Dissertation defence (Physics): FM Jarkko Niemelä
FM Jarkko Niemelä defends the dissertation in Physics titled “NOVEL DOSIMETRY METHODS FOR SMALL PHOTON FIELDS IN EXTERNAL BEAM RADIATION THERAPY” at the University of Turku on 9 May 2025 at 12.00 (University of Turku, Quantum, Auditorium, Vesilinnantie 5, Turku).
The audience can participate in the defence by remote access: https://echo360.org.uk/section/cff5e677-e6d0-448d-8e2c-64527b8d95de/public
Opponent: Docent Joerg Lehmann (University of Newcastle, Australia)
Custos: Professor Petriina Paturi (University of Turku)
Doctoral Dissertation at UTUPub: https://urn.fi/URN:ISBN:978-952-02-0125-8
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Summary of the Doctoral Dissertation:
My doctoral research focuses on improving dose measurements in small photon fields used in modern radiation therapy. These fields, often less than three centimetres in diameter, are applied in treatments like stereotactic radiosurgery for small or hard-to-reach tumours. Traditional dosimetry methods are not reliable in such small fields, which creates a need for a new, more reliable techniques.
In the study, I introduced a novel measurement parameter called DAPR (dose-area product ratio) to characterize beam quality in small fields. I also evaluated a new small-volume ionization chamber designed for these quality measurements. The findings were verified through both experimental data and computer assisted Monte Carlo simulations.
A key discovery was that DAPR could potentially replace the commonly used TPR (tissue-phantom-ratio) metric, providing more reliable and less uncertain dose evaluations, especially in challenging clinical settings.
This research is aiming to contribute to more accurate and safer radiation treatments. Better dose determination means tumours can be treated effectively while minimizing harm to surrounding healthy tissue. This would improve both treatment outcomes and patient safety.
The audience can participate in the defence by remote access: https://echo360.org.uk/section/cff5e677-e6d0-448d-8e2c-64527b8d95de/public
Opponent: Docent Joerg Lehmann (University of Newcastle, Australia)
Custos: Professor Petriina Paturi (University of Turku)
Doctoral Dissertation at UTUPub: https://urn.fi/URN:ISBN:978-952-02-0125-8
***
Summary of the Doctoral Dissertation:
My doctoral research focuses on improving dose measurements in small photon fields used in modern radiation therapy. These fields, often less than three centimetres in diameter, are applied in treatments like stereotactic radiosurgery for small or hard-to-reach tumours. Traditional dosimetry methods are not reliable in such small fields, which creates a need for a new, more reliable techniques.
In the study, I introduced a novel measurement parameter called DAPR (dose-area product ratio) to characterize beam quality in small fields. I also evaluated a new small-volume ionization chamber designed for these quality measurements. The findings were verified through both experimental data and computer assisted Monte Carlo simulations.
A key discovery was that DAPR could potentially replace the commonly used TPR (tissue-phantom-ratio) metric, providing more reliable and less uncertain dose evaluations, especially in challenging clinical settings.
This research is aiming to contribute to more accurate and safer radiation treatments. Better dose determination means tumours can be treated effectively while minimizing harm to surrounding healthy tissue. This would improve both treatment outcomes and patient safety.
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