TG 303 MRI in HDR brachy

Question 1

what does report include?

Answer 1

-gyne and prostae cancer
-rational for MR in brachy
-review of applicators, clinical trials
-MR protocols
-guidelines for commissioning, clinical implementation, and QA
-risk based analysis

Question 2

pros of MRI

Answer 2

-superior soft tissues contast
-improves OAR dosimetry and target escalation
-non-ionizing and doesn’t require radiocontrast agents

Question 3

closed or open bores?

Answer 3

usually closed because SNR is not good enough with low field strenght open bore MRI

Question 4

TG reports addressing use of MRI

Answer 4

MRI subcommittee TG 1, 118, 132

Question 5

optimal worklfow

Answer 5

optimal is MR only
-needles inserted outside bore, physician reaches into bore to adjust needles

Question 6

gradient non-linearity artifacts

Answer 6

expected to be small bnecause implant is very close to magnet bore center

Question 7

material for applicators

Answer 7

titanium or plastic

Question 8

metallic objects in MR brachy room

Answer 8

can touch patient and cause burns!

Question 9

highst risk failure

Answer 9

target contouring

-other high risk failures are badly contoured needles, calcifications mistaken for needles

Question 10

MRI-guided BT

Answer 10

the applicator and/or needles are implantedusing real-time MRI guidance

Question 11

specific QA considerations for MRI integrated into HDR

Answer 11

Initial:
-verify MR safety of equipment
-optimize pulses
-train staff
-make MRI safety questionnaire
-commission applicator models and image registration software
-E2E

each day:
-image quality QA
-pre-implant check
-MR safety- form and screen person, prevent skin-skin contact; if non-magnetic metal is used, make sure it doesn’t burn patuent

monthly: MRI imaging QA