Стереотаксической радиохирургии для гинекологического рака
Summary
Стереотаксическая тело лучевой терапии (SBRT) включает в себя изображение наведением, абляционного излучение доставляется к раку цели поддаются химиотерапии или обычной лучевой терапии. Роботов вооруженных Cyberknife SBRT системы, с использованием сложных локализации цели, обеспечивает hypofractionated доз радиации способны стерилизации рака цели. В этой статье мы рассмотрим новую терапевтическую роль SBRT для гинекологического рака.
Abstract
Stereotactic body radiotherapy (SBRT) distinguishes itself by necessitating more rigid patient immobilization, accounting for respiratory motion, intricate treatment planning, on-board imaging, and reduced number of ablative radiation doses to cancer targets usually refractory to chemotherapy and conventional radiation. Steep SBRT radiation dose drop-off permits narrow ‘pencil beam’ treatment fields to be used for ablative radiation treatment condensed into 1 to 3 treatments.
Treating physicians must appreciate that SBRT comes at a bigger danger of normal tissue injury and chance of geographic tumor miss. Both must be tackled by immobilization of cancer targets and by high-precision treatment delivery. Cancer target immobilization has been achieved through use of indexed customized Styrofoam casts, evacuated bean bags, or body-fix molds with patient-independent abdominal compression.1-3 Intrafraction motion of cancer targets due to breathing now can be reduced by patient-responsive breath hold techniques,4 patient mouthpiece active breathing coordination,5 respiration-correlated computed tomography,6 or image-guided tracking of fiducials implanted within and around a moving tumor.7-9 The Cyberknife system (Accuray [Sunnyvale, CA]) utilizes a radiation linear accelerator mounted on a industrial robotic arm that accurately follows patient respiratory motion by a camera-tracked set of light-emitting diodes (LED) impregnated on a vest fitted to a patient.10 Substantial reductions in radiation therapy margins can be achieved by motion tracking, ultimately rendering a smaller planning target volumes that are irradiated with submillimeter accuracy.11-13
Cancer targets treated by SBRT are irradiated by converging, tightly collimated beams. Resultant radiation dose to cancer target volume histograms have a more pronounced radiation “shoulder” indicating high percentage target coverage and a small high-dose radiation “tail.” Thus, increased target conformality comes at the expense of decreased dose uniformity in the SBRT cancer target. This may have implications for both subsequent tumor control in the SBRT target and normal tissue tolerance of organs at-risk. Due to the sharp dose falloff in SBRT, the possibility of occult disease escaping ablative radiation dose occurs when cancer targets are not fully recognized and inadequate SBRT dose margins are applied. Clinical target volume (CTV) expansion by 0.5 cm, resulting in a larger planning target volume (PTV), is associated with increased target control without undue normal tissue injury.7,8 Further reduction in the probability of geographic miss may be achieved by incorporation of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET).8 Use of 18F-FDG PET/CT in SBRT treatment planning is only the beginning of attempts to discover new imaging target molecular signatures for gynecologic cancers.
Protocol
Discussion
Поощрение ранних результатов SBRT вызвали клиническое исследование радиохирургии для лечения персистирующей или рецидивирующей гинекологических видов рака. 7, 8, 15 Данные вопрос радиобиологических эффектов и режим гибель клеток в результате SBRT. Малые клинические исследования показали, что дозы облучения абляционного предоставляемые SBRT производить целевые болезней темпами, превышающими 90%. В отличие от обычного излучения, было сложно совмещать с SBRT радиосенсибилизирующее и цитотоксических / цитостатической химиотерапии. Лучше рак таргетинга за счет увеличения планирования расширения объема лечения и через включение 18 F-ФДГ ПЭТ / КТ изображений улучшил клинические исходы. В то время как важно изучить другие способы доставки эскалации дозы излучения с высокой точностью, она остается нерешенным ли SBRT может предоставить эквивалент терапевтической эффективности, как низкие и высокие дозы брахитерапии. Действительно, брахитерапия является более распространенным и валиот техники для достижения эскалации дозы облучения в мишенях гинекологического рака. Таким образом, как энтузиазм и благоразумие, необходимые в чтении имеющихся данных SBRT для лечения рака гинекологических.
Disclosures
The authors have nothing to disclose.
Acknowledgements
Это исследование было поддержано Дело Всесторонний Онкологический центр (P30 CA43703).
Materials
| Name of the device | Company | Catalogue number | Comments |
| Cyberknife system | Accuray (Sunnyvale, CA) |
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