质子和其他放射治疗肿瘤的比较

质子加速器是目前世界上最先进的放射治疗设备。本文对质子和目前各国常用的常规射线(兆伏特级的光子和电子)，在肿瘤的放射治疗方面进行了比较。并复习了世界各国用质子治疗肿瘤的经验，介绍质子治疗肿瘤的优点、发展历史以及发展前景。质子束进入人体组织时，其大量的能量集中在接近射程终点，称为Bragg峰。放射治疗医生可以通过调节质子加速器能量的方式，使高能量区集中在病人体内一定的区域；在此高量区的后方，放射剂量骤降为零。因此，医生可以使放射线的高剂量区集中在靶区(肿瘤区)，避免周围正常组织部受到照射。而用常规射线照射时，周围正常组织仍受到较高量的照射。用目前先进的三维适形放射治疗和调强放射治疗技术，只需用少数的照射野，即可达到非常满意的放射剂量分布。到2004年2月，世界上已有11个国家正在开展质子治疗工作；已用质子治疗病人35838例。所治疗的肿瘤有眼葡萄膜黑色素瘤、中枢神经系统肿瘤、颅底肿瘤、前列腺癌、非小细胞肺癌、胃肠道肿瘤、鼻咽癌、乳腺癌和官颈癌等，均取得较好的效果。目前已引起世界各国放射治疗学界的重视。

Comparison of proton with conventional radiotherapy in cancer treatment

Proton accelerator is the most advanced radiotherapy equipment. This paper is to review the clinical experiences abroad, to introduce the benefit, developing history and the future in the treatment of cancer with proton. Proton beam deposits most of its energy at the end of its travel, called Bragg peak. By adjusting the energy of the accelerator, the oncologist can adjust the depth within the patient wherein that energy is deposited. Once a proton releases its energy, at a point called the Bragg peak, it stops. It does not continue through the patient; tissues beyond the tumor are not reached. Thus, the physician can deliver a sufficiently high dose to a target volume (the tumor) while still sparing normal tissues to a much greater extent than its possible with conventional irradiation. Using advanced 3D CRT and IMRT technique, less radiation fields are needed to offer an excellent radiation dose distribution to the target volume. Up to February 2004, 35838 patients, including those with choroid melanoma, cancers of central nervous system, base of skull, prostate gland, non-small call carcinoma of the lung, gastro-interest cancer, nasopharyngeal carcinoma, breast cancer and carcinoma of the cervix have been treated with proton in eleven countries abroad with excellent treatment results.