Bioeffect modeling and equieffective dose concepts in radiation oncology--terminology, quantities and units.

The International Commission on Radiation Units and Measurements (ICRU) Report Committee on "Bioeffect Modeling and Biologically Equivalent Dose Concepts in Radiation Therapy" is currently developing a comprehensive and consistent framework for radiobiological effect modeling based on the equieffective dose, EQDX(α/β), a concept encompassing BED and EQD2 as special cases.

Isoeffective dose: a concept for biological weighting of absorbed dose in proton and heavier-ion therapies.

When reporting radiation therapy procedures, International Commission on Radiation Units and Measurements (ICRU) recommends specifying absorbed dose at/in all clinically relevant points and/or volumes. In addition, treatment conditions should be reported as completely as possible in order to allow full understanding and interpretation of the treatment prescription. However, the clinical outcome does not only depend on absorbed dose but also on a number of other factors such as dose per fraction, overall treatment time and radiation quality radiation biology effectiveness (RBE).

Aggressive papillary glioneuronal tumor: case report and literature review.

Papillary glioneuronal tumors (PGNT) are a rare, recently described form of mixed neoplasm composed of glial and neuronal components. PGNT usually occur in children and young adults, and typically demonstrate low-grade pathology, with a low proliferative index of 1-3%. Here we describe a newly diagnosed case of PGNT with a more aggressive phenotype that required irradiation and chemotherapy.

The RBE issues in ion-beam therapy: conclusions of a joint IAEA/ICRU working group regarding quantities and units.

This paper summarises the conclusions of a working group established jointly by the International Atomic Energy Agency (IAEA) and the International Commission on Radiation Units and Measurements (ICRU) to address some of the relative biological effectiveness (RBE) issues encountered in ion-beam therapy. Special emphasis is put on the selection and definition of the involved quantities and units. The isoeffective dose, as introduced here for radiation therapy applications, is the dose that delivered under reference conditions would produce the same clinical effects as the actual treatment in a given system, all other conditions being identical.

p16 gene alterations in locally advanced squamous cell carcinoma of the head and neck.

We previously documented the presence of mutations/deletions in the tumor suppressor gene p16 in squamous cell carcinoma of the head and neck (SCCHN). However, the association of these p16 alterations with clinical outcome is unknown. In this study, RNA was isolated from 19 frozen SCCHN from 19 patients who were previously enrolled in the OSU intensification regimen 2.

Radiobiological rationale and patient selection for high-LET radiation in cancer therapy.

The rationale for introducing ion beams in cancer therapy is the high level of physical selectivity that can be achieved with ions, equal or even better than with proton beams or modern photon techniques, as well as the potential advantage of high-LET radiations for some tumour types and sites. The radiobiological arguments for high-LET radiation in cancer therapy are reviewed: reduction of OER in the case of hypoxic and poorly-reoxygenating tumours, and the lesser importance of repair phenomena which are a problem in controlling repair-proficient photon-resistant tumours. Fast neutrons were the first type of high-LET radiation used clinically, and were often applied under suboptimal technical conditions.

Gamma Knife radiosurgery for intracranial metastatic melanoma: an analysis of survival and prognostic factors.

Objective of this study was to evaluate retrospectively the effectiveness of Gamma Knife radiosurgery for intracranial metastatic melanoma and to identify prognostic factors related to survival. Twenty-six patients with intracranial metastases (72 lesions) from melanoma underwent Gamma Knife radiosurgery. In 14 patients (54%) whole-brain radiotherapy (WBRT) was performed as part of the initial treatment, and in 12 patients (38%) immunotherapy and/or chemotherapy was given after Gamma Knife radiosurgery.

Common challenges and problems in clinical trials of boron neutron capture therapy of brain tumors.

Clinical trials for binary therapies, like boron neutron capture therapy (BNCT), pose a number of unique problems and challenges in design, performance, and interpretation of results. In neutron beam development, different groups use different optimization parameters, resulting in beams being considerably different from each other. The design, development, testing, execution of patient pharmacokinetics and the evaluation of results from these studies differ widely.

Pain in the foot: calcaneal metastasis as the presenting feature of endometrial cancer.

Background: Ninety percent of endometrial cancer cases present with abnormal bleeding. Bone metastasis as the presenting feature is extremely rare.

Case: A 76-year-old woman presented with right heel pain.

Biological weighting of absorbed dose in radiation therapy.

Absorbed dose is a quantity which is scientifically rigorously defined and used to quantify the exposure of biological objects, including humans, to ionising radiation. There is, however, no unique relationship between absorbed dose and induced biological effects. The effects induced by a given absorbed dose to a given biological object depend also on radiation quality and temporal distribution of the irradiation.

Development and calculation of an energy dependent normal brain tissue neutron RBE for evaluating neutron fields for BNCT.

In Boron Neutron Capture Therapy (BNCT) of malignant brain tumors, the energy dependence of a clinically relevant Relative Biological Effectiveness (RBE) for epithermal neutrons, RBE(En), is important in neutron field design. In the first half of this paper, we present the development of an expression for the energy dependent normal-tissue RBE, RBE(En). We then calculate a reasonable estimate for RBE(En) for adult brain tissue.

Long-term follow-up on an intensified treatment regimen for advanced resectable head and neck squamous cell carcinomas.

From February 1993 through July 1994, 37 patients with stage III-IV squamous cell carcinomas of the oral cavity, oropharynx, or hypopharynx (stage II-IV) were registered to a treatment regimen consisting of preoperative continuous infusion cisplatin (80 mg/m2/80 hours) with hyperfractionated external beam radiotherapy (9.1 Gy/7 fractions of 1.3 Gy BID), surgical resection, intraoperative radiotherapy (7.

A comparison of neutron beams for BNCT based on in-phantom neutron field assessment parameters.

In this paper our in-phantom neutron field assessment parameters, T and DTumor, were used to evaluate several neutron sources for use in BNCT. Specifically, neutron fields from The Ohio State University (OSU) Accelerator-Based Neutron Source (ABNS) design, two alternative ABNS designs from the literature (the Al/AIF3-Al2O3 ABNS and the 7LiF-AI2O3 ABNS), a fission-convertor plate concept based on the 500-kW OSU Research Reactor (OSURR), and the Brookhaven Medical Research Reactor (BMRR) facility were evaluated. In order to facilitate a comparison of the various neutron fields, values of T and DTumor were calculated in a 14 cm x 14 cm x 14 cm lucite cube phantom located in the treatment port of each neutron source.

Boron neutron capture therapy of brain tumors: biodistribution, pharmacokinetics, and radiation dosimetry sodium borocaptate in patients with gliomas.

Objective: The purpose of this study was to obtain tumor and normal brain tissue biodistribution data and pharmacokinetic profiles for sodium borocaptate (Na2B12H11SH) (BSH), a drug that has been used clinically in Europe and Japan for boron neutron capture therapy of brain tumors. The study was performed with a group of 25 patients who had preoperative diagnoses of either glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA) and were candidates for debulking surgery. Nineteen of these patients were subsequently shown to have histopathologically confirmed diagnoses of GBM or AA, and they constituted the study population.

Intensification regimen 2 for advanced head and neck squamous cell carcinomas.

Objective: To determine the feasibility, toxicity, and compliance of an intense treatment regimen for patients with advanced, previously untreated, resectable head and neck squamous cell carcinomas.

Design: Prospective, nonrandomized, controlled (phase 1 or 2) clinical trial; median time at risk, 25 months (range, 7 days to 36 months).

Setting: Arthur G.

A challenge for high-precision radiation therapy: the case for hadrons.

Developments in Hadron therapy, i.e., fast neutrons, protons, pions, heavy ions and boron neutron capture therapy are reviewed.

A challenge for high-precision radiation therapy: the case for photons.

The sophistication of Hadron facilities led to major technical and conceptual advances in the treatment immobilization, reproducibility, planning and execution. Some of these developments have had a pivotal impact on conventional treatments, which can now approach the dose localization advantage of protons in the majority of clinical situations. While the biological advantages of neutrons may finally be combined with excellent dose localization in Heavy Ion Facilities, modern surgical or systemic treatment methods may reduce high LET advantages.

Cross-sectional nodal atlas: a tool for the definition of clinical target volumes in three-dimensional radiation therapy planning.

Virtual three-dimensional clinical target volume definition requires the identification of areas suspected of containing microscopic disease (frequently related to nodal stations) on a set of computed tomographic (CT) images, rather than the traditional approach based on anatomic landmarks. This atlas displays the clinically relevant nodal stations and their correlation with normal lymphatic pathways on a set of CT images.

Boron neutron capture therapy of brain tumors: an emerging therapeutic modality.

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10, a stable isotope, is irradiated with low-energy thermal neutrons to yield alpha particles and recoiling lithium-7 nuclei. For BNCT to be successful, a large number of 10B atoms must be localized on or preferably within neoplastic cells, and a sufficient number of thermal neutrons must be absorbed by the 10B atoms to sustain a lethal 10B (n, alpha) lithium-7 reaction. There is a growing interest in using BNCT in combination with surgery to treat patients with high-grade gliomas and possibly metastatic brain tumors.

Boron neutron capture therapy: principles and potential.

This book on the therapeutic applications of neutrons and high-LET radiations in cancer therapy would not have been complete without a review of the present situation of boron neutron capture therapy (BNCT) and a discussion of its future perspectives. BNCT is a special type of high-LET radiation therapy that attempts to achieve a selectivity at the cellular level. The rationale is to incorporate boron atoms selectively in the cancer cells and then bombard those atoms with thermal neutrons to produce a neutron capture reaction and subsequent decay that emits alpha and lithium particles.

The rationale and requirements for the development of boron neutron capture therapy of brain tumors.

The dismal clinical results in the treatment of glioblastoma multiforme despite aggressive surgery, conventional radiotherapy, and chemotherapy, either alone or in combination has led to the development of alternative therapeutic modalities. Among these is boron neutron capture therapy (BNCT). This binary system is based upon two key requirements: (1) the development and use of neutron beams from nuclear reactors or other sources with the capability for delivering high fluxes of thermal neutrons at depths sufficient to reach all tumor foci, and (2) the development and synthesis of boron compounds that can penetrate the normal bloodbrain barrier, selectively target neoplastic cells, and persist therein for suitable periods of time prior to irradiation.

Intensified regimen for advanced head and neck squamous cell carcinomas.

Objective: To devise an intensified treatment regimen for patients with advanced, resectable head and neck squamous cell carcinomas.

Design: Phase I/II clinical trial consisting of perioperative cisplatin chemoradiotherapy, surgical resection, intraoperative radiotherapy, and postoperative cisplatin chemoradiotherapy.

Setting: The Ohio State University Comprehensive Cancer Center, Columbus.

Determination of the efficacy of topical oral pilocarpine for postirradiation xerostomia in patients with head and neck carcinoma.

Pilocarpine hydrochloride suspended in a candy-like pastille was evaluated as a topical treatment for radiation-induced xerostomia in head and neck cancer patients. This local delivery system, which differs from systemically administered pilocarpine preparations, was developed to hopefully maximize the local response and minimize the systemic side effects. A prospective, randomized, double-blind, placebo-controlled trial was undertaken to determine objective and subjective efficacy in reversing the decrease in salivation.