PIONS SPARK CANCER THERAPY - Report to Senior Electronics Engineers & Managers - March 1975 Volume 95 Number 3

Sep 29, 2026

Explains how nuclear particles and radiation can be used for cancer radiotherapy, highlighting challenges in precisely regulating X-ray and electron-beam damage to surrounding healthy tissue. Describes development of a medical pion generator by Stanford scientists, intended to improve control of treatment for difficult cancers. Details pion behavior in tissue, expected effectiveness versus conventional radiation, and an instrument design using superconducting magnetic coils and directed beams. Mentions development timeline and projected hospital installation plans.

LanguageEnglish

CategoryHealthcare

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Pages9

Reading Time23 min

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PIONS SPARK CANCER THERAPY

Rationale for pion-based radiotherapy

Stanford pion generator development

Clinical advantages and expected effectiveness

Report to Senior Electronics Engineers &Managers March 1975Volume 95,Number 3 PIONS SPARK CANCER THERAPY Nuclear particles and radiation,when energized,can damageor destroy living tissue—as nuclear weapons so graphically11lustrate.But this potential to harm has been put to auseful purpose in medical radiotherapy,where cancerouscells can be destroyed by powerful x-ray or electron beams. Unfortunately,these forms of radiation also can destroyhealthy tissue,as they are difficult to regulate accuratelyand tend to "pass through"the tumor or cancerous regionand may damage adjacent healthy cells or organs.Nevertheless,many malignancies now are treated and cured in this manner,and megavolt linear accelerators can be found in cancercenters and hospitals around the wor1d. Now,thanks again to the synergism of high-energy physicsand medical technology,a new particle generator—the piongenerator—promises to be as significant in future cancerradiotherapy as x-rays and electron beams have been forthe past two decades. The medical pion generator has been under development forthe past five years.According to the Stanford Universityscientists,it should allow physicians to treat cancersthat are stil1 difficult to contro1 with conventionalmethods:cancers around the throat and neck,certain brainand lung tumors,and those high1y-resistant to radiation,such as cancer of the pancreas.It has been estimated that 90,000 annual cases in the U.S.alone fit into thesepresent1y-untreated categories. The pion,or pi-meson,which may provide a distinctivebreakthrough in these cases,is the subatomic particlethat serves to "bind"protons and neutrons in the nuclei.Although short-lived,the pion can be controlled veryaccurately,allowing treatment with little or no damageto nearby organs and tissue. Copyright®1975 by Industrial Research,222 S.RiversidePlaza,Chicago,I11.60606.Reproduction without permissionis prohibited. According to the Stanford scientists—Drs.Malco¹m Bagshaw,Henry Kaplan,H.Alan Schwettman,Douglas Boyd,and WilliamFairbank—when pions strike living tissue,they slow downand eventually are captured by nuclei in atoms of livingcells.A nucleas that captures a pion literally explodesfrom the excess energy,producing a miniature nuclear blastcalled a "star formation." Given off in this explosion are proton and neutron fragments,x-rays,gamma rays,and other particles.These destroysurrounding cells as wel1."Because the nuclear fragmentsproduced in this explosion cause such great destruction,"Dr.Bagshaw says,"pion therapy is expected to be aboutthree times as effective in killing tumor cells as x-rayshaving comparable radiation dosage." But with this extraordinary destructive force,pions can bestopped quite precisely in the target region by varying theirmomentum.Thus tissue damage can be confined almost entirelyto the tumor.A further advantage is that the gamma radiationemitted during the cells'"star formation"can be detected,allowing doctors to see exact1y where ce11 destruction isoccuring.(X-rays do not signal their activity,and sctherapists cannot know as precisely where the beam ishaving effect.) Dr.Schwettman told Blectro-Technology that the pion generator is a large tank about 5-m(17-ft)long,consistingof 60 superconducting magnetic coils at either end.Oneend is connected to Stanford's Mark III linear accelerator,which produceε pions as 500-MeV electron 3 strike titaniumtargets.These pions escape the target in al1 directions,and are collected 5y rnagnets and channeled into 60 beams.At the other end of the tank,a second set of superconductingmagnets takes the 60 beams and aims them at the patient.Slitsalong the tark's circuference,nidway between the ends,areadjusted to alter the intensity of the pion beam strikingthe patient's tumor. Although three other facilities here and abroad are investigatingthe medical advantages of pions,the Stanford group is theonly one thus far working specifically on an instrument foractual use in hospita

FAQs

为什么传统的X射线或电子束疗法会对健康组织造成影响？

因为这些辐射难以被精确调节，容易穿过肿瘤区域并可能损伤相邻的健康细胞或器官。

pion therapy预期比同剂量的X射线更有效的原因是什么？

捕获pion后会释放引发“star formation”的核爆式能量，产生会破坏周围细胞的核碎片等效应，因此预期对杀死肿瘤细胞的效果可达约三倍。

Stanford的pion generator在结构和束流控制上如何工作？

设备为约5米长的装置，两端各有60个超导磁线圈：一端由线性加速器产生并收集pion，再由另一端磁场将分配的60束引导至患者；通过中部沿圆周布置的狭缝调节束流强度以定位肿瘤区域。

Sep 29, 2026

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