Particle therapy for cancers:a new weapon in radiation therapy

Particle irradiation started to draw attention in the past decade and has now become a hotspot in the radiation oncology community.This article reviews the most advanced developments in particle irradiation,focusing on the characteristics of proton and carbon ions in radiation physics and radiobiology.The Bragg peak of physical dose distribution causes proton and carbon beams to optimally meet the requirement for cancer irradiation because the Bragg peak permits the accurate concentration of the dose on the tumor,thus sparing the adjacent normal tissues.Moreover,carbon ion has more radiobiological benefits than photon and proton beams.These benefits include stronger sterilization effects on intrinsic radio-resistant tumors and more effective killing of hypoxic,G0,and S phase cells.Compared with the most advanced radiation techniques using photon,such as three-dimensional conformal radiation therapy and intensity-modulated radiation therapy,proton therapy has yielded more promising outcomes in local control and survival for head and neck cancers,prostate carcinoma,and pediatric cancers.Carbon therapy in Japan showed even more promising results than proton therapy.The local controls and overall survivals were as good as that treated by surgery in early stages of non-small cell lung cancer,hepatocellular carcinoma,prostate carcinoma,and head and neck cancers,especially for such highly resistant tumors as melanoma.The non-invasive nature of particle therapy affords more patients with chances to receive and benefit from treatment.Particle therapy is gradually getting attention from the oncology community.However,the cost of particle therapy facilities has limited the worldwide use of this technology.

The role of radiation therapy and particle therapy in renal cell carcinoma: current evidence and future perspectives

For both primary and metastatic renal cell carcinoma(RCC),treatment with stereotactic body radiotherapy(SBRT)has found its way into clinical practice.Being a non-invasive outpatient procedure,SBRT requires only a few visits to the radiation department and may be of interest for the elderly or,in the case of primary RCC,for patients who are not considered surgical candidates due to technical limitations,medical comorbidities,or in the event that the maintenance of kidney function is compromised.In the treatment landscape of oligometastatic RCC,SBRT shows promise in eradicating metastatic disease and delaying the initiation of systemic treatment.Technical advancements in the planning and administration of radiation treatment and improvements in movement management allow irradiating the tumor and/or metastatic lesions with very high doses in few fractions while maximally sparing the surrounding organs at risk,thus minimizing toxicity.In that context,the increasing availability of particle therapy,such as proton beam radiotherapy or carbon ion radiotherapy,could further optimize the delivery of radiation treatment in order to reduce toxicity and improve outcome.

Comparison between 4D robust optimization methods for carbon-ion treatment planning

Intensity-modulated particle therapy(IMPT)with carbon ions is comparatively susceptible to various uncertainties caused by breathing motion,including range,setup,and target positioning uncertainties.To determine relative biological effectiveness-weighted dose(RWD)distributions that are resilient to these uncertainties,the reference phase-based four-dimensional(4D)robust optimization(RP-4DRO)and each phase-based 4D robust optimization(EP-4DRO)method in carbon-ion IMPT treatment planning were evaluated and compared.Based on RWD distributions,4DRO methods were compared with 4D conventional optimization using planning target volume(PTV)margins(PTV-based optimization)to assess the effectiveness of the robust optimization methods.Carbon-ion IMPT treatment planning was conducted in a cohort of five lung cancer patients.The results indicated that the EP-4DRO method provided better robustness(P=0.080)and improved plan quality(P=0.225)for the clinical target volume(CTV)in the individual respiratory phase when compared with the PTV-based optimization.Compared with the PTV-based optimization,the RP-4DRO method ensured the robustness(P=0.022)of the dose distributions in the reference breathing phase,albeit with a slight sacrifice of the target coverage(P=0.450).Both 4DRO methods successfully maintained the doses delivered to the organs at risk(OARs)below tolerable levels,which were lower than the doses in the PTV-based optimization(P<0.05).Furthermore,the RP-4DRO method exhibited significantly superior performance when compared with the EP-4DRO method in enhancing overall OAR sparing in either the individual respiratory phase or reference respiratory phase(P<0.05).In general,both 4DRO methods outperformed the PTV-based optimization in terms of OAR sparing and robustness.

Emerging radiotherapy technologies and trends in nasopharyngeal cancer

AbTechnology has always driven advances in radiotherapy treatment.In this review,we describe the main technological advances in radiotherapy over the past decades for the treatment of nasopharyngeal cancer(NPC)and highlight some of the pressing issues and challenges that remain.We aim to identify emerging trends in radiation medicine.These include advances in personalized medicine and advanced imaging modalities,standardization of planning and delineation,assessment of treatment response and adaptive re-planning,impact of particle therapy,and role of artificial intelligence or automation in clinical care.In conclusion,we expect significant improvement in the therapeutic ratio of radiotherapy treatment for NPC over the next decade.

Technical commissioning of the spot scanning system in Shanghai Proton Therapy Facility

Background In the field of particle therapy,the method of pencil beam scanning is of great potential for clinical application,now and in the future.Purpose The authors made strong effort to develop a spot scanning system for Shanghai Proton Therapy Facility.Design parameters and basic layout of the system are introduced.Methods Functionalities and specifications of crucial devices are described in detail.Most of the devices in the system were designed in house by the authors themselves,including scanning nozzle,scanning magnets and their power supplies,beam monitors,irradiation control modules and safety interlock modules.During the technical commissioning stage in the fix beam room,the spot scanning system was tested and verified.Results Under conditions of the maximum dose rate and minimum dose rate,a)repeatability of the single spot dose is less than±0.1%;b)nonlinearity of the single spot dose is less than±0.1%;c)FWHM for spot size in air at isocenter varies from 8mm to 12mm for full energy,consistent with the design values;d)lateral dose distribution achieves a flatness of less than 2%for multiple proton energies.Conclusion According to the results of technical commissioning,the spot scanning system is capable of producing a pre-scribed 3D dose distribution for target tumor successfully.