Radiotherapy Treatment of Early-Stage Prostate Cancer with IMRT and Protons: A Treatment Planning Comparison

Abstract

Purpose-To compare intensity-modulated photon radiotherapy (IMRT) with 3D-conformal proton therapy (3D-CPT) for early stage prostate cancer, and explore the potential utility of intensitymodulated proton therapy (IMPT).Methods-Ten patients were planned with both 3D-CPT (2 parallel-opposed lateral fields) and IMRT (7 equally spaced coplanar fields). Prescribed dose was 79.2 Gy (or cobalt Gray-equivalent, CGE for protons) to the prostate gland. Dose-volume histograms, dose conformity, and equivalent uniform dose (EUD) were compared. Additionally, plans were optimized for 3D-CPT with nonstandard beam configuration, and for IMPT assuming delivery with beam scanning.Results-At least 98% of the PTV received the prescription dose. IMRT plans yielded better dose conformity to the target, while proton plans achieved higher dose homogeneity, and better sparing of rectum and bladder in the range below 30 Gy/CGE. Bladder volumes receiving over 70 Gy/CGE (V 70 ) were reduced, on average, by 34% with IMRT vs. 3D-CPT, while rectal V 70 were equivalent. EUD from 3D-CPT and IMRT plans were indistinguishable within uncertainties, for both bladder and rectum. With the use of small-angle lateral-oblique fields in 3D-CPT and IMPT, the rectal V 70 was reduced by up to 35% compared to the standard lateral configuration, while the bladder V 70 increased by less than 10%.Conclusions-In the range over 60 Gy/CGE, IMRT achieved significantly better sparing of the bladder, while rectal sparing was similar with 3D-CPT and IMRT. Dose to healthy tissues in the range below 50% of the target prescription was substantially lower with proton therapy.

Female Pelvis: Genital Organs

“…There are no randomised trials comparing IMRT with PBRT. Two planning studies comparing conformal proton therapy with IMRT have reported confl icting results; one study suggested that whilst IMRT is superior in terms of bladder sparing, there is no difference in terms of rectal dose sparing (Trofi mov et al 2007 ); the other suggested that PBRT is better at reducing dose to normal structures (Vargas et al 2008 ). …”

Role of proton therapy in the treatment of cancer

“…Fakat bugünkü çalışmalar bu olasılığı çok desteklememektedir. [56] Prostat kanserinde kanser spesifik sağkalımın uzun olması nedeniyle proton, foton karşılaştırmalı randomize çalışma yapmak zor olmaktadır. Sağka-lım ve toksisite açısından özellikle IMRT ve proton karşılaştırmalı çalışmalar yürütülmektedir.…”

Technological Advances in Radiation Therapy for Prostate Cancer

“…Although the unique dose distribution of protons suggests a potential dosimetric advantage, studies comparing 3D conformal proton beam therapy and photon IMRT have shown mixed results [62][63][64]. Whether these differences between proton beam radiation and IMRT plans actually translate into clinically relevant results remains unknown.…”