- Slides: 45
Modern Radiation Oncology Jamie Cesaretti, M. D. , M. S. Radiation Oncology Terk Oncology, Jacksonville, FL
The Number and Type of Ionizing Radiation Induced Lesions in DNA – per Gray/per Cell! TYPE OF LESION double strand break NUMBER /Gy /diploid cell 40 single strand break 500 -1000 base damage 1000 -2000 sugar damage 800 -1600 DNA-DNA crosslinks DNA-protein crosslinks 30 150
CURE RATE = DOSE There is a significant difference between less than 70. 2 Gy (2. 5 D) and the higher doses. At elevated doses there is still a significant “persistant cancer at biopsy” (risk versus benefit) 14% 81 Gy 20% 75. 6 Gy 22% 70. 2 Gy 58% <70. 2 Gy ASTRO 2004
Cure Rate = Radiation Dose
Cancers grow beyond their original organ in predictable ways. BJ Davis, et al. Cancer 1999; 85: 2630 -7.
An Interesting Trial of Margins around the Prostate and Radiation Dose
MRC Dose Escalation Study Dose Margin
MRC Dose Escalation Study BJ Davis, et al. Cancer 1999; 85: 2630 -7.
Toxicity = Technique IMRT
IMRT with DMLC (sliding gap) l. Each pair of leaves forms an individual gap l. Gaps change in width as a function of beam-on time (MU) • • • a l. Final n z a. . +. . n. . +. . z intensity is sum of the individual sliding gaps
IMRT versus VMAT
Toxicity = Technique IGRT
Toxicity = Technique
Toxicity = Technique
Toxicity = Technique MV X-rays k. V Cone Beam CT Image at proton centers Helical MV CT k. V X-rays MV Cone Beam CT
The probabilities for prostate staying within <2 mm to its initial position are: 94. 8% supine WRB 91. 5% supine WORB 92. 3% prone WRB 79. 2% prone WORB.
Target Delineation MRI Treatment Planning
T 2 axial image with surface coil , Left SV dark on T 2 (and dark on T 1…
Optimal Target Identification Fused CT/MRI showing Seminal Vesicle invasion on MRI: This justifies including gross seminal vesicle disease to 75. 6 Gy PTV Fused CT image Fused MRI image
WITHOUT RECTAL BALLOON WITH RECTAL BALLOON
Results (A) With Balloon (B) Without Balloon Sample screen shot showing isodose lines around prostate with (A) and without (B) rectal balloon in place
Are all radiation particles created equal?
The lay implication of the marketing material is that photon radiation puts radiation around the pelvis and rectum “carelessly” and that a higher level of precision is more appropriate.
Many prostate cancers have Subclinical spread to peri-rectal and pelvic lymph nodes at the time of initial treatment.
We are seeing “new” failure patterns in the local proton patients. Photon radiation salvage plan
Another photon radiation salvage plan
From: Intensity-Modulated Radiation Therapy, Proton Therapy, or Conformal Radiation Therapy and Morbidity and Disease Control in Localized Prostate Cancer JAMA. 2012; 307(15): 1611 -1620. doi: 10. 1001/jama. 2012. 460 Date of download: 6/1/2016 Copyright © 2016 American Medical Association. All rights reserved.
Comparison of Treatments
ASCO Prostate Cancer update March 2017