COMPARISON OF DOSE DISTRIBUTIONS IN PATIENTS TREATED WITH X-RAY BEAMS OF WIDELY DIFFERENT ENERGIES
COMPARISON OF DOSE DISTRIBUTIONS IN PATIENTS TREATED WITH X-RAY BEAMS OF WIDELY DIFFERENT ENERGIES
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DOI：
10.1148/58.3.361
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发表时间：
1952-01-01
期刊：
影响因子：
19.7
通讯作者：
HARVEY, RA
中科院分区：
文献类型：
--
作者：
GARRISON, H;ANDERSON, J;HARVEY, RA
迄今为止发表的所有关于超高压X线治疗的研究都表明，在辐射波长方面缺乏特异性的抗癌优势。超电压治疗的主要优点是增加了传递到深层肿瘤的辐射量。正常的组织在接受高能辐射的耐受性方面表现出一些相当微小的任意差异。这些差异很可能与在20万伏、40万伏和1，000，000伏下产生的吸收性质的物理剂量测量的困难有关，23，000，000伏电子感应加速器使我们有机会在比迄今为止所能得到的电压范围大得多的电压范围内评估剂量效应的差异。本报告的目的是比较40万伏X射线机和2300万伏电子感应加速器的X射线剂量分布，这两种射线源的辐射吸收至少有五个不同之处，在开始时应该强调。这些措施如下：1.最大剂量为400毫克。半值层为2.75 mm的X射线。Cu大约位于表面，而对于电子感应加速器，它略高于4 cm。2. 400-μ l的相对剂量。x光10厘米处为37%。20厘米处为10%;而电子感应加速器则在10厘米处达到81%。20厘米处占54%，两个都是10厘米。端口（1，4）。3.侧向散射对于400 kv. p. X射线很重要，但对于电子感应加速器X射线，散射主要是向前的（1，4）。4.进入皮肤剂量在400 kv时达到峰值。X射线和电子感应加速器的峰值剂量的大约35%。对于400-μ m，出口皮肤剂量通常可以忽略不计。X射线，而用电子感应加速器，它可能高于入射皮肤剂量（1）. 5.在较低电压下，辐射的相对吸收在骨中高，在脂肪中低;它更接近于电子感应加速器（3，6）为了实用，我们选择了5名接受电子感应加速器治疗的病人，并将他们的实际剂量分布与使用较低的电子感应加速器可能导致的剂量分布进行了比较。这些患者的肿瘤位于身体的不同部位，并且位于中心和偏心位置。治疗计划以常规方式进行，没有考虑或参考竞争方法，除了一例胸部病例用于演示。这两种技术的治疗野数不同，仅仅是因为23兆电子伏的x射线具有更大的范围，几乎可以无限地接近病变。两种方法之间的治疗次数、每日治疗量、给药速率和总体治疗期（周）无显著差异。
All of the workpublished to date on supervoltage roentgen therapy indicates a lack of specific cancericidal advantage in relation to wave length of the radiation. The chief advantage of super-voltage therapy is an increase in quantity of radiation delivered to a deeply situated tumor. Normal tissues unavoidably irradiated have shown some rather slight arbitrary differences in tolerance to higher-energy radiations. These differences may well be related to difficulties in physical dosage measurements of absorption of qualities so closely related as those produced at 200,000 volts, 400,000 volts, and 1,000,000 volts.The 23,000,000-volt betatron has given us an opportunity to evaluate differences in dosage effects over a much greater range of voltage than hitherto available. The purpose of this presentation is to compare the dosage distribution of x-rays from a 400,000-volt x-ray machine with those from a 23,000,000-volt betatron.There are a minimum of five differences in the absorption of the radiations from these two sources which should be emphasized at the start. These are as follows:1.The maximum dose for 400-kv. x-rays with a half-value layer of 2.75 mm. Cu is approximately at the surface, while with the betatron it is slightly over 4 cm. within the body (1, 4).2.The relative dose for 400-kv. x-rays is 37 per cent at 10 cm. and 10 per cent at 20 cm.; with the betatron it is 81 per cent at 10 cm. and 54 per cent at 20 cm., both with 10-cm. ports (1,4).3.Side scatter is important for 400-kv.p. x-rays, but for the betatron x-rays scatter is predominantly forward (1,4).4.The entrance skin dose is at the peak with 400-kv. x-rays and at approximately 35 per cent of the peak dose with the betatron. The exit skin dose is usually negligible with 400-kv. x-rays, while with the betatron it may be higher than the entrance skin dose (1).5.Relative absorption of the radiations is high in bone and low in fat at lower voltages; it is more nearly equal with the betatron (3, 6).For practical purposes we have selected 5 patients treated with the betatron and have compared their actual dose distributions with those which might have resulted from the use of the lower-energy machine.These patients had tumors located in different parts of the body and in both central and eccentric position. Treatment planning was conducted in a routine fashion and without thought or reference to competing methods, with the exception of one chest case for purposes of demonstration. The number of fields of treatment differ with the two technics, simply because the 23-mev x-rays have so much greater range that one has an almost unlimited number of approaches to a lesion. The number of treatments, size of daily treatments, rate of dosage administration, and over-all treatment period in terms of weeks are not significantly different between the two methods.