ABR TMP study guide
ABR TMP · Work through your exam, one topic at a time.
The ABR Therapeutic Medical Physics (TMP) Part 2 Qualifying Exam is the middle step of the three-part ABR medical physics certification sequence. It is intended for physicists who have already passed both sections of Part 1 and who are completing, or are on track to complete, a CAMPEP-accredited residency or DMP program by August 31 of the exam year. The ABR TMP study guide has 5 sections and about 1,772 words.
01Treatment planning and dosimetry
Photon beams are calibrated with the TG-51 protocol at 10 cm depth, 10 × 10 cm² field, 100 cm SSD, and the result is reported as cGy/MU at dmax. Percentage depth dose (PDD) depends on SSD, field size, and energy; tissue-maximum ratio (TMR) is independent of SSD, which is why isocentric calculations use TMR while fixed-SSD calculations use PDD.
325 words, about 2 min02Treatment delivery
Delivery accuracy begins with a correct monitor-unit calculation: MU = prescribed dose ÷ (output × Sc × Sp × depth factor × inverse-square × accessory factors). Every factor propagates linearly, so one mis-entered value shifts the whole treatment.
310 words, about 2 min03Machine calibration and quality assurance
TG-51 uses an ion chamber with a cobalt-60 calibration coefficient N D,w, measured at 10 cm depth, 10 × 10 cm², 100 cm SSD in water, corrected for temperature-pressure (P tp), ion recombination (P ion, important for pulsed and scanned beams), polarity (P pol), and electrometer (P elec), plus the beam-quality factor k Q interpolated from the measured quality specifier. TG-21, which referenced dmax in a phantom and used exposure calibration factors, is a classic distractor.
277 words, about 1 min04Brachytherapy
The dose rate is D(r,θ) = S k · Λ · [G(r,θ)/G(r0,θ0)] · g(r) · F(r,θ). Air kerma strength S k is expressed in U, where 1 U = 1 cGy·cm²/h = 1 µGy·m²/h; Λ is the dose-rate constant in cGy/h/U at the reference point; g(r) is the radial dose function (attenuation and scatter); F(r,θ) is the anisotropy function.
285 words, about 1 min05Imaging for radiation therapy and simulation
CT simulation fixes the treatment geometry: indexed couch, immobilization, isocenter marking, and a protocol with appropriate field of view and slice thickness (≤3 mm for most sites, 1 mm for intracranial radiosurgery). Hounsfield units must be converted to electron density with a calibration phantom, and that curve is scanner- and kVp-specific.
575 words, about 3 min