Tesis doctoral de Mercé Beltrán Vilagrasa
T h is th esis ex am ines th e dose im p lications related to anatom ical ch anges ex p erienced b y p atients w ith h ead and neck cancer (h nc ) during radiation th erap y (rt ). T h e study is carried out for b oth conv entional 3 d conform al (3 d c rt ) and intensity m odulated (im rt ) tech niq ues. W e h av e analyzed a large num b er of organs at risk , som e of w h ich h av e not b een p rev iously studied. A dditionally, dose v ariab les sh ow ing im p ortant v ariations w ere indiv idually inv estigated for th e group of p atients treated w ith im rt . F inally, w e assessed w h eth er treatm ent rep lanning is a good tool to restore th e initial p lanning dose ch aracteristics. T h e study included 2 8 p atients diagnosed w ith locally adv anced h ead and neck sq uam ous cell carcinom a, 1 2 of w h om w ere treated w ith 3 d c rt and 1 6 w ith im rt . T h e treatm ent area included th e p rim ary tum or in addition to th e cerv ical and sup raclav icular b ilateral nodes. T h e m eth odology w as designed to acq uire new c t im ages of th e p atient in sessions num b er fifteen and tw enty-fiv e, ap p rox im ately corresp onding to th e th ird and fifth w eek of treatm ent. T h e contours of th e treatm ent v olum es and th e organs at risk defined in th e initial p lanning c t w ere m anually adjusted on th ese new c t im ages, follow ed b y a dose distrib ution calculation corresp onding to initial p lan w ith w h ich th e p atient is b eing treated. W e analyzed data from th e dose-v olum e h istogram s corresp onding to dosim etry studies in each c t . W eigh t w as recorded w eek ly for all p atients. In th e second p art of th e th esis, an indiv idual study of p atients treated w ith im rt w as m ade. D ose distrib utions calculated on c t ¿s tak en during treatm ent w ere analyzed w h en th e initial dose restrictions w ere ex ceeded or if v ariations less th an -5 % or ab ov e + 1 0 % w ith resp ect to th e initial calculated v alues ex isted. W h en v ariab ility lim its w ere ex ceeded, th e corresp onding c t dosim etry w as adap ted b y op tim izing field irradiation fluencies from initial treatm ent p lan. B oth group s of p atients p resented sim ilar anatom ical ch anges, including w eigh t loss and reduction in v olum e of th e follow ing structures, nam ely th e treatm ent area, th e treatm ent v olum es and th e p arotids. T h e w eigh t and v olum e w ith in th e treatm ent area v ariab les sh ow ed correlation. Im p lying th at w eigh t can also act as a p rognostic factor to identify w h ich p atients m ay ex p erience im p ortant ch anges in th e treatm ent area. It h as b een sh ow n th at dose v ariations com p rom ise th e v alidity of th e initial dose distrib ution to a greater ex tent in th e im rt group . T h is arises p rim arily b ecause th e treatm ent v olum es ex h ib ited cov erage loss only in th e im rt group and additionally, b ecause discrete m easured dose increm ents to th e organs at risk jeop ardize th e b enefits th at th e im rt tech niq ue p rov ides. T h e indiv idualized study of th e im rt group sh ow s th at th e m ain factors indicating a need for initial p lanning m odification: loss of dose cov erage for th e treatm ent v olum e, dose increases to th e p arotid glands and finally th e ab sorb ed dose increase to oth er organs at risk such as lip s, th e oral cav ity and m iddle neck structures. L oss of dose cov erage in treatm ent v olum es togeth er w ith dose increases to th e o a r are detected m ainly in t c 2 . A cq uiring a t c at 1 5 th fraction w ill th erefore identify m ost cases th at could b enefit from adap tiv e rt . F inally, w e h av e sh ow n th at rep lanning b ased on th e op tim ization of initial field fluencies allow us to adap t th e dose distrib ution to anatom ical ch anges and th us ach iev e th e sam e dose constraints reach ed in th e initial p lan.
Datos académicos de la tesis doctoral «Impacte dels canvis anatómics sobre la distribució de dosi en els pacients amb cÁ ncer de cap i coll tractats amb 3dcrt i imrt«
- Título de la tesis: Impacte dels canvis anatómics sobre la distribució de dosi en els pacients amb cÁ ncer de cap i coll tractats amb 3dcrt i imrt
- Autor: Mercé Beltrán Vilagrasa
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 14/12/2012
Dirección y tribunal
- Director de la tesis
- Mercé Ginjaume Egido
- Tribunal
- Presidente del tribunal: albert Biete solí
- montserrat Ribas morales (vocal)
- (vocal)
- (vocal)