapy/radiotherapy” was conducted. Results: The search returned 115 results, 39 results were identified as SFRT with photon beams, 13 - SFRT with proton, electron or ion beams, and 21 publications were describing the 2D predecessor of LRT, the GRID therapy. There is intensive growth of ~30% in the number of SFRT publications in the last 12 months. Hundreds of patients, mainly in three centres in the USA, with H&N, sarcoma, Gynae and Lung disease sites were treated with Lattice SBRT. The majority of clinical publications on SFRT are case reports and retrospective studies [1, 2], however the initial results from a phase I prospective study with 20 patients (22 tumours) demonstrate no likely treatment-associated grade 3 + toxicity (90-day period) and one case of grade 4 toxicity (possibly associated with LTR) [3]. An ongoing phase II clinical trial will evaluate late safety and efficacy of Lattice SBRT. Two main lattice patterns & creation approaches were identified: a regular diamond- shaped lattice pattern (1.5cm spherical vertices, 6cm center-to-center) and an irregular placement of the high dose vertices to fit induvial GTV in terms of shape, volume, location [4, 5]. Dose heterogeneity is the most important dosimetric characteristic to be defined and reported for plan evaluation but no consensus on the metrics have been reached. Conclusion: SFRT/LRT planning and plan evaluation methodologies and clinical studies for LRT efficacy are very dynamic and developing areas in RT, having the potential to become a main stream RT approach in the near future.
| Item Type: | Poster |
|---|---|
| Divisions: | Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Population Health Faculty of Health and Life Sciences > Institute of Population Health > School of Health Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 31 Mar 2023 07:29 |
| Last Modified: | 31 Mar 2023 07:29 |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3169369 |
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