Shielding performance of six different types of concrete in proton therapy room / 中国辐射卫生

@#<b>Objective</b> To study the dose level of proton beams outside the main shield of the 230 MeV proton therapy room with six different types of concrete as the main wall, and to obtain the shielding performance of six different types of concrete. <b>Methods</b> The FLUKA program was used to build a calculation model, and different concrete compositions were introduced into the FLUKA program to simulate the change in ambient dose equivalent rate of the focus with concrete thickness under 230 MeV proton beam irradiation. The transmission curves of six different types of concrete were fitted to obtain shielding performance parameters. <b>Results</b> On the condition that the 230 MeV proton beam irradiated to the water target in 90° direction and the concrete thickness exceeded 40 cm, the proton beam was exponentially decayed for six different types of concrete, and the fitted decay curves had a <i>R</i>² of > 0.99. The linear attenuation coefficients for normal concrete, barite concrete, magnetite concrete, limonite concrete, phosphorite concrete, and ferrosilicate concrete were 0.0148 cm⁻¹, 0.0172 cm⁻¹, 0.0196 cm⁻¹, 0.0219 cm⁻¹, 0.0256 cm⁻¹, and 0.0290 cm⁻¹, respectively. <b>Conclusion</b> The composition and proportion of elements in concrete materials directly affect the shielding ability of concrete against proton beams to a large extent, and the shielding performance of six different types of concrete against proton beams varies greatly. Therefore, shielding materials for the proton therapy room should be selected by a comprehensive consideration of the material compositions and shielding performance of concrete, the difficulty of construction, and construction cost.

Implementation of meta-analysis approach, comparing conventional radiotherapy, and proton beam therapy treating head and neck cancer

Introduction: Radiation therapy is commonly used in the treatment of head and neck cancer in both the definitive and postoperative settings. Proton therapy, due to its intrinsic physical properties, has the ability to reduce the integral dose delivered to the patients while maintaining highly conformal target coverage Materials and Methods:.A literature search was performed on scientific databases, and Preferred Reporting Items for Meta-Analyses guidelines were followed to compute results. Only original studies were selected. Selected studies were used to extract some proposed data for comparison, dosimetry, site, complications, and survival. Results: Proton beam therapy technology can be used against the conventional radiotherapy and shows satisfactory results. Yet conventional therapy is not less advantageous considering the amount of work available for any cross interpretations. Conclusion: Comparative preplanning could be beneficial considering multiple therapies for ruling out the best treatment outcomes that could be expected

Radiation-induced Myositis after Proton Beam Therapy to Huge Hepatocellular Carcinoma

Proton beam therapy (PBT) is one of the advances in radiotherapy techniques, which enables dose escalation with lower probability of radiation-induced liver or gastrointestinal injuries. However, the chest wall proximal to the tumor can be affected by high dose irradiation. Here, we report on a 58-year-old male patient who presented with huge hepatocellular carcinoma, received treatment with transarterial chemoembolization and PBT, and developed severe chest wall pain due to radiation-induced myositis. The patient's symptoms were controlled by oral steroids.

Effects on Periocular Tissues after Proton Beam Radiation Therapy for Intraocular Tumors

BACKGROUND: To present our experience on orbital and periorbital tissue changes after proton beam radiation therapy (PBRT) in patients with intraocular tumors, apart from treatment outcomes and disease control. METHODS: Medical records of 6 patients with intraocular tumors who had been treated with PBRT and referred to oculoplasty clinics of two medical centers (Seoul National University Hospital and Seoul Metropolitan Government-Seoul National University Boramae Medical Center) from October 2007 to September 2014 were retrospectively reviewed. The types of adverse effects associated with PBRT, their management, and progression were analyzed. In anophthalmic patients who eventually underwent enucleation after PBRT due to disease progression, orbital volume (OV) was assessed from magnetic resonance (MR) images using the Pinnacle3 program. RESULTS: Among the six patients with PBRT history, three had uveal melanoma, and three children had retinoblastoma. Two eyes were treated with PBRT only, while the other four eyes ultimately underwent enucleation. Two eyes with PBRT only suffered from radiation dermatitis and intractable epiphora due to canaliculitis or punctal obstruction. All four anophthalmic patients showed severe enophthalmic features with periorbital hollowness. OV analysis showed that the difference between both orbits was less than 0.1 cm before enucleation, but increased to more than 2 cm3 after enucleation. CONCLUSION: PBRT for intraocular tumors can induce various orbital and periorbital tissue changes. More specifically, when enucleation is performed after PBRT due to disease progression, significant enophthalmos and OV decrease can develop and can cause poor facial cosmesis as treatment sequelae.

Radiation Therapy against Pediatric Malignant Central Nervous System Tumors : Embryonal Tumors and Proton Beam Therapy

Radiation therapy is highly effective for the management of pediatric malignant central nervous system (CNS) tumors including embryonal tumors. With the increment of long-term survivors from malignant CNS tumors, the radiation-related toxicities have become a major concern and we need to improve the treatment strategies to reduce the late complications without compromising the treatment outcomes. One of such strategies is to reduce the radiation dose to craniospinal axis or radiation volume and to avoid or defer radiation therapy until after the age of three. Another strategy is using particle beam therapy such as proton beams instead of photon beams. Proton beams have distinct physiologic advantages over photon beams and greater precision in radiation delivery to the tumor while preserving the surrounding healthy tissues. In this review, I provide the treatment principles of pediatric CNS embryonal tumors and the strategic improvements of radiation therapy to reduce treatment-related late toxicities, and finally introduce the increasing availability of proton beam therapy for pediatric CNS embryonal tumors compared with photon beam therapy.

A Case of Hepatocellular Carcinoma Treated by Proton Beam Therapy as 1st Choice

Although first-line treatment option for single, small sized hepatocellular carcinoma in patients with preserved liver function and good performance status is resection or ablation, sometimes these modalities cannot be applied for variable reasons. For them, alternative options such as transarterial chemoeombolization, ethanol injection, and external radiation therapy can be considered, with variable success rates. Herein, we describe 45 year-old male who presented with a single small tumor located at caudate lobe. After multi-disciplinary discussion, the patient was treated with proton beam therapy, which resulted in favorable treatment outcome.

Radiation Therapy against Pediatric Malignant Central Nervous System Tumors : Embryonal Tumors and Proton Beam Therapy

Radiation therapy is highly effective for the management of pediatric malignant central nervous system (CNS) tumors including embryonal tumors. With the increment of long-term survivors from malignant CNS tumors, the radiation-related toxicities have become a major concern and we need to improve the treatment strategies to reduce the late complications without compromising the treatment outcomes. One of such strategies is to reduce the radiation dose to craniospinal axis or radiation volume and to avoid or defer radiation therapy until after the age of three. Another strategy is using particle beam therapy such as proton beams instead of photon beams. Proton beams have distinct physiologic advantages over photon beams and greater precision in radiation delivery to the tumor while preserving the surrounding healthy tissues. In this review, I provide the treatment principles of pediatric CNS embryonal tumors and the strategic improvements of radiation therapy to reduce treatment-related late toxicities, and finally introduce the increasing availability of proton beam therapy for pediatric CNS embryonal tumors compared with photon beam therapy.

Understanding the Treatment Strategies of Intracranial Germ Cell Tumors: Focusing on Radiotherapy

Intracranial germ cell tumors (ICGCT) occur in 2-11% of children with brain tumors between 0-19 years of age. For treatment of germinoma, relatively low radiation doses with or without chemotherapy show excellent 10 year survival rate of 80-100%. Past studies showed that neoadjuvant chemotherapy combined with focal radiotherapy resulted in unacceptably high rates of periventricular tumor recurrence. The use of generous radiation volume which covers the whole ventricular space with later boost treatment to primary site is considered as standard treatment of intracranial germinomas. For non-germinomatous germ cell tumors (NGGCT), 10-year overall survival rate is still much inferior than that of intracranial germinoma despite intensive chemotherapy and high-dose radiotherapy. Craniospinal radiotherapy combined with cisplatin-based chemotherapy provides the best treatment outcome for NGGCT; 60-70% of overall survival rate. There is a debate on the surgical role whether surgery can contribute to improved treatment outcome of NGGCT when added to combined chemoradiotherapy. Because higher dose of radiotherapy is required for treatment of NGGCT than for germinoma, it is tested whether whole ventricular irradiation can replace craniospinal irradiation in intermediate risk group of NGGCT to minimize radiation-related late toxicity in the recent studies. To minimize the treatment-related neural deficit and late sequelae while maintaining long-term survival rate of ICGCT patients, optimized administration of chemotherapy and radiotherapy should be selected. Use of technically upgraded radiotherapy modalities such as intensity-modulated radiotherapy or proton beam therapy is expected to bring an improved neurocognitive outcome with longitudinal assessment of the patients.

The first private-hospital based proton therapy center in Korea; status of the Proton Therapy Center at Samsung Medical Center

PURPOSE: The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. MATERIALS AND METHODS: The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. RESULTS: The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. CONCLUSION: The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015.

Proton Beam Radiotherapy for Pediatric Gliomas: Early Outcomes and Dose Comparison / 임상소아혈액종양

BACKGROUND: Proton beam radiotherapy (PBT) has shown to provide high radiation dose to tumors and to save surrounding normal tissues because of its physical characteristics, Bragg peak. In the current study, we report the early outcomes for pediatric patients with intracranial gliomas treated with PBT and compared PBT plan (pencil beam scanning and double scattering) with intensity modulated radiotherapy (IMRT) plan and three dimensional-conformal radiotherapy (3D-CRT) plan.METHODS: Clinical data from 18 consecutive children with intracranial gliomas who underwent PBT from May 2007 to April 2012 was collected. The median follow-up duration was 16 months (range 6-69).RESULTS: There were 9 patients with brain stem glioma, 2 patients with optic pathway glioma, 2 patients with low grade glioma (LGG), 2 patients with anaplastic astrocytoma (AA) and 3 patients with glioblastoma multiforme (GBM). The median overall survival for patients with brain stem glioma was 11 months. Patients with optic pathway glioma, LGG or AA were all alive without progression except one patient. Among patients with GBM, one patient had no evidence of disease 25 months after PBT. When PBT plan was compared to those of IMRT and 3D-CRT for patients with LGG or AA and one patient with brain stem glioma by DVH analysis, PBT showed better sparing effect on normal tissue compared to IMRT and 3D-CRT, especially in low dose area.CONCLUSION: PBT could be delivered safely and effectively to pediatric patients with gliomas. For confirming the clinical benefits of PBT, further follow-up is necessary.

Proton Beam Radiotherapy for Pediatric Gliomas: Early Outcomes and Dose Comparison / 임상소아혈액종양

BACKGROUND: Proton beam radiotherapy (PBT) has shown to provide high radiation dose to tumors and to save surrounding normal tissues because of its physical characteristics, Bragg peak. In the current study, we report the early outcomes for pediatric patients with intracranial gliomas treated with PBT and compared PBT plan (pencil beam scanning and double scattering) with intensity modulated radiotherapy (IMRT) plan and three dimensional-conformal radiotherapy (3D-CRT) plan. METHODS: Clinical data from 18 consecutive children with intracranial gliomas who underwent PBT from May 2007 to April 2012 was collected. The median follow-up duration was 16 months (range 6-69). RESULTS: There were 9 patients with brain stem glioma, 2 patients with optic pathway glioma, 2 patients with low grade glioma (LGG), 2 patients with anaplastic astrocytoma (AA) and 3 patients with glioblastoma multiforme (GBM). The median overall survival for patients with brain stem glioma was 11 months. Patients with optic pathway glioma, LGG or AA were all alive without progression except one patient. Among patients with GBM, one patient had no evidence of disease 25 months after PBT. When PBT plan was compared to those of IMRT and 3D-CRT for patients with LGG or AA and one patient with brain stem glioma by DVH analysis, PBT showed better sparing effect on normal tissue compared to IMRT and 3D-CRT, especially in low dose area. CONCLUSION: PBT could be delivered safely and effectively to pediatric patients with gliomas. For confirming the clinical benefits of PBT, further follow-up is necessary.

Curent advances and stretegies for reducing the side effects of radiation therapies used for various types of cancers.

Cancer originates from the abnormal expression or activation of positive regulators and functional suppression of negative regulators. The World Health Organization (WHO) estimates that 84 million people will die of cancer between 2005 and 2015 without intervention. Research suggests that one-third of cancer deaths can be avoided through prevention. Major cancer treatment modalities are surgery, radiation therapy and chemotherapy. Radiation therapy is an important cancer treatment method and is used for approximately 50% of all cancer patients with varying success. Therapy uses high-energy waves or particles to destroy cancer cells. It can be used basically for three main reasons: to achieve high radiation dose into tumors; minimizing dose into surrounding normal tissues; to avoid complications as far as possible. The recent advances in this treatment method have led to the improvement in cancer death statistics. It can also be combined with surgery or chemotherapy for better results. This review covers general applications, various side effects/agents and factors affecting to get rid of these effects and strategies to improve radiation therapy.

Research of Tumor Cells Atypia Based on Perspective Imaging of Intense Laser Proton / 中国医学物理学杂志

Objective: To research the application of perspective imaging of intense laser proton beam in tumor cells, experi-ments are carried out on an ultra-intense picosecond pulsed laser facility, and the results of perspective imaging on biological samples by high energy proton beam, which is excitated among the interaction of picosecond laser with solid target, is showed. Methods: The laser energy is 12 J, the pulse width of laser is 1.5 ps, the laser focal spot diameter is 15 μm, the coefficientf or the off-axis paraboloid lens is 1.5. The target used in the experiment is made by coating a CH film with 1 μm on the back of the 15 pan-thick Cu. The distance between the proton source (laser spot) and the ant sample is 7 mm (i.e. the object distance), the distance between the sample and the RC film is 63 mm (i.e. the image distance). The detector is a stack of RCF or CR-39 films. Results: The ant is taken as the sample, a high energy proton beam, which is excitated as above on the rear surface of target, makes a 2-dimensional perspective imaging of an ant with high contrast, nanometer spatial resolution and density reso-lution. Conclusions: The result provided possibility of the application of perspective imaging of intense laser proton beam in tumor cells.

Fabrication and Optimization of a Fiber-optic Dosimeter for Proton Beam Therapy Dosimetry / 의학물리

In this study, we have fabricated a fiber-optic dosimeter for a proton beam therapy dosimetry. We have measured scintillating lights with the various kinds of organic scintillators and selected the BCF-12 as a sensor-tip material due to its highest light output and peak/plateau ratio. To determine the optimum diameter of BCF-12, we have measured scintillating lights according to the energy losses of proton beams in a water phantom. Also, we determined the adequate length of organic scintillator by measuring scintillating lights according to the incident angles of proton beam. Using an optimized fiber-optic dosimeter, we have measured scintillating lights according to the dose rates and monitor units of proton accelerator.