How does TI (Therapeutic Index) relate to drug safety?
Larger the TI, the safer the drug
Smaller the TI, less safe the drug; must be more careful have to be with dosing
What advantages do alpha-emitters have over beta-emitters as radiopharmaceuticals?
Alpha emitters: short path length, can target individual cancer cells
Beta emitters: wider path length, less specificity, more tox
What critical needs do alpha-emitters address in cancer therapy?
Potential to eradicate disseminated tumor cells or sub-population of tumor stem cells.
This requires:
- A systemic targeted therapy
- Minimally susceptible to chemo- or radio-resistance
- Potent enough to sterilize individual cells and microscopic tumor clusters
- Acceptable tox profile
What radiation qualities are needed for accurate dosimetry calculations?
Activity distribution as a function of time (at cellular and subcellular level)
How is activity distribution measured in vitro?
- Uptake on the cell surface (or within the cell)
2. Known fraction in the surrounding solution
How is activity distribution determined clinically?
- Modeling 3D geometry of spheroid (or tissue geometry determined by microscopic tissue biopsy samples)
- Mathematic modeling of carrier molecules diffusing through tissue and binding to cell surface
When do you use Gray (Gy) over Sievert (Sv) in radiation studies?
Deterministic effects are conventionally compared to values of absorbed dose expressed by the SI unit gray (Gy)
Sievert (Sv) implies that only stochastic effects are being considered
Units used to measure specific activity
Becquerel (Bq)
Curie (Ci)
Rutherford (Rd)
Units used to measure absorbed dose
Gray (Gy)
Erg per gram (Erg/g)
Rad
