Safety_Series_025_1968 - gnssn - International Atomic Energy ...

This publication is no longer validPlease see http://www.ns-iaea.org/standards/2. 2. 2. F orm s o f m edical exp osu reA ccord in g to th eir ch a ra cte ristics, the foregoing sou rces maybeused in m e d ica l ra d iolog y fo r eith e r d ia gn ostic o r th erapeu ticp u rp oses.2. 2. 2. 1. D iagn ostic u sesF or diagnostic pu rp oses X -r a y or radionuclide s o u rce s can beused.X -r a y s a re by fa r the m ost w idely u sed. The apparatus e m ­p loyed fo r the p u rp ose is the con ven tion al type o f g e n e ra to r withvoltage betw een 50 and 100 kV.The use of radionuclides for diagnostic purposes is in the mainlim ited to unsealed s o u rce s , w hose d istribu tion in the body can beu sed fo r a n a to m ica l (sca n n in g) o r fu n ction a l (tu rn o v e r) stu d ie s.2. 2. 2. 2. T h e ra p e u tic u sesThe foregoin g sou rces have a great variety o f therapeutic u seswhich can be divided into teletherapy (or rem ote radiotherapy), su p erficial therapy and in terstitial therapy.The m ain s o u rce s u sed in teleth erapy a re h ig h -en erg y X -r a yapparatus (in the 200-kV range — Van de G raaff m a ch in es, lin ea ra c c e le r a to r s and betatron s), ele ctro n radiation g en era tors (lin eara c c e le r a t o r s and b eta tron s) and g a m m a -ra y g e n e ra to rs (radium ,cob a lt o r ca e siu m units).F or s u p e rficia l radioth erapy the follow in g types o f apparatuscan be u sed : v e r y -lo w -e n e r g y X -r a y apparatu s; seale d gam m as o u r c e s (radiu m -226 and c o b a lt-6 0 a p p lica to rs); and sea led betaso u rce s (phosphorus-3 2 and stro n tiu m -9 0 /y ttriu m -9 0 a p p lica tors).In terstitia l radioth era p y can u s e : seale d gam m a s o u r c e s(radiu m -226, co b a lt-6 0 o r g o ld - 198); and u n s e a le d 's o u rce s (gold-198, p h osp h oru s-32 o r iod in e-131).2. 2. 3. Results o f medical exposureIn con sid erin g the resu lts o f m e d ica l e x p osu re, a d istin ctionshould be m ade betw een the irra d ia tion o f sta ff engaged in r a d io ­lo g ica l exam inations and treatm ent, and the irradiation of patients.A s the irradiation o f staff is dealt with in the next section , only i r ­57