Organ risk assessment by TLO to improve treatment planning of cancer patients in Bangladesh

Abstract

Radiotherapy is the most commOn modality for treating human cancers, About 60,80% of cancer patients need radiotherapy at some lime or othcr, clther for curative or pallialive purposes, This is the only application of radialion. which intentionally delivcrs very high dos.s to humans, Til. oulcomc of mdiotherapy in cancer care is heavily dependent on the quality or lhe treaul1enl. Radialion dose to organs outside lhe lrealment field can be si!>l1ifieantand there rare i, or clll,;cal interesl. To achieve optimum resul!, " judicious balance bem'een the lolal dose of radiotherapy delivered and tile tbreshold limil or the ;urroundLng normal critical tissues IS requircd. Beller lrealmenl eonlrol with higher dose to tumor volume and at lhe samc time proteeling the normal tissue against radiation injury can bc achieved by proper treatment planning. In lhe pre,ent work dose dislribulion to the normal tis;ue, or organ, out, ide the trealment volume due to scattering radi"tion during radiotherapy procedure was measured by LiF TLD.100 technique, Three ""Co teletherapy unib were used in this work, The relative risk factor to normal ti"ue or organ i, obtained by applying: JCRP-60 (1990) recommendalion. The measurement is conducled in four steps; (I) Dosimetry of 6OCO telelhcrapy units rollowing lAEA do,imctry prolocol TRS-277 with lbe establishment of the empirical formula Dm", ~ a, + a1 - a,r', (2) scattering radiation dose contribution to different part, of paticnt's body during radiotherapy Ircatmcnt for various canecr site is measured and cmptrical formula (s) arc c,lablishcd fnr scmlcring radiation dose contribution 10 lhe nearest organs dUl'ing cervical treatment, (3) a correction factor to convert skLn to orl;an depth dose due to scaltering radialion is established. and (4) organ rbk factor outside the treatmcnl volume due 10 scattering radiation Is obtained by calculating org"n CqULvalent do,e, Thc result Oblained would be useful to recommend measure, for the protection of patient's normal organ by applying proper lreatment planning during radiotherapy treatmenl, which is a prerequisite for quality assurance in radiotherapy.